Generating DC electricity
on a boat.
    Galleon     Contact me.

This page updated: August 2014

Battery Charger (AC-to-DC)
Non-Engine (solar, wind, water) In General
Solar (photovoltaic)

Battery Charger (AC-to-DC)

SailNet - Tom Wood's "Standard Onboard Charging Systems"
BoatU.S.'s "12 Volt Electrical Systems"
SailNet - Tom Wood's "Creating a 12-Volt Spreadsheet"
Ron Romaine's "Offshore Electrical Systems"
West Marine articles

Battery charging stages:
  1. Bulk: charge at high current until about 75% charged.
  2. Acceptance: reduce current steadily and keep going until 100% charged.
  3. Float: maintain fully-charged battery.
  4. Equalization: overcharge at low current until voltage stops rising, to remove sulfation.

BoatU.S.'s "Battery Chargers"
West Marine's "Smart Battery Charging"
Article by Steve D'Antonio in 6/2002 issue of Cruising World magazine

Battery charger:
Paraphrased from "The Boatowners Mechanical and Electrical Manual" by Nigel Calder:
  • Want 3-step: constant-current, then constant-voltage, then float-voltage.
  • Must have current-limiter and thermal overload protection.
  • Want equalization capability.
  • Want ignition-protection so starter doesn't affect charger.

My experience:
I bought a Xantrex Statpower TrueCharge 40+ in 4/2002. Decided not to get remote panel; battery monitor supersedes it.

If I need 80A capacity later, I'll buy a second Xantrex and wire one to each bank.

The terminals on the charger accept 6 AWG or lighter; they do not accept 4 AWG.

For the very popular Xantrex products, price-shop around the internet. I found TrueCharge 40+ prices ranging from $500 at West Marine to $360 at D&B Marine.

[Within a year, my girlfriend had dumped me, and after she left I found I could live without running the generator. So the battery charger went unused from then on. I live on DC (from solar and wind power) and propane (for cooking).]

Some suppliers: Xantrex/Statpower, Guest, Charles Marine, ProTech, Sentry, Ample Power, Lamarsh, Newmar, Vanner, Mastervolt.

From Colin Foster on The Live-Aboard List:
Don't spend $130 on the Heart Echo Charge - it only puts out a maximum of 15 amps. The West Marine Combiner 50 costs less than half as much and puts out 50 amps.

From Gary Elder:
> I think it is best to keep my flooded house batteries
> (which are mostly deep-cycle, I think)
> fully charged as much as possible.

Yes, that is true, charged and watered is best. Very few 4D batteries are really deep-cycle - they are really truck/bus batteries that will withstand deep cycling.

> Keep a charger running constantly while attached to shore power. True ?

Maybe. An older style 'ferro-resonant' charger (you can tell by the hum) will 'cook' a battery if it is left charging too long, and will never fully charge the batteries. The newer 'smart' chargers will fully charge the batteries, then shift to a float mode (NOT the same as trickle charge) and after a couple of weeks check to see if the batteries need to be charged again, and re-start the charging cycle. I think you have the old style.

Because a boats electrical system can be damaged by shore power surges caused by lightning, I disconnect shore power when lightning approaches, and when I will be away from the boat.


SailNet - Tom Wood's "Standard Onboard Charging Systems"
SailNet - Don Casey's "Alternative Power"
BoatU.S.'s "12 Volt Electrical Systems"
SailNet - Tom Wood's "Creating a 12-Volt Spreadsheet"
Ron Romaine's "Offshore Electrical Systems"
West Marine articles

Alternator / voltage regulator characteristics,
mostly summarized from "The Charge Masters" article by Joe Minick in 10/1998 issue of Cruising World magazine:
  • Multi-stage versus constant-voltage.
  • Stage transitions determined by timer, or by current/voltage readings ?
  • Temperature-compensated ?
  • Positive (P) or negative (N) connection of regulator to alternator ?
  • Battery types supported.
  • System DC voltages supported.
  • Max field current supported.
  • User control or programmability for battery type, voltage ranges, etc.
  • Halogen bulb protection (lower charging voltage) mode ?
  • Monitoring / status reporting / alarms.
  • Monitor battery and alternator temperatures ?
  • Alternator current overload protection ?
  • Multiple battery-bank support ?
  • Multiple alternator support ?
  • Equalization (absorption) mode ?
  • User can reduce alternator load on engine if needed ?
  • Alternator load on engine minimized at engine startup ?
  • Alternator and battery current-sensing ?

Voltage regulator really is a "current regulator": regulates current running to batteries.

Alternator characteristics:
  • Output curves (current at various RPM) for various temperatures.
  • Mounting type:
    • Single or double foot (how many times does pivot bolt go through case) ?
    • 1-inch or 2-inch foot (length of pivot bolt sleeve through case) ?
  • Isolated ground (not through engine block) ?
  • Ignition-protected ?
  • Corrosion protection (noncorrosive brush holders, plated springs, impregnated windings) ?
  • Number of "poles" (frequency of signal to tachometer).

Alternator terminals:
  • GRD: ground (to engine block or battery negative). Might be through frame and mounting.
  • BAT: output (to battery positive; charging current). Usually biggest terminal.
  • FLD or DF or F: field (input from voltage regulator; controls output).
  • STA: stator (output to voltage regulator; ???).
  • AUX: auxiliary output (N-type only; output to voltage regulator; excitation circuit).
  • excitation wire (N-type only; input from voltage regulator; excitation circuit).
  • sense (if has internal voltage regulator; input from battery positive terminal).
  • output to tachometer.

Alternator output and expected life may be for 75 degrees ambient temperature; in Tropics, expect 50% of rated output, and spin it slower to avoid overheating ?

There are federal specifications KKK-A-1822A and KKK-A-1822B, Part 3.14.6, for ambulances which specify alternator characteristics. Nigel Calder says they include ability to operate continuously at full output in high temperatures, oversized bearings, heavy-duty brushes and heavy-duty diodes.

Alternator fan should suck air out of alternator, exhaust it at front.

From Giff on The Live-Aboard List:
Re: types of alternators:

Usually, P-type and N-type refer to the semiconductor junctions. For alternators, it defines the way the diodes are installed in the frame. Just about everything for the marine environment is a P-type.

An A- or B-circuit refers to the way that the field is controlled. A-circuit alternators are controlled by applying ground to the field whereas B-circuit alternators use battery to the field. I have only seen B circuit alternators on the boats I have owned. See Aerotech of Louisville -- Troubleshooting.

Voltage regulator suppliers:
Ample Power
Cruising Equipment
Hehr Power Systems
Lifeline Distributors
Revolution Technologies (Amptech)
Sea Air Land Technologies (SALT)

From Mike on The Live-Aboard List 5/2005:
I have installed several (including my own boat) Balmar ARS regulators. Out of all of the installations we have not had a single failure. The Balmar MC series regulators are another matter. The return rate on them is close to 40%. I think that they still have some bugs to work out.

From David at Salinas PR:
If you have an automotive alternator with attached regulator, you can take the regulator off and find a voltage adjustment screw on the side that was attached to the alternator. You can adjust that to make it put out higher voltage.

From David at Salinas PR:
You can charge [flooded?] batteries as hard as you like as long as their temperature stays low; feel the sides of the cases as they are charged.

Alternator suppliers:
Ample Power
Charles Marine
Hamilton Ferris

From Norm on The Live-Aboard List:
> They claimed what those things do is artificially make your alternator
> work harder to put a quicker charge into your batteries, but the flip
> side is that your alternator is working too hard and will ultimately
> have a shorter life expectancy.


The three-stage charger does indeed make your alternator work harder, this is the whole purpose of using it. (What "artificially" has to do with it I can't imagine - all machines are "artificial".) The ordinary automotive regulator works to fix the output of the alternator at one voltage no matter what the state of discharge of the battery. This is because the car battery is only discharged slightly so it need only be charged slightly while the alternator/regulator's real job is to power all the electrical devices in the car after the engine is running. The battery gets charged almost incidentally in the process.

This won't work for charging deep-cycle house batteries. House batteries are very deeply discharged compared to a car battery and need to be charged relatively heavily for a long time. The ordinary car setup will not do this because the regulator is set to too low a voltage. It would take "forever" to recharge a house battery this way and it would be likely that the battery will end up being chronically undercharged, the number one reason for premature failure of deep-cycle batteries.

I have a three-stage regulator controlling the alternator with the field current going through a large rheostat before it gets to the alternator. I have a center-off toggle switch to chose the rheostat only, off, or the three-stage with the output to the field going through the rheostat so I can choose manual or automatic charging. I use the rheostat to control the charge rate manually in the rheostat-only position, and to control the maximum alternator loading in the three-stage position. This keeps me from overloading the alternator by setting the maximum output with the rheostat.

An alternator should not be loaded to more than 70% of it's maximum output for the extended periods needed to charge a house battery. This is the point of truth in the advice from the fellows down at the garage. The rheostat insures that the alternator is not overloaded.

The absolute best is Gene Gruender's setup - a car type, internally regulated alternator to keep the starting battery up, AND a big honking externally three-stage regulated alternator to refill the house battery with a pair of solar panels and a wind generator to top off the batteries each day. This will insure the longest, most satisfactory service. And don't forget a pulser to knock off the sulphation.

From Gene Gruender on The Live-Aboard List:

Putting a 3-stage regulator on a car alternator will work, at least as long as the alternator can take the extra load. They really aren't designed to put out that much amperage for long periods of time. I know people who use them and have had good luck and will argue until the cows come home that they are just as good, but they weren't designed to take the extra use.

The high-output alternators have a couple advantages over the auto ones. First, they have better (maybe the right word is bigger) bearings, they are wound differently so that they can put out more amperage at lower speeds, and they have heavier wires and diodes. Of course, due to these things and the fact that they are built in far smaller quantities, they cost far more.


Personally, if I'm going to try to get large outputs for expended periods of time, I wouldn't try to do it with the stock alternator. Usually, they are 35 to 75 amp units, which aren't going to give you the results you want, even if they do hold up to the harsher usage.

As to belt and sheave size, my research and talking to Hamilton Ferris (the man who owns Hamilton Ferris company), I was told that you could run up to 150 amps on a 1/2 inch belt. That is what his published literature says, too. It will work, I've done it. I don't recommend it, though. It's at the limit. To do it, you need a very good belt. Make sure you really have a 1/2" pulley and the belt is in contact for the entire surface. Just because they call it a 1/2" pulley, doesn't mean it really is. I know. Try your local alternator rebuilder for this, it's about half what the marine guys want. (In my case, $18 vs. $40) Make sure the pulley sides go higher than the belt.

As to belts, there are many choices, just as you have many grades of oil and other things. Get the best. One is Gates Green Stripe. I can promise you that they will transfer more power than the standard auto belt, by far. I'm sure that other manufacturers make belts that are equal, but don't settle for the standard auto belt.

My system uses two 1/2" belts with a 150 amp alternator, exactly double what is required. My logic? It'll last a lot longer, and if I lose a belt I can deal with it when I choose, it's not an emergency.

Next thought: Belt ratio. What you want is a system that will put out the most amps at the lowest speed possible. To do this, find the max rated speed of the alternator (probably about 10,000 to 11,000 rpm) and the max rated speed of your motor. Find pulleys that will run the alternator at that max speed when your motor is turning the max speed. It doesn't matter at that max speed, but it will get your alternator turning as fast as possible at low speeds without over-revving it at top speed.

Does this make a difference? On my setup, I had a 7 1/2" pulley on the motor, and a 2" on the alternator. At the 800 rpm range I put out a few amps, maybe 10 or so, nothing to matter. I changed it to a 10" pulley on the motor, now I put in about 50 amps or more at an idle of 500 rpm, I put out full amperage (125 or so) at about 800 to 900 rpm. If you're living on the hook, that is a big difference. Now, if I'm idling my motor while raising the anchor, setting the hook or whatever, I'm making serious power. Before I was just burning fuel.

Comment: Lew is right, getting the alternator mounted is the hardest part of the whole project.

Comment: I don't think calculating engine horsepower required from amperage output is valid. First, they are two different animals, and there are lots of losses anyway, like belt friction, bearing friction, heat loss, etc. My research told me it took about 9 engine hp to make 150 amps [Don Casey says 1 hp to make 25 amps]. Your mileage may vary.

Comment: I'm not familiar with them, but I understand there are products that will allow you to use the maximum output of the alternator, or cut the output to a predetermined lower level. This is important if you're using something like a 10 hp motor to drive your boat, but also want to put a lot of power into your batteries. Use one setting while traveling, the other at anchor. Norm's rheostat setup may be a good way of doing this.

From Jim McCorison on The Live-Aboard List:
> I would think that some 3-stage [regulators] would have an adjustment
> for [running small alternator]. The Heart I got does not.

Some of the Balmar regulators do. They can be programmed for a maximum current draw and/or be installed with a switch which will significantly cut back on the charging current but not eliminate it. The idea is that if you are running a larger alternator on a small engine you can throw the switch when you want most of the power available for running the boat (e.g. bucking a current) regardless of the charging demands of the batteries.

From Lew on The Live-Aboard List:

The output capability of an alternator and the size of the battery bank are directly related.

The recharge rate of a [lead-acid ?] battery bank is about 15%, so if you want to recharge a battery bank at 150 A, you need a 1000 A [or AH ?] house bank to accept that rate.


From W G Nokes on SailNet's Gulfstar mailing list:
... Incidentally, I installed a separate field off/on switch, so I could turn off the entire alternator load when desirable. It has been handy a number of times.

From Jim Sovie on The Live-Aboard List:
Anyone looking for heavy-duty alternators should check the junkyards for wrecked police cars - nearly every one will be equipped with a good, well-built heavy-duty alternator.

From Arild Jensen on The Live-Aboard List:
There really are only about three makers of alternator core parts. These are used by dozens of aftermarket "assemblers" to create specialty house brand names. What distinguishes one "brand" from another in the specialty heavy-duty automotive/marine/truck market is how these basic parts are treated, finished and then assembled into a finished product. Not to mention how the marketing people rate the product in the hype.

Double-dipping in varnish is only a beginning. The better class of winding shops will use double-layered nypol insulated wire instead of enamelled wire. The grade of copper is also critical. You can get cheap magnet wire and you can get good magnet wire. However you cannot get good and cheap magnet wire.

You can use undersized bearings or oversized bearings. You can push a design to the max limit and get 100 amps out of it for a few hours; or you can use a conservative design having a larger frame, ample cooling flow, double fans, larger shafts and better heat sinks for the diodes, etc.

The latter will spin 24/7 and produce 100 amps for years. The other will barely last out the warranty period.

You pays your money and takes your chances. :-)

If you know what you are doing, and understand the spec game, then by all means scrounge in the scrap yards.


> What difference, if any, is there between automotive and marine alternators?

Lots of difference!! Here is the short version. :-)))

Windings are different in terms of wire size and number of turns. The marine HD version is often designed to work at a much lower RPM compared to automotive use.

Air flow, ventilation and fan design. Most automotive applications do not see the kind of long term heavy current output that you see in marine. A sailboat charging up a house bank might put out the maximum 100 - 150 amps for two or three hours in order to recharge a large house bank. By comparison, most automotive applications might see 100 amps for 10 minutes then a lower current tapering off to around 20 amps or less. Even when an over the road truck runs round the clock with team drivers the load on the alternator is around 40 amps for all lights. You end up with greater heat build up in a marine alternator. In addition, the anchored boat will attempt to charge a battery at fast idle not a full throttle. So the internal fans in the alternator will not move as much cooling air as the same alternator on a truck running at 80% full throttle.

Bearings. Many automotive alternators have sleeve type bearings instead of ball bearings. Sometimes only the front is ball bearing; the rear is still sleeve type.

Finish. Automotive types are usually raw aluminum castings and barely coated (varnish) iron laminates. Oxidized aluminum is called aluminum oxide. What do you see on a lot of commercial sand paper? (right - aluminum oxide) So when you have raw aluminum, you get oxidization and this powder will get into the windngs due to normal vibration. When you have this hard grit sitting in between the wires in the windings the continual motion will chafe and rub the alumnimum oxide particles against the insulation until it fails.

Regulators. Normal automotive alternators have a single-stage regulator set for somewhere about 14.2V - 13.9 V. A good marine alternator should have a three-stage smart regulator to maximize house battery charging and minimize engine run time. Not all automotive alterantors lend themselves to easy conversion from internal to external regulation.

Brushes. An automotive alternator is not rated ignition-proof. Most marine alternators are. Your insurance broker may have an interest in whether or not yo have ignition-proof equipment installed in or near your engine.

Ignition-proof brush holders just happen to be much better at also keeping out dirt and moisture, so they last longer.

From Arild Jensen on The Live-Aboard List:
A couple of things to consider when doing an [alternator] adaption from automotive use.

On smaller engines, especially with BIG alternators you should avoid having a single common belt driving both the alternator and the water pump.

To keep such a big alternator from slipping you need a very tight belt. However, this places an excessive side load on the water pump bearing and it will fail prematurely.

Secondly, make sure the automotive alternator has a ball bearing at the back as well as the front. Some automotive types have a sleeve bearing at the back and will not stand up to prolonged loading at the full amperage output. The sleeve bearing will overheat and or wear out prematurely.

Most automotive charging is normally done at less than maximum output whereas marine charging, especially with a modified or 3-stage regulator, is done at full output. This creates much more heat inside the alternator and you must provide air flow to dissipate it. Some of the marine adaptations simply involves a better fan and/or additional cooling slots in the casing. As a simple precaution buy a cheap automotive indoor/outdoor thermometer and attach the remote (outdoor) sensor to the alternator case. Now you can check to make sure it doesn't over heat.

Lastly, be cautious about forcing the alternator to produce maximum amps at too low a rotor speed (also = fan speed) since this will definitely cause over heating of the windings and burn it out sooner or later. I once saw four 200 amp units burned out in as many weeks due to this oversight. The owner wanted full 200 amps output at idle. Yeah sure!!

From article by Don Casey in 12/2001 issue of Blue Water Sailing magazine:
  • When sizing alternator, use hot rating, which typically is 25% less than cold rating.

  • Need separate belt(s) for big alternator. 3/8-inch belt with 2.5-inch pulley can drive about 75-amp alternator. Going to 1/2-inch belt increases to maybe 100 amps. But watch for increased side loading on water pump.

  • Stacking pulleys on the crankshaft increases leverage on it (increases side loading).

  • Need very strong mounting for big alternator, especially if engine has few cylinders (more pulsing). Brackets should be mild steel.

  • If high-output alternator, regulator should have a start-delay feature.

From presentation by Ron Romaine of Farallon Electronics:
Alternator pivot bolt should be grade 8, not stainless steel (too brittle).

My experience adding a new alternator to my engine, 4/2002:
I started out wanting to keep my old alternator (50-amp Motorola automotive) mounted, and add a new mount for a big (150+ amp) large-frame double-foot alternator. My engine is a Perkins 6.354 (120 HP), so engine load was not an issue.

It turned out I had to design a custom bracket myself, from scratch. I couldn't even find a standard alternator bracket that I could use as a base, and add to. I did a small cardboard mockup, then a full-scale cardboard mockup, complete with bolts. This was invaluable; I caught a lot of mistakes, could see how much space it would take up, took it to a metal fabricator to get a cost estimate ($250).

But finally I decided it would take up too much space on the engine, and be hard to mount strongly enough.

Worse, I completely failed to find a dual-1/2-inch-belt 11-inch pulley that I would need to mount on the front of the crankshaft. Mounting it would be no problem, but no one sells a solid 11-inch pulley. It would have to be fabricated from scratch. Only one shop in town might be able do it, and he was on vacation. Might have cost $200+.

Since I was going to add the new pulley on top of the existing one, it would have a moderately long "lever arm" on the crankshaft (bad). It would partly oppose the existing belt (good).

So I took the easy way out and bought a drop-in replacement for my existing alternator. But I bought it from a local shop that makes custom alternators, with a custom "smart" internal regulator. Cost $270.

Good: it is fairly high capacity (supposedly 100 amps, although I never see more than 45 or so); puts out plenty of juice even at low RPMs; the regulator is "smart" (3-stage); internal regulator cheaper than external regulator (saved $350); small-frame $120 cheaper than large-frame from same guys; installing it was easy.

Bad: the guys who made it have only a guess at the capacity (they certainly don't have performance curves); the regulator lacks most features including temperature-sensing and startup delay; uses old single-1/2-belt system so there is slippage if batteries are low and I go to cruising RPM; my tachometer is screwed up (not sure how to fix this); not ignition-protected. [And the regulator went crazy a year later and I had to send the whole thing back to get swapped for a new one.]

I'm thinking of changing to dual-1/2-belts. The crankshaft pulley is dual already; would have to get new pulleys for water pump and alternator. The water pump pulley alone will cost about $350 !

Alternator-independent tachometer alternatives: magnetic pickup (senses flywheel teeth as they go by), shaft-drive, maybe photo-electric ? Some sources:
From Bob Johnson on The Live-Aboard List:
Balmar has the same [tachometer-affecting] problem; it's related to the increased number of poles. I tried finding a tach to replace the one on my Volvo 2002 without any luck.
From Brian Timmins on the SailNet liveaboard-list:
... Teleflex has senders and drive tangs that work with square drivers and round-keyed drivers. ...
From Bob on The Live-Aboard List:
I put a Balmar 100 amp alternator on my Volvo 2002. When I asked about the RPM issue they told me they had no cure other than to "find someone" who makes a different pickup. My understanding is that typical alternators are 12-pole and the Balmar is 18.

To recalibrate tachometer, get reference tachometer from auto-parts store, or handheld tachometer from model airplane store.

Belt should stick up above rim of pulley; if it doesn't, need new belt.

From "The Lightbulb Regulator" article by Helmut Bender in 6/2002 issue of Cruising World magazine:
How to make an emergency manual regulator:

Need access to Field terminal of alternator. May require serious surgery on alternator with internal regulator (no Field terminal): need to get to the brushes and connect one to ground and the other is your Field terminal.

Need several lightbulbs totalling 50 to 60 watts, and a switch for each.

Wire the bulbs in parallel, with a switch controlling each. So you end up with a load that you can vary from 0 to 60 watts or so. This will act as regulator.

With engine and ignition and battery switch off, measure resistance between Field terminal and ground. If very low, you have p-type alternator; if high, you have n-type. If p-type, use battery positive terminal in next step, else use negative terminal.

Connect the variable load (manual regulator) between the battery terminal (positive or negative depending on alternator type), and the alternator's Field terminal. Disconnect bad regulator.

Turn all manual regulator switches off, start engine, then turn one switch on and observe alternator output. Turn remaining switches on, one at a time. Now should have full current output of alternator.

As batteries charge, voltage will increase slowly. When it reaches 14.2 to 14.4, turn off one switch. Voltage will drop, then slowly climb again. Repeat until all switches are off.
From Nick Wigen on Cruising World message board:
Using a "smart" regulator is a good idea. I put one on our old boat and was very happy. Haven't gotten around to it yet on our newer one.

Keeping your alternator happy depends on proper cooling. Cooling is a function of engine room temerature and MORE IMPORTANTLY airflow through the alternator.

When charging batteries at the maximum alternator output (using the smart regulator) keep the engine revved up. Ours would put out the full 100 amps at only 800 engine rpms. Put out the same at 2400 rpm. Air flow through a fan cooled system like an alternator is effected by the ratio of RPM's squared. Going from 800 to 2400 increases that airflow by a factor of 9. Also, the mechanical power put into the alternator is speed x torque so running 3 times faster reduces the pull on the drive belt to a factor of 1/3.

I work with industrial variable speed motors and generators all the time. They are typically 100+ kilowatt units but we are always careful to derate the output at lower speeds because of the cooling issue. The larger units have temperature sensors built into the stator coils and it's amazing how quickly things get hot if we pull too much torque at low motor speed.

By the way, I also like using automotive alternators figuring I can buy 3 or 4 for the cost of a single Balmar. We always carry a new spare but by not running it underspeed and overheating it we've never had to use it in 8 years (used only on weekends and summer cruises). We normally run our engine at 1800 rpm for battery charging not under way, not the 2400 mentioned above. Seems to work OK.


One thing I did was install a larger drive sheave on the engine. If you look at an automotive installation you'll see a 2.5 or 3.0 to 1.0 ratio. That means that the alternator will spin at over 12,000 rpm on a regular basis. I wouldn't want to run one that fast continuously but it shows that there are no mechanical impediments to running one fast. I set ours up with 2.5 to 1.0 so at our normal cruise of 2400 rpm it ran at 6000 rpm. Used an Ample Power 3-step regulator. Kept a close watch on belt tension and replaced it about every 2 years even though it looked OK. Worn belts don't grip very well.


I met a guy on the dock one day who was complaining that he'd burned out 3 Balmars in 4 years of weekend and vacation use. We chatted a while and it came out that he bragged he could get full output running his engine at 700 rpm idle. Thought he was being nice to his engine. I think the problem was not the quality of his alternator but he was running it at too low speed.

... more alternators are destroyed running too slow than too fast ...

From Laurie on Cruising World message board:
... the problem with cheap alternators: they burn up under the demands of a modern regulator !

Automotive alternators are designed for 'top-off' duty. Marine-duty alternators are designed to pump hundreds of amps per hour into your batteries. The automotives just can't stand up, they were never designed for that duty. The coil wiring is much smaller to save weight. That's why they heat up -- more resistance ...

You need a modern alternator to match the demands of a modern regulator. Ample Power has a lot of reading and experience on their website.

They almost never sell their high performance regulators without matching an alternator for it. Reason: they were burning-out alternators left and right -- and people were blaming the regulators. It was really the sign of a fantastic product.

From Bryan Genez on World-Cruising mailing list:
I've had Balmar external regulators on my boat for years. A few have failed and had to be replaced. In my experience, the more complex the unit, the more likely it was to fail. When working - which is most of the time - they do the job very well. But I'd recommend you get an inexpensive automobile or truck regulator and keep it as a spare. A $10 truck regulator saved my bacon when I had a failure early in a four-month cruise. At the time of the failure, Balmar was shut down for the entire month of August, so that their employees could go on vacation. There was no one at the company to provide service or even answer the phone. Don't know if that's still the case.

Generator versus Alternator (or, Why does everyone use alternators ?):
  • Produces DC.
  • Requires higher engine speed than alternator.
  • Contains brushes (less reliable).
  • Produces AC (has rectifier diodes to give DC).
  • Running with no load will burn out rectifier diodes immediately.
  • Smaller and lighter than generator.
  • More efficient than generator.
  • No brushes (easier to maintain, sparks less) except for field current.

Non-Engine (solar, wind, water) In General

There seems to be a major choice to make:
Using solar/wind/water is attractive because it is clean, quieter, cheaper, can run unattended, and doesn't consume fuel. But a diesel engine likes to be run hard and often; if you don't run it for a while, corrosion starts, stuff grows in the fuel, etc. And alternative sources are less reliable and clutter up the deck.

SailNet - Tom Wood's "Alternative Battery-Charging Systems"
"Renewable Power Systems" article by Kevin Jeffrey in Nov/Dec 2001 issue of Blue Water Sailing magazine

Summarized from "Renewable Power Systems" article by Kevin Jeffrey in Nov/Dec 2001 issue of Blue Water Sailing magazine:
Typical efficiency ratios (input energy to amps in battery):
  • Solar: up to 16% (but the input is free).
  • Wind: up to 30% (but the input is free).
  • Water-powered: roughly 20% (but the input is mostly free).
  • Engine-driven alternator: roughly 10%.
  • DC dieselcharger: roughly 20%.
  • Genset and battery charger: roughly 20%.

From James Forsyth on the SailNet liveaboard-list:
In reasonably sunny climates, you can figure solar panels will produce AH roughly equal to 1/3 their rated watts without messing with them. E.g. a 45 watt panel should be expected to produce about 15 AH per day. You can increase that to about half if you fuss with them to keep them properly oriented, so you might get 22 or 23 AH from a 45 watt panel - but that's under ideal conditions. That's a useful amount of electricity, but not enough to run a boat, even with two or three panels.

Wind generators vary widely in both output and noise. The small ones, such as Ampair 100's and the Fourwinds three, are virtually silent, but their output is pretty small too. We looked at a lot of different models, read a lot of reviews, and finally settled on a Fourwinds Two. The output still varies with windspeed, but it comes pretty close to the advertised values. It's quiet, but not silent. Most of the time underway the wind generator is quieter than the usual wind and water noise. In winds of under 20 knots, we actually have to look at it to be sure it's running. You can hear it at anchor, but we don't find it obnoxious. My suggestion is to find people in your area who have different brands, then go stand by their boats, or dinghy next to them, and listen. Also, put your hand on their hull or toe rail to check for vibration. We're quite satisfied with ours. If you're considering a Marine Aire, talk to people on boats near one ...

With the wind generator and one solar panel we can supply most to all of our needs if it's sunny, and if the relative wind stays at 10 knots or more, and we're careful. We have a house bank of about 400 AH, and a 100 amp Powerline alternator with a Balmar 612 regulator run from our main engine. We keep our boat on a mooring in the Chesapeake, and find we never have to run the engine solely to charge the batteries.

We also have a conversion kit to use the generator portion of the Four Winds as a water-powered generator when we're offshore. The wind generator doesn't work all that well going downwind, when relative wind is light. Used as a water-powered generator, it provides massive amounts of power. I believe the Ampair has a similar set up, and it too should provide lots of power offshore.

From Bob Stewart on The Live-Aboard List:
I have a windbugger wind generator. I consider fairly quiet. I've found the problem with wind generators is the lack of adequate wind. It's amazing how rare a steady wind above 15 knots is even in the Eastern Caribbean. If I was going to start over and put an alternate energy source aboard I'd take the money I used on the windbugger and get two large solar panels (100-120 watts). I've found most anchorages have far more steady sun than steady wind.

Various stores:
Northern Arizona Wind and Sun (good prices)
Solar Electric
Rocky Grove Sun Company

No sales tax on solar panels, nationwide.

Summarized from article by Richard de Grasse in Mar/Apr 2008 issue of Ocean Navigator magazine:
  • It's important to have the solar panel adjustable to the angle of the sun.

  • Our Air-X Marine 400W wind generator does the job and is reliable but needs at least 13 knots of wind to generate a meaningful amount of electric current. ... the wind is up and down and blows less than 13 knots most of the time. ... the harder the wind blows the noisier it gets: when the wind blows 20-25 knots while we're trying to sleep at night we frequently shut down the wind generator. ... a steady 15 knots of wind over a 24-hour period happens only a couple of weeks during a six-month winter cruise. ... It's clear our wind generator is much less cost-effective than our solar panel and our Honda 2000 generator. ... advancements in wind generation technology usable on cruising boats haven't kept pace with advancements in photovoltaic panels or compact gasoline generators.

  • Wind generator affects sailing performance unless shut down, creates noticeable wind resistance, is a hazard in 20+ knot winds.

  • We plan to double solar-panel size and remove the wind generator.

From David Cantor on World-Cruising mailing list:
Generally, charge regulators for solar and wind are entirely different beasts. Solar panels can safely be open-circuited, and that is how their associated charge controllers work. They basically open up a switch when the desired voltage is reached.

This would destroy most wind generators. For wind, if the circuit is open-circuited, the voltages in the windings go sky high and they blow up. So charge controllers for wind use some kind of diversion load (water heater element, big resistors), and dump the excess power there (as heat).

Usually, having two charge controllers causes no problems, though there could be some slight inefficiency if both sources are putting out lots of juice.

Blue Sky Energy was experimenting with a dual solar/wind controller, I don't know if that ever made it to market.

Solar (photovoltaic)

Summarized from "Renewable Power Systems" article by Kevin Jeffrey in Nov/Dec 2001 issue of Blue Water Sailing magazine:
Types of solar panels:
  • Rigid ("standard"): rigid frame and glass cover.
    Best cost-per-watt ratio; tough but don't walk on them.

  • Semi-flexible: no frame and a polymer cover.
    Higher cost and less life; can be walked on.

  • Fully flexible:
    Even higher cost-per-watt; half as efficient as standard panels; handle shading well; can be walked on.

Major brands / product lines:
  • Siemens / Shell.
  • Kyocera.
  • BP Solar / Solarex.
  • Sharp.
  • Unisolar.
  • SunWize.
  • ICP (West Marine).
  • AstroPower.

Bob Pone's "Solar Panels"
SailNet - Don Casey's "A Little Help from the Sun"
Don Casey's "Installing a Solar Panel to Maintain Batteries"
SailNet - Don Casey's "Alternative Power"
SailNet - Sue and Larry's "Choosing and Installing Solar Panels"
SailNet - Kevin Jeffrey's "Charging with Solar Power"
West Marine articles
Solar Panels - Price Survey

"One of the most expensive ways to generate electricity." [But looking better as fuel prices soar.]

I think solar is the best way to charge batteries: it is gradual charging, tends to keep batteries close to fully charged all day, works unattended, has no moving parts, makes no noise, produces the most output when you need it the most (hot, still days when the refrigerator is working hardest).

Output voltage is directly related to the number of cells (want at least 36).

Where to mount solar panels: on top of bimini/dodger, off stern pulpit ?
Could use folding solar panels, so they don't take up a lot of space while under way.

Solar panels need some airspace (1/2") for ventilation underneath.

Paraphrased from "This Old Boat" by Don Casey:
If solar-panel output is < 0.5% of battery capacity, it can be directly connected to the battery with no regulation.

"Siemens or Kyocera deliver better than Unisolar"

AIM in Marathon says Kyocera delivers power from sun-up to sun-down; Siemens won't. Now that I have Kyocera panels, I think they're right about Kyocera.

From S. Airing on Cruising World message board:
I have had two USF-32 panels on the Chesapeake Bay for 3 seasons and they have never really reached their rated output even in June and July. My one Siemens SP-65 panel easily produces more power.

From Gary Elder:
... A VERY optimistic assumption is that you MIGHT do as well as 50% of the rated output on a GOOD day. From there it's all downhill, sun angle, shadows, thin clouds, and lead length / wire size all make it worse. ... The last time I played with a top-quality solar panel, I was able to get close to 50% output, measured right at the output junction box, for about 9 hours per day, if I worked at keeping the panel oriented to the sun.

I have yet to meet a cruiser who was happy with his solar set-up, if he was trying to avoid repairing a gen-set. All it takes is a couple of cloudy days to have a refer full of spoiled food and an engine that won't start, or even a bilge pump that won't run. Ouch.

I have met a few people who, at first, claimed to be happy with their set-up, but after talking for a while it usually came out that they had no refrigeration, no bilge pumps, and used candles for light ...

Solar panels are great for those who leave their 12V system alone for several days or weeks at a time, but for daily use they are not so hot.

From Brian Woloshin on Cruising World message board:
I had a Four Winds wind generator and switched to solar. Even in the windy Caribbean, solar produced more power and it is silent! My six Siemens SM-55 panels can produce over 100 amp-hours a day in the tropics. When you are at anchor you will want a calm anchorage which is in conflict with getting power from a wind generator. If you are doing downwind ocean passages you will have considerably less output and would be better off with water-driven. Solar output is also reduced considerably when sailing due to shading, an alternative like water-driven is needed.

From Garbonzo on Cruising World message board:
... The size and type of panel is important, but not as important as location.

I have 3 panels, older Arco 80w units I bought on EBAY, and have found that they need to have as much uninterrupted access to the sun as possible.

The most efficient units, the monocrystalline units, such as by Siemens HAVE to be in unshaded sun to work. Covering up just 1 cell in an array will drop the output to almost nothing. If you locate them under a boom you might as well not have them, except for trickle purposes. The polycrystalline and amorphous units are less sensitive to partial blockages.

From Brian Woloshin on Cruising World message board:
Selecting solar panel type/size has more to do with how you plan to mount it than the power rating - to a point.

Solar panels come in two basic forms: rigid and flexible. After that there are the dimensions, shading impact and cost/power ratios.

I am not a fan of flexible panels because:
1) The cost per watt is higher than rigid.
2) The power produced per square foot of panel is less. and
3) the expected lifetime of the panel is significantly less.
The plus side of flexible is that they are lightweight and easy to install.

Rigid panels are more efficient in both dollars and power per sq. foot. But they require a lot more effort to mount properly and cannot take rough treatment - they are, after all, covered in glass.

All solar panels suffer from shading effects. A partially shaded panel produces much less power that one fully exposed. This effect is far more significant than the percentage of the panel shaded. A non-producing cell is also less conductive so power is lost from the more active cells. There are newer panels that have bypass diodes for each cell that reduces this effect and if I were shopping for panels today I would look into these. Having more panels is of benefit here because shading of one panel does not affect the output of others. Most panels have blocking diodes for the whole panel (at least Siemens does).

The next issue is how and where are you going to mount them. I chose the panels I have largely because they fit over my bimini well. When you choose to mount them consider three things:
1) Out of the way of sources of shade.
2) Out of harm's way. and
3) Do you want to be able to adjust the angle for best efficiency?
On point three I chose to add extra panels rather than concern myself with constant adjustments. Wherever you mount them, mount them securely.

Wiring should be heavy. Depending on total current produced, you don't want to lose hard-earned power warming up your wire. There are tables in various catalogs on wire size selection. A circuit breaker should be placed close to the battery bank to protect it in case of a short in the wiring. For the circuit breaker wiring consider the panels as the load.

As for charge regulators I cannot really recommend a product. When I had four SM-55s my holding plate refrigeration running twice a day was all the regulation I needed. When I added two more panels I also added an NC-25 regulator but was unhappy with it and returned it. The problem was that at high sun angles my panels put out 21 amps. This raised the battery voltage to where the regulator would disconnect the panels. Without the panels the battery instantly dropped below the threshold and the regulator turned back on. Since this regulator uses a relay it actually buzzed like an alarm and scorched the contacts. A good regulator should sample voltage over a time interval and then decide to turn on or off. I have not decided on a new one to try.

Other important considerations: So-called "self-regulating" panels are worthless. They do this by producing a lower voltage and thus taper off output as battery voltage rises. There must be a voltage difference for current to flow. The panels must produce a voltage higher than the batteries voltage to work. Also, if you mix panel sizes it is best to not mix number of cells in series (voltage ratings). The lower voltage panels won't produce to their power rating.

My installation is six Siemens SM-55s, mounted above the bimini on a Nordic 44. Backstay shading does not seem to affect it and the boom does not extend that far back. When under sail the shading from the main has a considerable effect on output. I used 12 gauge wire to a 25 amp circuit breaker into 500 AH of golf cart batteries. My biggest load is holding plate refrigeraion which I activate by timer twice a day. It runs about 45 minutes each time and draws 40 amps when running. I sail with an old Autohelm 6000 autopilot that also burns a lot of power, especially in tradewind sailing. I also have an ammeter in the solar panel circuit and an Amp-hour + 2 [predecessor of Link 20] to monitor battery state.


You MUST have a charge controller with gel cells and it MUST be set right. Gels are not as forgiving as wet cells when it comes to overcharging.

... In the tropics I got about six times peak amperage in amp-hours (i.e. for six SM-55s about 120 AH/day). That is with fixed mount on bimini, no adjusting for sun angle. ...

From Jerald King on Cruising World message board:
I've studied solar for several years now. My experience based on quite a few installations is that your daily long term average power output, measured in amp hours, will be about 1/2 the rated wattage. That means a 55 watt panel will put out about 20 - 25 amp hours per day.

This assumes heavy wiring and very clean connections, and few if any shadows.

I used #4 wire from the solar panel junction box on the arch down to the controller. That was a run of about 18 feet. The voltage drop using #4 wire was about 0.2V, the calculated voltage drop for lighter wire over the same distance was #8 0.58V, #10 0.92V, #12 1.46V.

Another way I use to determine power output is to take the calculated power (amperage = watts/voltage) and multiply it by 0.7. The 0.7 takes into account shadows, voltage drops, dirt on the panel, etc. Then you can use a solar hour chart (solar insolation) from the Dept of Energy to determine how many hours per day you can expect to get good sunlight.

For example, at Richmond VA you can expect 4.5 hours per day during the summer and 3.44 hours per day during the winter.

It is my experience that it is easy to overestimate the amount of solar generated power you will be able to put into your batteries.

From Rick Morel on The Live-Aboard List:
The way to test a panel is to "short it out" with an ammeter in full sunlight. The current should be the rated max. It was very, very difficult to bring myself to do this!

Someone told me that solar panels can "wear out" after 15 years or so. But I asked Don Casey, and got this:
Good panels are typically warranted to lose less than 10% capacity in 10 years, but that suggests something just under a 1% decline per year might be expected. They work by electrons being displaced by radiation and even though most of the electrons find their way home with a completed circuit, it makes sense that some are lost. So they do wear out, in a sense, but most failed panels I have seen failed for other reasons, typically failed internal connections, water intrusion, or some other damage, not from loss of capacity. I always advise checking high-noon output on new panels to get a baseline, but have never taken my own advice. But you could check yours now for a few days to get an average, then check them again in a year to see if they show measurable decline.

Charge Controllers:
Desired features:
  • Solid-state (no relays).
  • Voltage adjustment.
  • 3-stage charging.
  • Automatic periodic equalization, or at least a manual equalize capability.
  • Supports battery type you have.
  • Charging capabilities: apparently relay-type is low-end/obsolete; PWM is okay; MPPT is better; MPPT with "boost-and-buck" is best ?
    Apparently the difference is: most controllers keep current unchanged and cut the 18V or so coming from the solar panels down to 14V or so to the batteries, with current unchanged. So output power is 14/18 of input power. But "boost-and-buck" boosts current to compensate for the voltage loss, to keep output power equal to input power.

Some product lines:
  • Trace (Xantrex).
    Lots of people very happy with these.
  • FlexCharge (West Marine).
    One knob for voltage control.
  • Lyncom.
    Some solar companies have dropped them, citing problems.
  • Morningstar ProStar.
    Special coating that helps protect them in the marine environment.
    But no voltage adjustment.
  • Solar Boost.
  • Ample Power Smart Charge Manager.
  • Coleman Air C40 controller.
  • Eco-Worthy MPPT-12/24-20A.

  • I talked to several people who have Trace controllers, and they are very happy with them.

  • Someone told me: German-made controllers don't have common ground connection. Don't know which ones are German-made.

  • Shunt-type versus series-type ??? Maybe series-type brings the charging wires right through the controller, and shunt-type uses a separate shunt and sense wires to the controller ?

  • My understanding is that controllers for solar and wind differ in this way: when too much / unneeded output from solar, just disconnect / open circuit; when too much / unneeded output from wind, must dump current into a dummy load.

  • A friend tells me that Eco-Worthy MPPT-12/24-20A is more advanced than the others, can convert panel's low current at high voltage into higher current at lower voltage to batteries.

  • Apparently new panels such as Kyocera 245 produce up to 30 volts, and you use a special controller that reduces voltage to the normal 13-16 charging range, while increasing the current. One downside of this: if the controller fails, you can't jury-rig by just connecting your panels directly to your batteries.

From Frank / Tip:
Had a Flexcharge NC25 installed on my two Siemens / Shell 85-watt panels and yesterday it smoked. All positive lines had 15 amp fuses and the voltage sensing line had a 2 amp fuse. Yet something caused it to burn and smoke filled the boat cabin. ... What triggered it seems to be related to a shore power event because when I turned on shore power within two minutes we had smoke in the cabin. I've traced all wiring and everything is correct. The only thing I can guess is that when the Trace Inverter/Charger kicked on a spike may have hit the Flexcharge. My Trace unit has been a great performer and I have been through this process of powering up and down from shore power before, so I don't know what changed. Also the Flexcharge is supposed to be able to handle any spikes of up to 1500VA and 140V continuous without damage. ...


I called the folks at Flexcharge and was very pleased with the responsiveness and outcome. The summary is this: my unit was an older design and they have heard of this before if a large volt / current spike hits the system (which seems to be my case) or if the system has experienced many such spikes over time. The reason it only smoked and didn't catch fire was because the materials are fireproof. This was my experience – it smoked but never flamed. The new units are much more robust and they have replaced mine at no charge.

  • Blocking: between panel and battery, to prevent panel from draining battery at night.

  • Bypass: if two or more panels are in series, a bypass diode across each panel prevents reverse voltage across that panel if it gets shaded. Current from the active panel will go through the bypass diode of the shaded panel, instead of through the shaded panel itself.

  • Isolation: between any charging source and each of several batteries, to charge the batteries together but have them drive separate loads.

[ask about factory-second panels]
Northern Arizona Wind and Sun (good prices)
SunWize Technologies
Solar Electric
Rocky Grove Sun Company
EcoVantage Energy Inc
Effective Solar Products
Solar panels at Hotwire
Sun Electronics

My experience:
I bought two Kyocera KC120 panels and a Morningstar ProStar PS-30 controller in 11/2002.

I chose Kyocera because: several people recommended it (especially for partially-shaded or low-light situations), it gives more energy/$ than Siemens, and it gives slightly more amps and slightly less voltage than others (I think 16.9 volts is high enough; I'd rather have the extra amps).

Decided not to get digital display on controller; battery monitor supersedes it, mostly.

The terminals on the Morningstar and Trace controllers accept 6 AWG or lighter; for 3% loss on a 40-foot run of 30 amps (if I get 2 more panels in future), I wanted to use 4 AWG. Ended up using 6 AWG wire: figured the voltage drop would be highest at highest current, which is the "bulk" stage of charging, when voltage is lowest anyway.

Price-shop around the internet: there was a large price range for the solar panels.

Be very careful when removing the solar panels from the box; they're big and heavy and awkward, and I nicked the back of one of mine with the corner of the other. A deep gash in the soft back would ruin a panel.

Make the solar panels removable by having bolted-together terminals (lugs) in the wiring. More secure than connectors.

Wiring is a non-trivial cost: I spent $115 on cable and lugs. I used 6 AWG to the engine compartment and 8 AWG between panels.

Make the solar panels tiltable in any direction by putting two or three hinges with removable pins on each edge. To tilt to one side, remove pins from all hinges except the hinges on that side. To hold up in tilted position, make two sticks with hinge-halves on the ends; pin the sticks in place. Wanted stainless-steel hinges with removable pins; couldn't find any in appropriate size, or for reasonable price. Ended up using cheap zinc-plated hinges and grinding the end off each pin to make them removable.

I painted the cables to protect them from UV. I used polyurethane topside paint; someone suggested using refrigerator paint instead. Or a conduit.

Running the cables without drilling new holes was tough. I snaked them through a corner used by instrument panel wiring into the engine compartment, but they filled the hole completely; it was hard to get them through.

After 3.5 years of use:
They work great; I love them ! The controller does charge my golf-cart batteries so high that they get low on water; I have to keep topping them up. Other than that, no complaints. They keep up with my daily usage (mostly, refrigerator and laptop), even left lying flat (not tilted toward the sun). I shouldn't have bothered to make them tiltable. [But now I'm thinking of adding a wind-generator to get some power at night. I can't use my laptop in the late afternoon or night, or my batteries will get too low.]

After 5 years of use:
One of the panels has died: shows proper voltage (19V) open-circuit, but under any load it drops to 8V and puts out no current. A dealer tells me this is a rare but known failure mode.
Kyocera warranty person wrote: "You are not required to return the modules to us until after you receive your replacements. This way you have appropriate packaging for the return shipment. And yes, Kyocera does pay for shipping (both directions)." Excellent service from Kyocera !
They want to replace both panels, which is a good idea: the second panel may not be putting out full rated power.
[And I'm about to add a wind-generator to the system; should have done that sooner.]

After 5 years of use:
I added a KISS wind-generator to the system. At times, it puts out more than 15.3 VDC. When it does this, the PS-30 solar controller flags the battery voltage as a fault condition and goes into "high voltage disconnect" mode, where it refuses to charge batteries from the solar panels !

After 7-8 years of use:
I added a bypass switch to the solar controller, to let the panels charge the batteries directly sometimes. This provides equalization, and also avoids the wind-gen-high-voltage-disconnect problem. But it overcharges the batteries.

After 9 years of use:
When I bought a new VHF radio, I found the Morningstar PS-30 solar controller was causing a hiss in audio of both of my VHF radios. Got this from Morningstar tech support:
The noise is caused by the 300Hz PWM regulation of the controller. It should be present only when the controller is in regulation (flashing green LED).

To get rid of this noise, you can try to filter it by:
  • Using chokes or filter capacitors, or
  • Reducing the length of wire runs, or
  • Twisting +/- pairs together.

Or you can put the controller in On/Off 'low noise' mode. To do this, you will need to take the plastic case off the unit (4 screws on the back hold it on). In the upper right corner of the circuit board, there is a large ceramic resistor that stands off the board and is labeled 'J11'. Snip one of the leads connecting the resistor to the circuit board and this will put the controller into low noise mode.

This should be done only after you try filtering the noise first. Low noise mode is less efficient for charging than the standard PWM mode.
Sizing the filter capacitor across the output cables, from Ken on "Silverheels 3":
Pick a resistance you want to impose on the AC, say 5 ohms.
R = 1 / 2 pi F C
C = 1 / 2 pi F R
R = 5
F = 300
C = .00010616 = 106 microF
Maybe use a big electrolytic capacitor.

Bought a 100 uF capacitor, put it across output of solar controller, didn't help.

After 9.5 years of use:
I suspect the Morningstar controller doesn't charge my batteries hard enough, never getting system voltage much over 14.0 VDC. I've started bypassing it a lot more, connecting solar panels straight to batteries, getting up to 14.5 VDC or more.

Troubleshooting solar charging problems, from Steve Williams:
Measure the output of the solar controller, to see if it is at the same voltage as the battery. If different voltage then a loose/bad connection somewhere.

You could bypass the solar controller (but be sure that you disconnect the controller solar side, as some controllers short out the solar cell as the way to control the output of the controller, so if you jumper the controller input with the output you could damage it).

For troubleshooting you can take the solar controller out of the circuit. until the battery gets close to being fully charged; the voltage will be below 14.2V.

Clean all the battery terminal connections. I would also do a Pull test on all the crimps on the wires and one may come apart.

From Lee Haefele on The Live-Aboard List 12/2006:
Evergreen Solar Panels, Warning:

I purchased 5 Evergreen 120 solar panels in Sept. 3 of 5 have gone bad, the diodes are shorting out. No need to comment on theory, I have long electronic experience, these are defective, one was DOA.


These are US-made, Evergreen denies knowledge of any problem, says diodes can only be blown by connecting backwards to power. Says they have only had problems on small home installed systems. My local dealer (I bought these at a real store in Ithaca, NY) is MIA and does not return my calls. I have spent my whole life working in electronics, I know which is the + and - wire, I test them and apply labels. This is making me grumpy.

From bottleinamessage on Cruiser Log Forums 11/2007:
I'm on my third set in three years. I first bought two 130W Sunsei (ICP) panels from West Marine. Within a year both had corrosion forming under the glass and then one panel failed. When I removed them, the bottom of the panels were burnt and bubbled below the corroded areas. Returned them and got another set of the same panels. Within a year, same thing. Returned those for a refund and bought Kyocera panels. I would strongly suggest you avoid the Sunsei panels sold at WM.


SailNet - Kevin Jeffrey's "Charging with Wind Power"
SailNet - Sue and Larry's "Choosing and Installing a Wind Generator"
Article by Dick De Grasse in May/June 2004 issue of Ocean Navigator magazine
Fourwinds' "Wind Generator Comparison"
Wind Generator Comparison

Wind Generator characteristics,
summarized from article by Hal Sutphen in Sept/Oct 1997 issue of Ocean Navigator magazine:
  • Uses alternator or generator ?
    Generator has commutator (brushes): higher maintenance and more RFI.

  • Blade diameter (bigger == more output).

  • Current output at 14 volts or higher (12 volts is useless for charging batteries).

  • Minimum wind speed at which you get useful output.

  • How excessive wind is handled (braking or latching system).
    Some choices:
    turn sideways to wind and latch or lash blades (can be tricky/dangerous),
    friction brake (can burn out),
    air brake (may not be very effective),
    tilting the generator to spill wind out of it (requires lots of space),
    let blades flex to spill wind out of them (reduces effectiveness, increases noise).

  • How excessive current output is handled.
    Some choices:
    user turns off generator manually (unreliable),
    disconnect when battery voltage reaches max (blades may overspeed),
    shunt output to a dummy load (requires ventilation/cooling).

  • Thermal overload protection ?

  • Audible noise.
    Increases with blade size;
    increased by blade damage;
    may decrease as blades are added.

  • Vibration noise.
    Increased by blade imbalance;
    may be worse at certain wind speeds.

  • Radio-Frequency Interference (RFI).
    Generator worse than alternator;
    put filters on output;
    slip-rings and brushes in mount may cause RFI, especially if dirty.

  • Mounting options (want high to get good wind and keep away from people, but low to keep weight low).
    Some choices:
    hang from halyard/rigging (useful in port or at anchor only),
    on dedicated pole,
    on arch,
    on mast.

  • Ease of maintenance.

  • Intended use:
    How much power do you need from it ?
    What are wind speeds in your typical cruising area ?

  • Options (can connect to towed propeller ?).

Paraphrased from "This Old Boat" by Don Casey:
  • Self-exciting alternator: self-limiting (will not produce more than rated output, so won't burn out in high winds).
  • DC motor-generator: about 4x current for same wind, but unregulated (output will climb with wind, and may self-destruct in high wind).

Mostly paraphrased from "The Boatowners Mechanical and Electrical Manual" by Nigel Calder:
Speed control / braking methods:
  • Tie off the blades or tie the unit side-to-the-wind.
  • Centrifugally activated friction brake (WindBugger).
  • Centrifugally activated air brake (Fourwinds II, Neptune Supreme).
  • Furling or tilt-back mechanism.
  • Blades designed to flutter or stall at high speed.
  • Electrical brake (KISS).

From Jeff Smith on The Live-Aboard List:
Just to offer up some criteria by which I chose the unit that I bought:

1) How is it protected from high wind speed damage?

2) How noisy is it?

3) Does it have a built-in voltage regulator?

4) How available are spare parts where you cruise, or intend to cruise?

5) Does it have thermal breakers that will open when in heavy wind? This is bad IMHO.

6) How do you shut it off? Do you switch it off (short it) or do you have to tie it down?

7) Is it suitable for unattended operation on a boat?

8) Does it have a slip ring? In other words can it rotate continuously in the wind?

From Doug on Cruising World message board:
I have a 4Winds III which is absolutely quiet. Standing on the dock beside the boat I cannot hear it in 15 kts of wind, honest. Brian does make a good point. However, my experience in the Bahamas and SE US coast is that you still want enough breeze to keep the boat cool. That's usually enough to make use of my 4Winds. I like the idea of solar panels but don't know where I'd put them on my boat. I haven't solved the problem of downwind lack of apparent wind yet, but also haven't made a passage in this boat longer than 4 days yet.

From Rikava on Cruising World message board 7/2006:
... the KISS is a great unit. Right now we have a Fourwinds Red Baron ... it's a great piece of crap! Oh, it puts out as advertised which is very high even at low wind speed. That is if something doesn't fly off or fall apart. We had 4 complete prop assy's, 3 complete generator assy's and 1 regulator rebuild. All of this was within the first 2-1/2 years we had the unit. We at the present are not cruising but when we head out again we'll have the KISS on our stern. Right now our Red Baron has a main shaft that is frozen ... suspect bad bearing.

I'm only speaking for myself, but while out cruising I met a lot of other very frustrated R.B. owners. One told me that his unit is laying in 6000'; out of frustration he threw it overboard.

Just remember basicly warranties are really not much good while out cruising ... you need a reliable unit, not one that you are always waiting for parts, not to mention phone calls at a $1+ per minute.

From Logan S/V Scotty Ann on Cruising World message board:
They all make some noise and after a very short while, you don't hear it any more. We use an older model Rutland and find it keeps the batteries topped up nicely in the trades. We sleep in front of a fan each down there anyway, so we don't really hear it at all. When we do it's nice to know it's making amps. Really, the noise is white noise and after a very short time you just don't hear it.

From Dennis Plane on the WorldCruising mailing list:
I have a Airmarine wind generator and I'm more than satisfied with the performance. While the sound levels are easily put in the "general background noise" category, quieter is always better in my estimation. I have had good success with making the unit quieter by disassembling the fan unit and sanding off all manufacturing dags and making the blades aerodynamically clean (i.e. turbulence equals noise). I fine wet and dry sanded so that the blades were smooth, the tips were rounded and the trailing edges were sharp. I also weighed each blade and sanded so that they were the same weight to the gram. My unit now is noticeably quieter than other Airmarine units in the anchorage. My next goal is to rubber-mount the wind gennie mast to alleviate harmonic vibrations transmitted within the deck.

From Pierre on Cruising World message board:
Sand the edges of the blades (both) but be very careful. If you unbalance the blades you're in trouble! Did you check the blades for balance before you installed?? It's an easy check, just the same as for model airplane propellers. Take the gen down and manually spin the blades, mark the one that ends up vertical (down side), then repeat 10-20 times. There should be no blade that has many more marks than another.

On the rubber mounting pads ... throw 'em out. I've got mine hard-mounted, no vibration dampening, and the pole doesn't transmit to the boat. There is very little vibration to start with.

On the noise itself. All wind generators make noise, more noise = more power (more or less) so you get used to the sound of "free power".

Some noise can be caused by tail fin too small (blades not pointing straight into wind) ?

From Gene Gruender on IRBS live-aboard mailing list:
I have a little experience with the Air Marine and have cruised a bit and have dealt with and talked with their service people ...

First, all the talk of being an outcast if you have a wind generator is bunk. Of course, there will always be be a complainer, but some people would complain that their free beer was too cold. If you get out where there are cruisers who have been out for a while, I'd say 50% will have at least 1 wind generator. 10% or so will have 2. I've never noticed that 50% of the cruisers were exiled to the other end of the anchorage because they had wind generators. Most of the time, the wind generators are hardly turning, so it's no big deal. If it's blowing so hard that they are really humming, the wind in the other boats (without wind generators) will pretty much drown out the noise.

As to the noise that the Air Marine unit makes, there are a few things to be said. Up to about 25 knots or so, there is a whistling noise, much the same as wind rustling the leaves in a tree that you might be sitting under, increasing a bit as the wind picks up. Up to 25 knots, maybe 30, I haven't heard one that was much more noticeable than the wind noise itself at the distance most people would anchor.

On the boat it's mounted on, it can be a real problem with noise if it's not balanced, and I expect this is true with any wind generator. You MUST make sure your blades are balanced or you're going to have a LOUD noise transmitted into the hull of your boat. Sure, you can mount it into rubber, etc, and get it down some, but if it's balanced, it will be about the same as the wind noise.

They sell balanced sets of blades now (I really can't understand why it wasn't always that way - surely the other guys balance theirs) but they still aren't completely balanced. Shame on them! But you can take them to the post office (after hours, preferably) and balance them better. Using a file, get them to be the same weight for all three, and all the same weight at each end. It doesn't take much filing to do this.

Twisting, brakes and other rumors:

Where the noise comes in is about 40 mph of wind. When they start the "twisting to dump wind" they howl. LOUD. No argument. If you are nearby, you'll swear they are going to explode. Their literature says they can run to 100 mph of wind without a problem. Well, I found out otherwise. We got caught in a quick squall in Florida and it got to about 70 knots. It was putting out 40 amps and you could have heard it in the next county. It also lost chunks of the plastic at the center end, which put it back out of balance.

I talked to them about that and, in addition to sending me new blades to the Bahamas at their expense, they explained that they'd tested them to 100 mph with no problems. What they didn't anticipate was that in addition to the wind speed, there was the boat rocking back and forth, and the wind twisting around the rigging and all the other boat parts. This created turbulence that they didn't count on and they now say they should be shut down at anything over 50 mph.

Tying them off isn't practical. I can tell you, absolutely, that there will come a time that tying off the wind generator is the last thing you'll have on your mind. For that reason, you should install a switch.

And, to answer another question I saw in one post, you can short out the leads to stop it. Of course, you must first disconnect it from the battery, but when you hook the two output leads together, it's not going to do much turning. It just loads it up and it effectively becomes an electrical brake. They sell a switch for the purpose, but I'm sure you can use any double-pole, double-throw, break-before-make switch rated at about 40 amps.

Air Marine has one thing going for them. They have outstanding customer service. They understand who is paying the bills.

Having said that, I will add a second wind generator before we leave next time, but it'll be another brand because I think I can get more power than I'm getting from this one.

From Peter Hendrick:
SW Windpower Airmarine: broke after one year during warranty, great support from mfg.

From Greg Walsh on Cruising World message board:
My experience (circa 1995 on a 1 year cruise in Mexico and French Polynesia) with the Air Marine wind generator is fairly negative. Noisy and not much power unless you were anchored someplace you probably shouldn't be. Also the internal voltage regulator failed for no apparent reason and I had to replace it. To their credit, West Marine supplied a replacement regulator free of charge. I think your money is better spent on more solar panels than any sort of wind generator. We had two 50 watt panels on swiveling mounts and were very satisfied with the output. We wished we had more.
From Brian Woloshin on Cruising World message board:
I agree with Greg. I had a Four Winds II for four years and it was noisy and never produced the power advertized. I sold it and bought four additional solar panels. I have a total of six Siemens SM-55 panels on my Bimini. They are silent, no moving parts and the only maintenance is to clean them.

When you anchor, do you want a nice quiet anchorage or a windy one to charge your batteries?

From Dennis Biby on The Live-Aboard List:
BTW, even here on San Francisco Bay where the wind seems to always blow and the fog rolls, this winter, my solar panels have been a more consistent source than the wind gen.

From Cameron on Cruising World message board:
My wife and I have installed two Fourwinds II's aboard our boat. We are a family of 4 and live full time, at anchor, aboard our boat. Subsequently, and not trying to push, we have started a business and are dealers for the Fourwinds. That being said, I would not install anything that I wasn't willing to back up!

Our Fourwinds II run 24/7 and have never had an issue except usual maintenance (cleaning electrical contacts, etc). To give you an honest performance, low wind speeds are just getting the units started, this holds true with whatever brand you choose. However in about 8-10 kn of breeze we are getting about 6-8 amps of charge out of them (each). And in a good 12-15 kn I am showing about 12 amps. The air brake starts coming in to play at about 20 kn and fully open at about 30 kn. Like all wind gens at this wind speed they do make a little bit of noise as the air brake is disrupting air flow. They are warranted for 50 kn but I have had mine still running in 80 with higher gust (but that's another story). At that extreme wind speed I was getting a combined 40 amps of charge as the air brake would limit the blade rotation. The key to getting good output out of them is not to skimp on the wire sizing. ...
From Carl Bosek on Cruising World message board 7/2007:
I installed a Fourwinds II in April/May '06 along with its tow gen. I have not found performance to be as good as you describe in only 8 kts. I also have the air brake and have wondered if that hampered performance. In your case, apparently not. When I return to the boat in August I'll be doing some test charging and checking current flow into my battery bank. But I rarely see my in-line ammeter exceed 10 amps unless wind speed is 15 kts or better. However, I am reading output into my batteries, not into any kind of standardized dummy load. I have an ammeter in-line between the voltage controller and the battery bank and I also check with a clamp meter.

Two cautions with the FourWinds II -- don't ever use the electrical braking switch on the control panel because you will burn out the voltage controller; second, don't simply join the FW II with a tow gen in parallel. The tow gen tends to over-rev with its current configuration and it will exceed 30 amps when it jumps out of the water, causing the diodes mounted on the generators to blow out. My tow gen and wind gen were simply wired in parallel. I found that I should have disconnected the wind gen before running the tow gen. I plan to install a switch on the wind gen so this doesn't happen again.

The prop that came with the tow assembly was of poor construction and I had to replace it (with some difficulty). Also, the weight on the rig is inadequate to hold the unit below the surface. I had to improvise weight to add to the downrigger. A prop shaft zinc works well, but will erode away of course.

After I got the replacement controller installed this last April the wind gen seemed to be doing pretty well, but since I'm leaving for Tahiti in September I plan to be running several tests on the system in August.

From John on the SailNet carribeanislands-list:
I currently have an Air Marine 404 which is OK, but somewhat noisy and it needs 15 kts of wind to make a few amps. Of course at 20 kts of wind the amps go up significantly (exponentially).

Ampair is quiet and runs in light air. [But what is output at that speed ? Several people say Ampair gives little output.]

From Mike D. on Cruising World message board:
[Re: Ampair 100:] Out of the 11 people I've known with them, seven of them had to replace them because of different problems and the rest said that they just didn't do the job.

From Scott on Cruising World message board:
Ampair 100 - 7 years of experience:

I have been disappointed with the output of the Ampair 100 wind generator since day one. I originally had a regulator installed but eventually disconnected it because of the low output. However, as wind generators go, it is quiet. If I had to do it again, I would definitely purchase the one with the best performance at the lowest wind speed. I believe Air Marine fits that bill, but they are definitely NOT quiet.

"[Fourwinds II] ended up costing an arm and a leg when you start buying the centrifugal air brake, and other add-ons such as a regulator. ... it has burned up twice already in the two years I have owned it. ... I didn't buy their charge controller because it was another $260."

From David Romasco on the SailNet liveaboard-list:
... Be advised, though, that there is no such thing as a silent wind generator. My original WindBugger sounded like a damaged Huey (distorted composite blades); I had the unit rebuilt by Bugger Bob, and replaced the blades with solid aluminum flat blades. The sound level dropped and changed to a more livable tone. Where and how you mount the unit also makes a large difference. Transmitted vibration can equal or exceed the noise directly from the blades. I always found the dull hum to be the satisfying sound of power rolling into the batteries (lived on a mooring in St. Thomas for years).

Safety tip: paint (or tape) the blade tips a contrasting color. My new Bugger blades had yellow dots stuck on, which showed up on the black blades as a large and bright circle showing the area of danger when the unit was turning. I saw one boat that put that black/yellow striped safety tape down on the deck showing the danger zone. You may not be THAT safety-minded ...

From Roger Mummah on the SailNet liveaboard-list:
... I can't overstate the power of the wind generator. In the Bahamas, in the winter, the wind can blow 15-20 knots or more 24/7 (all the time). I love the Four Winds II 20-amp wind generator made by Everfair Enterprises in Punta Gorda, Florida. If you have 15 knots of wind all day and night, it will put out, lets say 5 amps per hour all the time. 5 x 24 hours is 120 amps per day (and night). ...

From Jeff Smith on The Live-Aboard List 7/2005:
I purchased an Air-X Marine Wind Generator about 6 weeks ago.

I am not in any way affiliated with the company that makes the unit. I am just a happy customer.

Here is a brief description of the unit, my reasons for buying it and my reasons for being happy so far with my purchase.

First off, let's talk about noise since that was a BIG worry to me.

Southwest Windpower Inc. makes the Air-X marine. They also used to make the Air 403 wind generator. The two look IDENTICAL to me, however appearances in this case are VERY VERY deceiving.

The old AIR 403 was LOUD as hell. In fact, in high winds, to me it sounded a lot like a chopper coming in for a landing and that is NOT an exageration. The reason is because on that older model, they used a technique for slowing it down in high winds that was noisy. What they did was make the blades flexible so that they would bend or "feather" and reduce power to the wind genny in high winds. The feathering made the blades go wop wop wop. LOUD enough to wake the dead. I would NOT want to anchor near that. I mean, within a thousand feet even. Southwest Windpower has a marketing issue now, since the new units look so much like the old ones, everyone assumes the worst.

The new Air-X marine unit is markedly different although it looks to be identical from the outside.

Here's how it works in high winds:

Inside the unit, there is a circuit board with a built in regulator. The regulator board is able to measure the wind speed (I suspect by measuring the output votlage). When the wind speed reaches about 35 knots, the board senses the high wind condition and slows the rotational speed of the blades substantially in order to reduce noise. At 50 knots the unit is said to get shut off completely, reducing speed to a gentle rotation. ...

At 20 knots of wind, while at anchor, it sounds about as loud in the cockpit as it would if you had a typical household electric fan blowing on the occupants of the cockpit to keep them cool. You can easily converse. ...

It is equipped with a slip ring, so can rotate 360 degrees as many times as you like. I felt that is important given that it is not easily accessible.

It has an internal voltage regulator. This is good.

To my knowledge it doesn't have internal thermal breakers due to the technique used to slow it in high winds. That issue is one that really worried me on some other units.

It's designed to be run without physical intervention. A stop switch can be installed (I did) to short it so that it is "off" and then virutall silent. I liked that a lot, since it was being installed in an inaccessible location (think up the mizzen) where reaching it to tie it down was impossible. Before buying I asked by email if I needed to arrange to tie it down ... ever ... and they said no, just use the stop switch unless winds are expected beyond 110 mph (!) then take the blades off.

I turn it off at the dock (shorepower instead) but leave it on at all times when off the dock. No matter what winds we get.

Output power as I measured it: In 10 knots of wind, it puts out about 1.5 ~ 2 amps @ 12 volts or so. That's about 18~24 watts watts. At 20 knots it puts out about 8~10 amps. It's hard to be exact with these readings though, since it isn't a steady output like a solar panel or charger puts out. My ammeter is digital so it introduces delay into the readings. But I am pleased with the output power.

It's lighter than many others, at only 16 pounds. I really like the idea of it not being too heavy up there.

Ease of installation: The hard part was running the #6 wires ... It was very easy to install and the manual is well written.

Suitability for an ocean environment remains to be seen of course. But they do have dis-similar metals holding things together (alumimum chassis, stainless fasteners for example). They obviously know that this could cause an issue and wisely choose to include a (small) tube of tef-gel with the unit and recommend applying to all fasteners during assembly. I am slightly concerned with respect to the die-cast, powder-coated aluminum chassis body standing up to salt air and water though. Time will tell.

Parts availability also remains to be seen. Since it is a popular unit I hope that parts will not pose an issue throughout the Caribbean. Then again I also hope that I won't need any parts either!

Technical support - I have not needed any support since installing it. Prior to purchase I emailed them 4 times to ask questions. They responded promptly and that is a good sign I think.

Cost - When deciding which unit to purchase, I put the cost of the unit at the absolute bottom of my list of important considerations. ...
From Ken James on The Live-Aboard List:
I can provide a bit more info on the Air X.

The regulator is a specific type of switch mode design. This means that it does not get hot. It in fact is a clever derivative switch mode design that changes the timing of its 'on' pulse relative to the current phase angle as well as the length of that pulse 'on' time, and the result is that by doing this it is able to not only be more efficient but also use generated power to slow the blades when needed without dissipating much power at all; that is to say not only does the regulator not get hot when regulating under normal moderate wind conditions, but it also will not get hot when it is slowing the blades! That is a very dramatic improvement in the technology. Other units use a 'shunt type' regulator that takes extra power and burns it off as heat, not only making a bunch of heat somewhere but also making the generator work harder, and BTW if the wind gets too high that scheme can't keep up and the generator will overheat or run away if not furled or stopped.

In 2010 in St Martin, I heard of several boats having problems with Air-X wind-generators. The symptom is that the generator stops for no apparent reason, then restarts a minute or two later. Very intermittent, may get worse over time, has happened on at least 4 or 5 units. One boater claimed to have found and fixed the problem: an overfastened and stripped screw inside the unit, near one of the brushes, that was causing an electrical intermittent. Seems to be a manufacturing error.

4/2010: Heard there is a recall of blades for the Air Breeze wind-generator: UV makes the original white blades disintegrate; manufacturer will replace them with new black blades.

KISS wind generator:
12/2012: I've heard that Hotwire has bought out KISS; manufacturing has moved to Florida, the Trinidad operation has been shut down.

3/2014: There now is a new, USA-made KISS, which is different from the original KISS. From item from Hotwire in 3/2014 issue of Caribbean Compass Magazine:
The US-made stator is wound tighter for less resistance, the US-made rotors are much more accurately machined, the rectifier is upgraded from 30A to 50A, and the thermal sensors and magnets are selected for higher operating temperatures, all for increased output, especially in higher wind speeds. The housings are now made with special resins and other materials that allow for higher operating temperatures, which increases the wind speed at which it will go into freewheel, the most common complaint about the original KISS. A newly designed yaw bearing at the base of the housing improves wind tracking and ease of installation. The blades are stronger, smoother, and have wear-protection on the leading edge. They come factory balanced and can be replaced individually. And a long-requested nose cone is included for cosmetic reasons. [Generator now costs $1500.]

From Robert Clemons on The Live-Aboard List 7/2005:
My experience with a KISS: I've had it for about a year now, but I've only used it on the hook a few times while traveling. I've run it at my slip a bit to test out power generation and noise.

I have it mounted on a post on the stern of my 36 foot boat. I sleep in the aft cabin and notice some noise in the form of vibration that comes through the hull. I believe the blades require a bit more balancing to get rid of the vibration. I don't hear it in the forward berth at all. Sitting in the cockpit, the noise is only slightly more than wind noise, so it's not an issue when the wind is blowing 20 knots or so. Can't speak much about 30 knot winds since I wasn't ever sitting in the cockpit under those conditions.

As far as power generation is concerned, it requires about 8 knots of wind to get any power, although it will spin at lower speeds. At 15 knots, it provides about 6-8 amps. At 20 knots, I've recorded 12 - 15 amps or more. At 25 knots and more, I get about an amp for each MPH. As was stated earlier, the power is not steady. It really fluctuates.

From Kenneth McKelvie on The Live-Aboard List 7/2005:
I have had the KISS for about three years now, having dumped the old model AirMarine because of noise nuisance to me and any neighbours. The KISS does need careful balancing on a windless day indoors before mounting the assembled unit - it took two attempts to get it right, trimming little bits off the lead weights till the blades were totally balanced. (I did this in the bar at the yacht club, balancing the blades between two bar stools, much to the amusement of the assembled, well-lubricated yachties!!) Result - no vibration and almost no noticeable noise and, as Bob says, any noise at higher wind speeds is effectively no more than that generated by the wind itself.

The wiring is directly connected to the unit, so it is limited in the amount it can turn on its mount otherwise the wires twist and break (a "high tech" length of cord stops it turning too many times) - best used on a swinging mooring, at anchor or under way rather than on a marina berth. It is not a pretty machine, but all its parts are readily available as there are few, if any, specially manufactured components - most are widely used in car battery charging systems etc and can be obtained almost anywhere in the world.

I get a bit more than 8 amps at 15 knots steady breeze - sometimes nearly 10 - temperature seems to be one of the reasons for variation. Not sure if it is the heat on the KISS or heat in the battery compartment that seems to reduce the recorded amp output.

Great support from the guy who manufactures them too - one of the blades cracked when I first installed it - he sent out a new set to Hong Kong from the Caribbean where he is based within a few days.

From various people on SSCA Discussion Board:
KISS wind generator:

From RBEmerson:

The first issue is the thermal cutout. It's a good idea but there's a problem with the way it's implemented that, IMHO, makes leaving the KISS running while unattended risky. Specifically, if the wind speed comes up, the batteries are charged up, and things get, literally, too hot, a thermal cutout protects the coils. So far, so good. But now it's not possible to use the electrical brake to stop the blades from turning, because the thermal won't let the brake work, either. All that's left is to manually turn the rotors parallel to the wind and grab a blade, after things slow down, to tie up the rotor. All of this manageable if someone's on board and they're not busy doing other things because the wind's come up.

The second factor, which isn't a problem, per se, is the KISS wind turbine is tuned for use in the trade winds. If that's where you're headed, fine. However, we're likely to spend more time cruising the US East Coast. And even when we have sailed where the trades blow, we've looked for anchorages that offer at least some shelter from the wind, something the KISS design doesn't use well.

From Louis Riel:

Top of the mizzen is a bad location for the KISS. It is too hard to tie it off in a gale, and the electronic shutdown won't stop it from burning up in a gale. A client, while returning from Hawaii, was suddenly hit by hurricane-force winds. The electronic shutdown was nowhere near strong enough to keep it from turning, and smoke billowed out of it like a chimney. It burned to a crisp before he could stop it.

From LeeC:

The KISS distributor in the US tells me total cost with wind generator, mizzen bracket with vibration isolator, charge controller and diversion load, wiring, etc, is about $2000.

From Don Radcliffe:

No brushes, so much less maintenance, and no HF radio interference from sparking brushes.
[Older Four-Winds have brushes; newer ones don't.]

From mlc101:

Biggest problem with the KISS is the thermal cutoff noted by others on this thread. At 15 kts, it produces lots of usable power. By perhaps 23 or 24 kts of wind, the thermal cutoff will occasionally shut down the unit. When it shuts down, it FREEWHEELS, and the shutoff switch does nothing. You have to rotate the unit by hand, stop the blades and tie them off. I believe it would be possible to wire the unit so that the switch shutoff would work even after thermal shutoff, and have suggested that to Doug, but not heard from him about it.

From salesman at Island Water World in St Martin 11/2009:
He's had one on his boat for a year or more.

No charge-regulator needed; just connect it straight to the batteries. The KISS never puts out more than 14.2V. Makes up to 25A in strong wind.

If you wanted to have a regulator, the same ones used for solar panels will work for wind-generators.

The generator is producing AC, then diodes in the switch-box rectify it to DC before going to the batteries. The diode block in the switch-box can get pretty hot; install the box with decent ventilation (don't cover it up).

Having a mast-bracket made is pretty easy. The generator comes with a pipe-top adapter, designed to sit on top of a pole. Have someone make a bracket that has that adapter sitting on the end of it.

My KISS experience:
I bought a KISS wind generator and KISS mast-mounting bracket in 1/2010.

Feedback to KISS:
  • Manual should give weight of unit.

  • Manual should show side-view of unit and give various dimensions, especially for those designing custom mountings. Would be nice to have some words about mounting on mizzen mast, even if mizzen mast mounting not bought from KISS.

  • Mention what to do if only metric pipe sizes available.

  • What is 10-24 tap for ? Instructions list it as a required tool, but never say to use it. (I used it on holes in pipe to hold grey PVC cap in place.)

  • Web site should give more info on mizzen-mast mount: dimensions, especially max mast diameter.

  • Instructions should give info on preventing vibration from getting to hull, both when using pole mount and when using mast mount.

  • One part of web site says mizzen-mount costs $245 plus shipping, order form says $145 plus shipping, invoice says $140 plus shipping.

  • There were no white paint marks on switch terminals on the unit delivered to me.

  • On the switch terminals on the unit delivered to me, one of the screws wasn't grabbing properly. Swapping with the screw from the unused terminal fixed it.

  • Mounting holes in mizzen-mast bracket are very close to the edges (3/16"); would give a little more confidence if they were maybe 1/4" further from the edge. Maybe not a problem; I don't know much about metalwork.

  • One of the cap-screws to fasten the grey PVC cap in place was the wrong size; one was 10-24, but the other was thinner and probably -32.

  • Instructions probably should say to use Tef-Gel or something if putting stainless screws into aluminum pipe to fasten grey PVC cap in place.

  • Instructions probably should say to avoid having drilled holes intersect vertical spring-hole when drilling holes to fasten grey PVC cap in place. Maybe not a problem.

  • Threads on outside of white PVC collar and inside of generator housing needed a lot of work to make them mate smoothly. Most of the problem was on the PVC: big casting-ridge interfering with the threads. Instructions probably should say to dry-fit everything a couple of times, concentrating on this issue, before getting everything up the mast or on top of the pole and finding out there are mold-flaws in the threads.

  • Instructions probably should say to lubricate inside of white PVC collar so it rotates smoothly on the vertical pipe/pole.

  • Instructions should say what parts of grey cap should be lubricated. Every exposed surface ?

  • When generator is mounted to mast via bracket, it can't spin 360 degrees. On my boat, to clear the rigging, generator is mounted up out of reach from deck, even with a long boat-hook.

    If the boat is fixed in place (can't rotate to face the wind), and the generator gets back-winded, theoretically the hub-and-blade assembly could spin right off and come crashing down. Some situations where this might happen: boat anchored but pinned in place with a stern anchor; boat in marina slip; boat on the hard in a boatyard; boat sailing downwind.

    Or does the shape of the blades mean that they won't spin if the blades are back-winded ? If true, please say so in the instructions.

    How to prevent blades spinning off if back-winded ? Would be nice to have a cotter-pin hole drilled through the generator shaft near the end. Maybe some words in the instructions about installing a lock-nut ?

    Response from KISS:
    You have use some silicone sealant on the shaft and gave the blades a shove with your hand to set it on the shaft. Once the silicone cures this locks them in place.

    The blades will turn backwards but only at maybe 2 RPM so there is not much force to spin the blades of the hub.

    It has happened twice to my knowledge. One time the couple had just mounted them and acknowledged that they didn't tighten them. The other time a friend put the unit up for a lady friend and was adamant that he did everything by the book. (I thought he protested too much.) But she got a new set of blades and hub none the less.

    Okay, I used Tef-Gel, not silicone, on the shaft threads to keep the hub aluminum from galling to the shaft steel. Didn't realize there was supposed to be a "locking" going on there; maybe the instructions should say that the silicone is for locking as well as corrosion prevention. Maybe I'll add some sealant on the exposed part of the shaft; I don't think I want to put it inside the hub threads, since that would make it pretty hard to get the hub off when I needed to.

  • On my boat, with generator mounted via mizzen-mast bracket, I decided to remove the torsion-spring that seats into the grey cap. Damaged the spring once while dry-fitting the generator onto the cap, and the bent spring damaged the cap a little (sliced a little off it when I rotated the generator by hand). Very hard to get everything aligned right while 20 feet up a mast, trying to put generator onto end of bracket sticking 2-3 feet in front of mast. And line to tail of the generator will keep it from rotating more than 50 degrees or so anyway.

  • Concept of rigging wire and swage fittings that came with mizzen-mast bracket seems a bit unclear. I guess you're supposed to pry open the thimbles, slide the openings through the holes in generator tail and bracket, use pliers to close the thimbles tight again, then run the wire through and crimp on the swage fittings ? But I guess I'd have to do most of this while up on the mast, since I'm putting the bracket up first, then bringing the generator up later. And if I ever need to bring the generator down later, I'd have to cut the wire or something. Maybe the instructions should say to use an eye-bolt into the bracket ? And maybe a shackle through the hole in the tail ?

  • I think you're expecting use of 10-gauge wire from control box to batteries (supplied connectors seem to imply that). For my boat, with 9 feet from box to battery switch, if 20 to 25 amps flow, wiring charts recommend either 8 or 6-gauge wire; I used 6-gauge. Instructions probably should say something about this.

  • Instructions probably should say that diode block in control box can get hot, so mount the box in such a way that there's decent ventilation, or at least don't cover up the box.

  • I just read somewhere that once the thermal breakers have tripped, setting the switch to "off" for electrical braking does nothing. If this is true, the manual should say something about it. Since my generator is mounted 20 feet up the mast, I can't reach it to turn it sideways or something. I guess the cure for this is: if you expect very high wind, set the switch to "off" for electrical braking before the thermal breakers get a chance to trip ? And if you get past the point where the breakers trip, turn the switch to "off" so as soon as the generator cools and the breakers reset, the braking will take effect ?

  • I soon found that the occasional high voltage put out by the wind-generator causes a problem with my solar panel controller (Morningstar ProStar PS-30). The solar controller considers more than 15.3 VDC at the batteries to be some kind of fault, and does a "high voltage disconnect" (stops letting the solar panels charge the batteries). You might mention this in the manual, in the "Don't we need to regulate ?" section.

  • The "Don't we need to regulate ?" section probably should say that it assumes the wind-generator is the sole charging source. If you also have solar panels, uncontrolled charging probably will lead to overcharging.

  • The "Don't we need to regulate ?" section might mention that four 6-volt golf-cart batteries add up to about 450 AH at 12V. And a similar example using 12-volt batteries. Some simple examples would give a clearer idea of what 500 AH represents.

  • The manual should say the maximum VDC the generator will produce. I've seen up to 15.95 VDC so far. Another user said he'd seen up to 17 VDC.

Sent the whole list to KISS, and got no response.

More of my experience:
  • I was able to buy the generator in stock from a store, but had to order the mast-mount bracket directly from KISS. This turned into a 6-week ordeal; sometimes KISS responded to email immediately, and other times email went ignored for a week or more. Phone calls sometimes reached someone knowledgeable, but often not. Had to submit my order twice; I suspect they got behind and simply deleted their existing email and web orders (totally a guess). A specific promise to ship "by the end of this week" turned into "end of next week". A promise to send email with FedEx shipping info was not kept.

  • The mast-mount bracket comes with only two holes drilled in the end that fastens to the mast, and the two holes are pretty close to the edge of the bracket. So I drilled a third hole, to add some assurance.

  • I added some rubber sheets between the mast-mount bracket and the mast, to try to get some vibration isolation. Not clear how helpful this is, since the bolts themselves fit very tightly in the holes in bracket and mast, transmitting vibration that way.

  • I tried to put a couple of lock-nuts on the shaft, to prevent the hub from spinning off in case the generator is back-winded. 5/8" nut fits on hub threads. But once blades are fastened onto hub, only one 5/8" nut will fit, with almost no room left on the shaft for seizing wire after the nut. KISS says using silicone sealant will lock the hub onto the shaft. Soon I got rid of the 5/8" nut and just used seizing wire, trying to get it tightly into the threads, and then tight around the rectangular section on the end of the shaft.

  • I drilled an additional hole in the tail of the generator, and used two tether lines instead of one. And I put shackles through the holes in tail and bracket, to avoid chafing there. Since I'm using a mast-mount bracket, failure of the tether line would result in the blades destroying themselves against the rigging.

  • After a month of using the generator, I find: it's quieter than I expected, it takes more wind than I expected to get it to start turning, and it takes a lot of wind to get serious current.

  • I like the fact that the control box is so simple and uses standard components. But the terminals are a little close together and I worry about shorts to the aluminum box, so I added some electrical tape and liquid tape in a few places (I'm probably being overly cautious).

  • A new set of blades will cost close to $200; seems a bit high.

  • I've seen the generator put out up to 15.95 VDC.

  • I've seen the generator put out 29.5 A at 15.2 VDC. 30 A seems to be a hard limit, imposed by the diode block, I guess.

  • Takes a lot of wind to get serious current out of the generator. On a fairly windy, very sunny day, I think I get more energy out of my 240 W of solar panels. But then of course I get power out of the wind-generator at night.

  • Later found that the occasional high voltage put out by the wind-generator causes a problem with my alternator regulator when the engine is running: the regulator gets confused and stops putting out current, making the tachometer drop to zero. When the wind-generator slows or stops, the tachometer suddenly jumps back up to show engine RPM.

  • After a couple of months of use, I'm not sure I've ever heard the wind-generator thermal breakers trip. I expect to hear a sudden higher pitch from the blades. Since I get most of my power from solar panels, maybe the wind-generator has never worked hard enough to trip the breakers. [After 6 months of use, I've had them trip a couple of times, on days with sustained 20+ wind. Generator really runs roughly when breakers trip and un-trip; I wonder if there is a breaker per tap, and they don't all trip/reset simultaneously ? Blades are noisier when free-wheeling than when generating power. I'm guessing it's a bad idea to throw the control switch to "stop" while the blades are freewheeling with the breakers tripped; might produce a lot of unbalanced loading when one breaker resets and suddenly applies a shorted load to one tap ?]

More of my experience:
After 2 years and 4 months of light use (I turn the generator off during the day, when solar is available, and often have little wind at night), the generator stopped spinning. Took it down and took it apart, and found that the front bearing on the shaft is very rusty and almost frozen. And there's another, smaller, also rusty bearing pressed into the cap; I didn't know about that one (it's an oil seal; hard to obtain).

Someone suggests replacing with ceramic bearings, to avoid future rust, but they're expensive ! 6203-2RS Full Ceramic Sealed Bearing 17x40x12 ZrO2 Ball Bearings ($90 each).

Sent email to KISS with several questions about this, and got no response.

There's a translucent rubber insert near the front bearing; no mention of this in the manual. It gets pressed/forced into the recess near the oil seal, tapering toward the rear.

I couldn't get the guts of the generator out of the housing; had to take it to a machine-shop.

Boss in the machine-shop has seen a lot of KISS generators, and has never see one like mine with a "drain-hole" in the front cap, about an inch below the main shaft hole. He thinks water came in through there, and recommends sealing that hole. I bought the generator new and didn't modify it; that hole was put there by the manufacturer.

Turned out the back bearing didn't need replacement. And that was the one that was so hard to get to that I had to take the unit to a machine-shop.

I sealed that "drain-hole" with caulk before re-installing the wind-generator on the mast.

For a while after the bearings were replaced, the blades didn't turn when wind got up to the usual starting speed or a bit above that. I was worried that the new bearings were seized or something. Climbed the mast while the wind was gusting around starting speed, and spun the blades a couple of times by hand. Then a gust caught them and they spun normally for 30 seconds or so. After a few days of spinning in higher wind, the new bearings seemed to settle in or something, and now the blades spin at a reasonable starting speed again.

Six months later, generator is making grinding-bearing noises again !
From Hotwire:
"Maybe you need a new bearing seat. If yours is black rubber, it should be replaced, because it could allow the front bearing to go off center, which might allow water to get past the seal."

From Hotwire:
"The weep hole from Trinidad does not angle downward. I would recommend drilling one that angles down at 45 degrees."

From Geoff Schultz, 3/2004:
I just experienced a failure of my KISS wind generator of a nature that I've been worried about for quite some time. The KISS generator has a thermal breaker on each of the 3 outputs of the generator. These open when the generator is getting too hot by generating too much power. This sounds OK in principle, but the problem is that when the breakers open, the blades freewheel at a very high rate of speed. The power curves that KISS supplies shows the generator producing 18 A at 20 Kts and 25 A at 25 Kts. However, there's nothing in their literature which shows the maximum sustainable power output.

A switch, located between the generator wiring and the connections to the battery provides a method of feathering the generator by shorting the outputs to ground or each other. In winds of less than 25 kts this typically causes the blades to spin at a very slow rate of speed. However, once the thermal breakers have tripped, this switch does nothing. To me this is a serious design flaw. The system should feather itself instead of letting the blades freewheel.

I first noticed this on the trip from FL to Guatemala last summer. I had just installed it and was quite surprised when it wouldn't feather in a squall that blew through. I contacted the US KISS distributor about this, and their response was that I should take a boat hook and use it to pull the generator sideways into the wind via a string that goes from the tail of the generator to the support pole. Yeah, that's a great concept until you're at sea with the boat pitching all over the place and probably a lot of other things going wrong at the same time.

Today we've been at anchor at Lighthouse Reef in Belize with a cold front blowing through. The winds have been in the 15 to 25 kt range all day. This morning the breakers tripped twice when the winds gusted over 30 for brief periods of time. Each time I was able to grab the string and swing it around to feather it. This afternoon the winds have been in the 15-20 kt range and the breakers have tripped twice. We were only generating about 17 amps sustained when this happened. The second time I was pulling the generator around when the string got caught in a blade and yanked the boat hook into the tail, snapping it off. I suppose that this is a lot better than having the boat hook strike a spinning blade and potentially impale me, but I'm not happy at all.

While in general I am happy with the KISS generator's simplicity, I think that this is a serious design problem which poses a substantial safety risk. If you're thinking about getting one, consider this fact before buying.

From Skip Gundlach / Flying Pig on liveaboardonline mailing list:
... it seemed that our unit wasn't performing up to snuff, particularly in that it didn't turn in the same level of light winds as before.

... taking the control switch to the workbench, and diagnosing with a multimeter, I discovered a tiny bleed-over between poles of the switch in the "on" position. That would negate some of the power, and, even, tend to make the system think it was "off" - a condition which causes the blades to turn very slowly in high winds, without generating power. Ooops!

From Norm / Bandersnatch on liveaboardonline mailing list:
Since you mentioned you had the unit apart to check the bearings I know you are familiar with the insides of the machine.

You mentioned "special circuitry" to prevent overheating in high winds. The "special circuitry" consists of simple thermal switchs (they look like giant transistors) on two of the three phases of the alternator. These switches are connected using 1/4" quick-connects, then covered with copious amounts of shrink-wrap, making a heavy, unsecured lump supported only by the wires connected to them, which includes the solid copper wires of the stator windings. When the normal vibration of operation is applied to this heavy gob of matter it is inevitable that the stator wires break, which happened to me several years ago.

I discovered the problem after noting low to no output to the batteries. When I checked the actual three-phase AC output of the units I discovered no output on the phases with the broken wires.

My cure was to remove all the shrink tubing and the quick-connects and solder the appropriate wires directly to the quick-connect tabs on the heat switches. I put a piece of normal (the original was a very heavy wall material) shrink tubing on the thermoswitch then lashed it to the stator with fishing line.

From Skip Gundlach / Flying Pig on liveaboardonline mailing list:
In hurricane-strength winds, I'd remove the blades, put a funnel over the front, pack the spout with something water-resistant, tape it shut, and tape the funnel to the nose, on svhotwire's recommendation.

Retailer says this 6-blade-and-hub product works on KISS and gives 30% more energy: HWB6D.
From Robin Wilson on Facebook 2/2012: "I haven't seen any performance improvement other than it seems to be quieter which is great! Better finish on the blades, helicopter tape on the leading edge and not so much balancing weights as the old ones."

From Cruiser Log Forums 6/2005:
Why I would not put another wind generator on a boat:

Specifically, the Southwest Power Air Power Wind Turbine, AIR-X or AIR-404/3. Noise: Everyone complains about the noise, at anchorages, crew complains underway, they make a moaning noise that is very disturbing especially if you are trying to sleep in a cabin under the generator. Power Generation: They produce amazingly little power. They require at least 15-25 knots of apparent wind to produce any meaningful power. They don't produce power at anchorages because most anchorages by their nature are in low-wind areas, they don't produce power going downwind because the apparent wind is often low. They don't produce power at the dock because you will [?] of the noise. They only produce power going up wind in a pretty good wind. Go slow: The wind generator and mast provide a pretty good wind profile and hence wind resistance.

Southwest Power's air turbines are not well built for the salt water marine environment and require significant maintenance. The Aluminum components like the generator body and mast tubes are powder-coated aluminum. After a few years the coating comes off in big potato-chip-like flakes. I sent mine back once and have had to paint it twice in five years. I put the mast tubes in heat-shrunk tubes which has worked well and they stay white. The generator body has to be painted about every year. The Stainless Steel (SS) hardware that Southwest uses is 304 SS not nearly as good as 316 SS which means that it is prone to rust and leave streaks on the deck and topside. I have removed these and bathed the hardware in mild solution of Oxalic acid which removes the rust stains and the rust from the hardware; this must be done two or three times per year.

In summary don't put a wind generator on your boat, and not a Southwest Air Power turbine. Based on my experience the more solar cells the better.

From Bill Morris in 2008 Ocean Voyager from Ocean Navigator magazine:
In wind generators featuring electronic braking, watch for pre-regulation, or the premature slowing of wind turbine due to another source voltage (such as solar panel output) being read as battery charge state. Though harmless to the controller and other components, pre-regulation can lead to less-than-optimum charging.

Rutland at e-Marine
Wind generators at e-Marine
Eclectic Energy D400 wind generator (also D400)
LVM Aerogen 4 (about $800; 1A at 10 knots; 3A at 15 knots)
LVM Aerogen 6 (about $1200; 2A at 10 knots; 7A at 15 knots)
Air-X Marine (about $1000; ???A at 10 knots; ???A at 15 knots; built-in regulator ?)
SuperWind 350 (about $1500; ???A at 10 knots; ???A at 15 knots)

Regulator (AKA "charge controller") may be required:
If you have a regulator, a diversion load is required:
from Coleman ($10 to $120).

How a regulator would work with a KISS wind-generator:
KISS wind-generator sends three-phase AC down three wires from generator to switch to diode block. Diode block produces DC, to batteries.

If standard regulator with a DC diversion-load is used, it would be used on DC side of the KISS diode block. So when batteries are full, KISS continues to spin, diode block continues to put out amps, and the DC amps get sent by the controller to be absorbed by the diversion load.

Would be much better: when batteries are full, controller shorts out the three AC wires to each other (that's what throwing the KISS's control-box switch to "off" does). KISS stops spinning, no AC current generated, no DC generated. No need for a diversion load.

Maybe there is a way to make a controller throw some relays to short out the three AC wires to each other ?

Non-marine or build-it-yourself wind generators:
Windpower wind generator
"How I home-built an electricity producing Wind turbine" by Michael Davis

Blade kits from Thermodyne Systems

From Brian Engelke on the SailNet liveaboard-list:
Re: our DIY wind generator:

Just to show you all how easy this was: generator pics

Body of generator - scrap acrylic plastic = vane blade
1 1/2" pvc and cap = vane blade arm
4" PVC and cap = motor body and end
scrap metal box fan hub = blade hub
1/4" x 3" x 24" wood = blade
scrap 2" whisker pole stock = mounting pole
scrap bimini 7/8" aluminum stock = mounting pole struts
scrap 30 VDC permanent magnet tape drive motor = generator motor
scrap industrial strength caster = pole/body swivel

The scrap motor came from for $20. These motors are great and charge at very low RPM. The rest of the parts I either had or bought on sale and it totaled $95. I studied blade design on the web and carved and sanded those from scratch. For this motor, the sweep area of the blades showed that the blades needed to be 24" long and tapered so the balance point if holding one on your finger should be 25%-33% from the mounting end to the outside tip. This keeps the centrifugal force working for you as opposed to slowing the blades down. I also used a postage meter at work to sand them until they were within .05 ounce of each other so at higher RPM they don't create vibration and tear the whole unit apart! I am no genius, so anyone can do this! The hardest part was definitely trying to get the mounting pole level straight up and down on a rocking boat!!!


SailNet - Kevin Jeffrey's "The Amazing Power of Water Generators"
SailNet - Mark Matthews's "Water Drive"
SailNet - Denis Glennon's "The Propshaft Alternator"

Towed propeller can be bad:
  • May surf/tangle when sailing downwind or with following seas.
  • Retrieving it can be difficult (tangles/knots).
  • Interferes with trolling a fishing line, especially if you get a fish on the line.

Alternator on propeller shaft, from Dave George on Cruising World message board:
I have had one for about 12 years.

Water is much denser than air, so more able to turn an alternator than the wind is, so quite efficient. I get all my power needs while sailing from the PS Alternator. I have a fairly large 3-bladed prop, so I figure I might as well use some of the drag. It does slow the boat down slightly to run the alternator, around 1/4 - 1/2 knot.

You get effective power starting at around 3 / 4 knots of sailing speed.

Some people worry about transmission lubrication. I have used one with a Borg Warner Velvet Drive, a Paragon, and my present engine has a Hurth Gearbox. I believe the main question is with hydraulic boxes, that only pump oil to lubricate the bearings when the engine is running. Borg Warner told me they had never seen a problem from allowing the prop to free-wheel. Paragon told me their gearbox was designed so that the bearings would always be lubricated. In neither case did I have a problem with the gear box. The Hurth is a mechanical box, so no problem.

I don't know about the cost these days. I bought the two I have owned (two boats) in Australia, the last one around 10 years ago. I think the gentleman who made them has gone out of business.

Essentially he used an alternator designed to work at low speeds. An automotive alternator works at roughly 2,000 - 6,000 RPM. I have a 10 inch pulley on the prop shaft, and a 2 inch one on the alternator. At best I get around 1500 RPM. I don't know if you can buy alternators, specifically wound for lower RPM's, but that is the first thing I would check on if contemplating rigging up a PS alternator.

Then you need to make sure you have space for the large pulley on the shaft, and a place to mount the alternator. If you can make it work, I think they are great.

From Ken James on World-Cruising mailing list:
Car-type alternators are not all that efficient, and the power curve is wrong ... better choice would be a perm mag brushless model, look in some of the alt energy sites ... but you will need to be going at least 5 kts before you get much out of them even. To do it right you also need a different prop, or you will not get even close to max potential.
From Barry Brazier on World-Cruising mailing list:
The guy in Oz who sold kits for prop-driven generators rewound car generators so they operated at slower revs. He got 15 AMPs at 5 kts.
From Ken James on World-Cruising mailing list:
What I mean by saying it is the wrong curve is this: it doesn't matter if you rewind it to produce more power at slower speeds, the problem is still inherent in the design in that if you make it produce good power at one speed, it will not do so at other, in this case slightly slower, speeds.

This is a well-recognized problem with earlier wind generator designs, and is one reason you do not see them using car alternators. In wind that pushes my boat 5 kts my wind generator can put out a lot more than 15 amps, so a [prop-driven] one should be able to also and still do good at 2 kts and 6 kts. But not with a car alternator, rewound or not; the power curve cannot be made to match the available power.

Towed propeller, from Paul on Cruising World message board:
... I don't think any of the water units put out much current until you get 5 knots, or better yet, 6 kts. The problem is the propeller. You need at least an 8.5" - 9" diameter with a 5" pitch ... hard to find. Commercially built units are completely overpriced as far as I'm concerned ...

From Matt on Cruising World message board:
REDWING Wind and TowGen:
We have been using the redwing 16 months. 6 amps at 6 knots. Hoist in the rigging to use as wind generator. 100 feet of line with a shaft and small prop. Downwind Marine in San Diego Sells them. It mounts on a gimballed bracket on the stern, port side. Yes you can fish with it. Just make your draq line a bit shorter. Caught a 25 lb. Dorado with the tow gen out and a big rapalla out on the drag line (meatHooK). Very happy with the setup. Only use the wind generator when we need to at anchor, more now as the sun is low. Also much quieter than a fixed mount unit.

From Gennaro Sammarco on YahooGroups liveaboards mailing list:
... 'Acquagen', a prop that you tow to make electricity. Once moored, you can rig (is an option) and transform her into a wind generator. In a magazine (Yachting Monthly or Practical Boat Owner, I have to check) there was an evaluation of different devices, but this was not very highly rated, because of the low volt output and loss of speed, up to 1/2 or 1 knot, along with the easy possibility to foul the prop or having her taken by a fish.
From Nick Leonard on YahooGroups liveaboards mailing list:
I used an Aquagen (sp??) and it is just as you say. Wotta pain. 3 amps claimed output but I don't think I ever saw that. Sold the silly thing to someone who insisted their daily consumption underway was less than 15 APD. Yay solar panels!!

From Thierry on Cruising World message board:
I have limited experience with Ampair's Aquair 100 unit. They claim that it puts out approximately 1 amp per knot of boatspeed, which matches my experience. I carry a spare turbine, and have never lost one so far. The turbine is painted black, which may reduce its attraction to sharks, but the paint seems to wear off after a while at the tips. Don't forget to take in the turbine before you start the engine, or enter port. With boatspeed of over two knots you need to heave-to before you can retrieve the turbine. Under two knots I use the old Walker Log method: unclip the towing line from the generator, then stream this end all the way out while quickly retrieving the turbine; this will prevent kinks in the line. Keep the two ends separate while you do tyhis, otherwise you will end up with a huge mess.

Redwing Towing.
Aquair Submersible Generator
LVM Aquagen 4 (about $900; 1-2A at 4 knots; 4-8A at 6 knots)
Ferris Waterpower 200

Regulator is required:
LVM regulator (about $200)