on a boat.
||Please send any comments to me.
This page updated: March 2010
Genset (Generator) section
Inverter (DC-to-AC) section
Shore Power section
Ways to get high-power AC:
- Shore-power connection.
- High-output modified AC alternator on main engine.
- Genset (generator set).
Genset versus Using Main Engine:
Using Main Engine
- Dedicated engine is smaller than main engine,
so uses less fuel, gives less noise and vibration and heat,
and runs at a more efficient load point.
- Wear and tear occurs on an engine that should
be cheaper to repair/replace than main engine.
- Running main engine at low load typical of
battery-charging is damaging to main engine.
- Having two engines gives some redundancy.
- Genset is very expensive.
- Genset takes up additional space, and adds
weight (probably in a bad place, too: lazarette).
- Genset is yet another system to maintain, stock spares for, etc.
- Genset usually gasoline-powered, causing safety
issue and requiring separate fuel tank
and additional weight.
From Gary Elder:
I have seen many people install gen-sets after setting up their 12 volt
systems around a big inverter and high output alternator.
Fabco Belt-Driven Generators
From Arild Jensen on The Live-Aboard List:
> My new Iota 55A charger has started
From Lew Hodgett on The Live-Aboard List:
> blowing polarity fuses.
> I enquired with the local Honda service facility,
> and they suggested that the inverter technology might
> be the reason for the open ground.
Inverters generally have a situation with "open grounds" unless they are
wired according to ABYC standards.
This is the big factor that distinguishes "marine" from other use inverters.
A normal non-marine inverter has a floating output; meaning neither line is
connected to ground.
Marine applications require the AC system to be "polarized" and the
designated neutral must be tied to ground.
In the case of a portable Honda genset this is not feasible for obvious
reasons. However as soon as you connect it to a boat system you end up with
problems (one more reason why the use of portable gensets is discouraged on boats).
Your IOTA charger evidently looks for a potential between the green ground
lead and the negative output lead.
I haven't seen a schematic so have to make an educated guess.
The solution is to have a ground connection from your white wire neutral on
the genset to your vessel AC grounding bus.
However when you connect to shore you MUST disconnect this ground strap or
risk accelerated corrosion due to galvanic or stray currents circulating
through the shore power cord.
I do not know if connecting such a ground strap on your Honda EU generator
wil create any effects or problems for the Honda safety circuits or self
If you never connect to shore power this may not be a problem.
Another fine example of why an isolation transformer should be installed.
From Karl Denninger on The Live-Aboard List 12/2002:
Re: Genset recommendations:
I went through this last year.
Gig had an old 8 kw Onan that had an electrical end go out - I could have
had it rewound for about $3,000 or so, all-up, but then I'd still have a
tired and loud engine. She was burning a good bit of oil and while it
was able to produce full power, it was loud and just plain ill-mannered.
I looked at Westerbeke, Northern Lights, Onan's current line, Panda and
The Kohler won.
A year later now I am completely happy. It's QUIET - in fact, much quieter
without a sound-shield (I didn't buy one) than my old Onan was WITH the
sound-box! I can BARELY hear it over the AC circulating fan in the master
stateroom (adjacent to the engine room) and can't hear it at all from the
guest (forward) berth.
It requires no preheat and starts instantly. Even when the outside air
temperature is 40 F (I haven't tried in colder outside temps yet).
It is more fuel-efficient than the old Onan, burns almost zero oil between
changes, and in fact doesn't even get the oil very dark - unlike the
coal-black oil that used to come out of the Onan, and DOES come out of my
mains. The oil analysis reports coming back on it is so clean I wonder
if it's a gas engine down there sometimes!
The engine is a 3-cylinder Yanmar and sounds like a sewing machine when
it's running from the cockpit.
The best part? It was no more expensive than the 'Beke or Northern
Lights (in fact a bit cheaper than those two), was a LOT cheaper than the
Panda (like less than HALF as much!) and has the best warranty (5 years
or 2,000 hours in recreational service, INCLUDING labor to remove and
replace) of any of them.
Panda claims to have the "best warranty in the business."
Horsecrap - Kohler beats them hands-down on that account.
If I was doing it over I'd buy the Kohler again in a second.
I am completely satisfied with my purchase, and have over 350 hours on
its clock thus far.
From Margaret Pittelkow:
I have had 2 Kohler gen sets, both nothing but problems.
I am on my second Kohler 5.E generator. The original 1999 generator
had numerous issues and was
eventually replaced in January of 2001. Not by Kohler.
The second generator has followed the same path.
Since its installation I have had numerous issues ranging
from bad sensors, to having to replace
the carburetor and starter.
After logging more repair hours than running hours, the
repair shop stated that it appeared that
the generator was taking in water. They had found small amount of water in the oil.
The Original generator had a siphon break; when the new
Gen Set was installed a siphon break was
not included as it should have been. The repair shop
also found a faulty Factory Kohler fuel
filter, As a result of these findings I had the Factory
Kohler fuel filter replaced, added a second
heavy-duty filter, and a siphon break. Kohler and TAW
refused to cover these repairs although the
installation repairs had been performed by the Kohler Certified shops and Techs they had
specified. Kohler and TAW maintained that although
they dictate the shops and techs that may install and
repair the generator to maintain the warranty, they
take no responsibility for the work these shops
The generator has again ingested water. This time water was found in the oil and in the
cylinders. Kohler and TAW stated that they will
not look into the cause of the water entry to determine if
they will cover it. In addition, they have taken
the position that the water ingestion has voided
my remaining warranty and no future repairs of any
kind will be covered regardless of the cause.
Upon investigation of this issue I find that my
case is not isolated. Another boater in our
marina has recently experience the identical situation.
In both cases our generators were running
under load with no problems. Less than 24 hours
later the boats having never left the slip, the
generators had hydro locked and would not crank. In
his case Kohler and TAW have taken the same
position, they would not look into the cause and the
water ingestion has voided any remaining
I am now trying to get whatever life I can out
of the Gen Set before I have to replace it. I have
removed the water begun repairs. In my search
for parts I found several repair shops listed as
Kohler certified shops that had also experienced problems.
One simply suggested I replace the Kohler system
with another brand, stating he would never put a
Kohler on his boat; another stated that due to problems
he no longer carried Kohler products.
One shop went as far as responding to my inquiry
by sending the following e-mail response:
"If everything you describe is correct, then the
unit is installed correctly. The problem is
probably in the genset. One of the reasons we dropped
the line in the late 90s was they were having
some problems with the small gas units and not telling
the dealers about it. (I had to find out from
my Westerbeke rep.) After being threatened by
several customers of lawsuits due to their units not
being operational and the Kohler rep telling me to
let them sue, I decided I didn't need to be in
that picture anymore."
Kohler's attitude expressed above, let them sue, is
exactly what several others I've spoken
with and I have experienced.
An offer was made to replace my engine, labor at my expense,
with an engine having more hours on
it than my existing engine. They would provide no explanation
as to why it had been removed from
another generator, nor warranty. In an earlier conversation
I had asked them to cover a $200
invoice from a repair shop and they refused. I suspect
the fact that they offered this engine, but
refused to pay the $200 invoice is a true
reflection of the engines value.
I was recently on a weekend outing, 4 boats with Kohler
gen sets, by Sunday morning none of the 4
were running, 100% failure rate.
I was recently looking into a boat for sale at a nearby
marina, again more stories of problems.
The current owner stated that he has had problems
with the generator and kohler has not been
I have found that Kohler Power Systems is neither
willing to back up their product, or take
responsibility for the certified shops and techs
they dictate must be used to maintain the warranty.
From Norm on The Live-Aboard List:
The Panda is the quietest because they have the unit TOTALLY enclosed in a
sound box. But they run seawater through the aluminum generator end to do it.
The guys at the booth at Annapolis say it's all right, it will take a long
time for the aluminum to corrode. I don't believe them. The corrosion will form
a crusty heat-insulating barrier between the aluminum and the water and
eventually plug up the passages. If they had used a heat exchanger they might have
I have a Northern Lights 8 KW which engine and generator are made in Japan.
Alaska Diesel likes to brag a lot about their gear. Don't believe them. It is
a good rig but needs work before it is satisfactory, such as: engine-side
stop/start controls, output breaker, local outlets, engine-side oil pressure and
temperature gauges, 120 deg shutdown "clixon" switch on rubber exhaust hose
(available at HVAC store, it has saved me from replacing that hose a dozen times),
shield (I use duct tape, but a stainless shroud would be nice) around seawater
pump shaft area to prevent spraying seawater into alternator when pump seal
fails, strainer on hose output of seawater pump (I used a little plastic one
designed to protect the potable water pump) to catch rubber bits, indicating
breakdown of impeller and to prevent fouling of heat exchanger, etc., and in my case
at least, installation of pre-start lube oil pump. It would also be a good
idea to junk the $165 toy alternator that comes with the machine and replace it
with a run-of-the-mill $45 Delco. You would have to make a new bracket but
you will get twice the output at a quarter of the cost and ready availability.
Another thing, the cast iron exhaust elbow rotted out after a few years. I
had to make a stainless one. Get a stainless one right away while it is easy to
install. There is something that rattles inside the generator end when I shut
the machine down sometimes. I don't have a clue and neither does my dealer.
So far, the machine runs OK, but it does make me a little uncomfortable.
While some folks have had good
experiences with Onan, most have not. They seem prone to breakdowns, especially when
not run often, and the parts are extremely expensive.
While a genset is great to make lots to electricity, I recommend against
relying on it for basic needs. There are some boats that are totally electric,
electric galleys, heads, hot water, ventilation, windlass, etc. When the genset
goes down, and it will sooner or later, the boat is unlivable.
From article by Ed Sherman in 10/2002 issue of Cruising World magazine:
Diesel gensets ranging from 5 to 6 KW, list prices
range from $5K to $11K.
Portable gas generator:
- Genset is mandatory if you want air-conditioning.
- 8 KW models cost $10k+ in 1999.
- See 8 KW genset reviews in
Practical Sailor's 1999 Gear-Buying Guide.
- SeaPower engine-driven generator.
- Diesel-powered gensets are very expensive.
- If there are other boats nearby, and your genset is loud,
run the genset during
the daylight hours only, to avoid disturbing others.
- Run genset under load for at least 1 hour (best if continuous) per week.
Running it under very low load is bad.
From Jim McCorison on Latitudes and Attitudes Cruisers Forum
I would strongly recommend against a portable gas generator on a boat.
Yes, I know people use them. But friends of ours almost got killed by one.
They kept it in the aft lazerette and when they used it they ran a
flexible duct hose for the exhaust up and overboard leaving the
lazerette cover open. Later in the evening the wind blew it closed
pinching off the exhaust hose. Fortunately they couldn't figure out
why their 8 year old granddaughter was acting drunk and went
to investigate. Two people ok after a few hours in the hospital,
the other was ok after a 24 hour stay in an oxygen tent.
The other major problem is that if you have diesels you probably
aren't in the habit, or aren't equipped, to run bilge blowers.
Therfore it shouldn't be kept or run below decks.
Of course you could always run it up on deck. But the damn
things are so loud you'll probably have half the anchorage
offering to perform a buoyancy test on it.
If you really need a generator it is best to bite the bullet
and get a proper marine one with a proper installation.
The alternative could wind up being far more expensive than you planned.
From Bob Bitchin on Latitudes and Attitudes Cruisers Forum
... I always carry a small gas (usually a Honda) backup generator.
I assume I will be smart enough to run it on deck, in the open,
and won't suck on the exhaust pipe (except for an occasional high!).
I have an 8KW Fischer-Panda diesel generator installed belowdecks,
and I love the damn thing. Quiet, vibration free, but it cost a
little more than the "standard" Northern Lights or Onan.
Why? Because it is a new technology. I don't want to bore you
with technical sh*t, but basicly, instead of having mass quantities
of heavy copper wire spinning around, it uses a small stator, and
the electrical end is water-cooled, cutting down vibration and heat.
It only comes with a sound shield (not as an option) and, since it
is water-cooled completely, it doesn't overheat, as others tend
to do when enclosed. As for the price, I gotta be honest.
I don't know. They advertise with me and gave me a hell of a discount.
However, in all fairness, so do the other manufacturers, so I could
have chosen any one of them (as can you). I think it runs about $10-11 grand.
Something to keep in mind when choosing a generator.
If it's your primary, buy one that uses the same fuel as your engine.
Diesel is best. Be sure you calculate all your needs (i.e. water heater,
charger, vacuum, toaster, air conditioning (hey, it could happen!)
and watermaker). Choose one that will fit the area that you will
be installing it. If you are going cruising, ask the factory
for a "spares kit" and be sure to take it with you.
From Greg the Great on Latitudes and Attitudes Cruisers Forum
A lot of people carry a small backup generator not for
running all night, but to use as a backup battery
charger or for electric tools.
From Ed Kelly on The Live-Aboard List
I would forget about any contractor-grade generators or the cheap noisy ones.
Your reference to the Honda generators is on the right track if you
are interested in a portable that is quiet. They have 3 portable
models that are certified as computer-friendly, as they filter
through an inverter and have very low decible ratings. 67 dB which
you quote must be another commercial unit and is not nearly as quiet
as the portables I am referring to. (67 is just below the threshold
of a vacuum cleaner which is around 70 dB).
I have considered them, only because they can be used on the hard and
are so portable. I can forsee emergencies where one could be handy.
The three rated as having smooth sine waves and being computer friendly are:
EU1000iA2 1000 Watt max (900 W rated) 59 dB at full rated load - 30 lbs $780
EU2000i 2000 Watts (1600 W rated) 59 dB at full rated load - 48 lbs $1000
EU3000is 3000 Watt (2800 W rated) 58 dB at full rated load - 134 lbs $?
(per our Northern Hydraulics store)
They can each be cabled together with a combiner to double their output.
Downside is the fact they use gasoline (but are very portable in a small unit).
The output in the DC side on both is 12V, 96W (8A), but their AC is a
From Troels Kirk on The Live-Aboard List
We've owned a Honda Eu100 1000W for a year and a half. Size and weight is
perfect for our smallish catamaran. It's mainly used for supplementing the
solar panels when coping with grey/wintery skies.
It has proven to be totally reliable, relatively quiet at it's lower speed,
and easy to maintain. If stored inside, it's easy to empty the tank, and
there's a smart way provided to empty the carburetor as well. When on low
power (under 500 W or so) it seems to run forever on a couple of liters of
From Bob Austin on BoaterEd
> I have heard great things about Honda's EU2000
> but see that the price is listed at over $1,000.
> Today at Home Depot I saw a Coleman 1,850 watt
> generator for $399. Is there really that much of
> a difference between Honda and the other generators?
There is a world of difference and the Honda is definitely worth the cost. The Honda is many
magnitudes quieter and with less vibration. The components will last much longer (I have a smaller
Honda which is 30 years old and still runs fine). The Honda is an alternator inveter which will
synchronize with other Hondas, so that if necessary you can put two EU 2000's or with a 3000 or
1000 for more power. The Honda is lighter.
Do not anchor in a cove where I am with the Coleman!
From Flying Pig on list from liveaboardnow.org:
... my on-air seminar on the Honda eu2000i generators so
popular among cruisers, but bedeviled by what I can only assume is a
make-standard-parts-fit-non-standard-applications policy at Honda which has
nearly every 2000 eventually break their starter pull-cord due to a non-fair
exit in the rewind mechanism. Fixing that (well, making do on a relatively
permanent basis - there's no fix without boring into the crankcase and
relocating the mounting bolts) is very simple, but getting to the part
isn't! As I'd done a great deal of phoning around to distributors, I
eventually was able to find a service company who had a tech willing to walk
me through the procedure, which I shared. It's tedious, but not difficult.
That on-air session also included many tweaks I'd learned from the Honda2000
mailing list on yahoogroups (go to groups.yahoo.com and search for
Honda2000). Fortunately for those who came last year and took notes, even
though they'd not yet had the problem, they (as several ashore had told me)
were able to repair their broken cords successfully.
[S/V Freedom's "Replacing a Starting Cord in the Honda 2000i Generator"
Someone suggested putting the gas genset in the dinghy and running it there, with
the AC cable coming onto the boat and plugging into the shore power connector.
That way, noise, vibration and exhaust are off the boat. Of course, an AC power cord
over water is not a happy thing, a fire would kill both generator and
and a big wake could cause a problem.
From Laurie on Cruising World message board:
Don't buy an AC generator. Get a diesel driven alternator and inverter.
It's much more efficient to charge batteries with an alternator and use an inverter,
than to have half of your A/C KW rating just rattling around doing nothing (or being
50% efficient running a charger).
More from Laurie on Cruising World message board 12/2000:
Ample makes a 150 amp alternators driven by small Kubota diesels.
IMO they're the best on the market and go for about $4,000. With a thousand watt
inverter and installation you're looking close to $6,000.
But it's the best way to go by far. You'll be glad you did for more reasons
than I can explain right now. ...
I can sell you one at a great deal.
... DC generation has always been much better for battery charging, and inverters
now can easily handle any large load. Couple this with a larger battery bank and you
get the easiest to manage power utility that you can operate.
When you expect high loads, run the alternator gen-set. It will carry the entire
inverter load, then shunt all extra amps into the batteries. When the inverter load drops,
the alternator stays running, but more amps go to batteries. Very efficient.
When you expect light loads or value silence just use the batteries.
The clincher here is convenience. Once you live with the system you would see it's
much easier to run than adding an entire new power generation scheme into your utility,
with complicated switching for startup use, relying on separate AC chargers/regulators
for battery charging, etc.
Inverters give their full-rated power whenever you need it instantly and
silently -- with much more ready at the flick of a switch by starting the
diesel alternator. And by upgrading batteries, you'll get more efficiency
and more generator "off time" with AC still available.
IMO Ample Power has got the best diesel driven alternators on the market.
You can get a macho 180 amp alternator matched to a Kubota diesel with
a high performance regulator for about $4,000. Better yet, each component
is feasibly field replaceable (not so with many ac gensets), so if you
have trouble Ample can send new regulator, or a new alternator (and the Kubota is reliable).
Basically, it's a three-component plug and play system that's easy to
service with spare parts that are easily stocked (like a spare alternator
that fits both the boat and the DC genset).
I was so impressed with the numbers and Ample Power's experience on this I became a dealer. ...
From Matt on Cruising World message board:
Check out the Balmar
Interesting combo with the 250 amp DC alternator,
3000 watt inverter, water maker and dive compressor unit, a lot of bang for the buck.
From Norm on The Live-Aboard List:
I have a Northern Lights genset. Some things I did to it when I
From John / Truelove on The Live-Aboard List:
Local pushbuttons to prime, start, and stop the unit from engine-side.
Local oil pressure and temperature gauges on the engine.
An ammeter to check on the starting battery charging alternator.
A freq meter to adjust the governor.
An engine hour meter to know when to change the oil (a MUST!).
Circuit Breaker on the output line. There were already circuit breakers on
the field and 12 VDC circuits.
120 and 240 vac outlets on the unit itself so I could have power even if the
ship's distribution system was compromised.
The above electrical items were all mounted on the control box that houses
the control relays and voltage regulator.
A 120 deg F, Klixon, normally open thermoswitch (available at Grainger) on
the exhaust hose (held on with a spring around the hose) wired to shut down
the unit if the hose gets hot above 120 deg F (indicating a seawater flow
failure). The engine block will not get hot enough fast enough to shut down
the unit before damage to the exhaust hose happens if seawater is suddenly
cut off as by a plastic bag, etc. This has saved me several times.
A pre-start lube oil pressure pump to pump up the lube oil pressure in the
engine when you press the "prime" button. This is a 12 VDC gear pump I
bought from Depco. "They say" 80% of the wear happens in the first few
seconds of operation due to dry bearings.
A ball valve and piping to drain the oil easily for oil changes (every 200
A compound fuel pressure gauge downstream of the secondary (engine mounted)
filter to tell how plugged the secondary filter is.
I would like to have:
The oil filter to screw "up" instead of "sideways" so the oil wouldn't make
such a mess when I change the filter.
A little funnel and tube to carry away to the bilge the seawater leakage from
the mechanical seal on the seawater pump. These seals, on the main engine
too, always seem to leak somewhat. Even when I replace them, sooner or later
they leak again, but small leaks. Until they get substantial, I prefer to
let them leak but carry the drippings away with a funnel and tube to keep the
nearby metal from rusting.
As for your relay. This is common in stand-by power systems ashore and is
called a "transfer relay" to transfer the load from the mains to the
generator. Personally, except for protective devices, I shy away from
automatic things in general because I want to be fully aware of what is going
on. I have is a rotary manual transfer switch with "shore power", "25 KW",
"8 KW", and "grounded" positions. Before I move the switch I strip all loads
via the circuit breaker panel. This protects the transfer switch from arcing
and also starts the new power source with no loads. I then re-apply the
Another consideration comes into play if you have an inverter. My Trace
synchronizes itself to the external power source when one is available and
actually aids the external source for short heavy loads such as motor
starting. I quote:
"External Transfer Relays"
It is not acceptable to switch the AC input from one AC source to another
while the inverter is connected. This applies whether the inverter is in
battery charging mode or inverter mode. Switching the AC input from one
source to another can result in a loss of synchronization that can cause a
severe overcurrent condition that is far worse than short circuiting the
inverter. Two separate AC inputs are provided to eliminate the need for use
of external transfer relays. If a transfer relay is used, it must provide a
center "off" position that causes a loss of input power to the inverter for a
period of at least 100 milliseconds. This will allow the inverter to
disconnect from the original AC input and then re-synchronize to the new AC
source even thought the same AC input terminal is being used. During the
transition period, the inverter will have to operate the load while it
re-synchronizes to the new AC source (about a thirty-second period at the
minimum). Most transfer relays will switch too fast for the inverter to
detect - and will cause the inverter to lose synchronization with the AC
source. This is indicated by the inverter shutting down upon transfer and
the red overcurrent LED indicator flashing or turning on.
Manual, hand operated transfer switches may be acceptable since the transfer
time can be slow enough for the inverter to detect. The switch must go
through a center "off" position. They are often used to switch from one
generator to another. Since the inverter has a separate AC input for a
utility grid, a transfer switch is not required to switch from the utility
grid to a back-up generator. The inverter will not allow the generator to be
connected to the utility - if both are available, the generator will be
disconnected and the inverter will be connect to the utility on AC INPUT 1."
I cannot find it right now but I remember a passage in the manual that
cautions against connecting the output of the inverter to the AC mains. I
recall that it said the damage resulting from such a connection is "massive
and obvious and NOT covered under the warranty". I have a friend who did
just that twice and the damage was "massive and obvious and NOT covered under
> "They say" 80% of the wear happens in the first
> few seconds of operation due to dry bearings.
Yes, they do, and yes it does. But it isn't due to "dry bearings." It's due
to metal-to-metal contact between bearing surfaces before the hydrodynamic
"wedge" develops. The wedge is developed by virtue of the bearing surfaces
moving in relation to each other. It is not developed by pressurizing the
lubeoil system prior to start, and the same amount of wear will occur during
starting whether there is pressurized oil at the bearing journals or not.
Prelube pumps are a good idea on large engines which require a lot of time to
fill their oil distribution and filtration systems, and also on
infrequently-run engines such as those powering standby generators. They are
a waste of money on small, frequently-operated Diesels.
SailNet - Tom Wood's "110 Volts On Board"
SailNet - Don Casey's "Inverter Realities"
West Marine's "Selecting a Power Inverter"
Inverters articles in 5/2001 and 6/2001 issues of Southwinds magazine
Types of AC output:
- Square wave.
- True sine wave.
- Modified sine wave. (More like a square wave.)
Conversion to true sine wave is 5% to 10% less efficient
than conversion to modified sine wave.
Want true sine wave; modified sine wave affects some clocks
and radios and a few rechargable battery chargers, and
"contains harmonics that cause additional heating
in motors and transformers".
Laser printers require true sine wave power.
From BobG on Cruising World message board
Don't overlook the sine wave.
We made that mistake when we bought a 1500 watt inverter.
Later we discovered that so many electrical things require a full sine wave.
Anything that uses an electronic chip for timing requires a full sine wave.
IMHO the larger unit with full sine wave is a better choice, if you can afford it.
From Norm on The Live-Aboard List
The term "modified sine wave" is a salesman's lie. The output is a square
wave. Many loads don't mind, but some do and the output tends to be noisy
because of the abrupt changes in voltage.
The term "pure sine wave" is also a salesman's lie. The actual output is a
stepped waveform resembling a stepped pyramid. The number of steps depends
on the design and the load. That being said, the resemblance to a sine
wave is enough for almost all loads to act as if is were actually a sine wave.
As far as I know only a very expensive style of inverter will output a true
sine wave. Also a motor/generator set will. Both of these have poor
efficiency and are not useful to us.
From Arild on The Live-Aboard List
Norm is right about "modified sine wave":
MSW originally meant Modified Square Wave because the second generation had
a couple of steps in the square wave output.
About "pure sine wave":
We used an oscilloscope to compare the Trace and Statpower inverters.
The Trace SW2512 had 72 discernible steps in each cycle.
The high-frequency switch-mode designs from Statpower
had 4000 steps in each waveform.
We could not actually see individual steps but Engineering assured us that
based on the switching frequency there should be 4000. On the scope the
output looked as good as the pure sine wave coming from utility power.
From Pascal on BoaterEd
You don't need a true sine inverter for TVs. The only things which do not work (and burn up) on MSW
are tool chargers. Cell phone, MP3, computer chargers work just fine ...
Types of inverter construction:
- Line-frequency switching
(older; 4x heavier; hum and noise increase
as battery voltage declines).
- High-frequency switching
(newer; lighter; more complex; high-frequency
noise may affect SSB and weatherfax).
- Waveform type (square, modified-sine, pure sine).
- Idle current (current drawn from batteries when no AC load is applied).
- Efficiency (output power / input power; varies with load).
- Automatic transfer switch (detects presence/absence of shore power) ?
- Includes battery-charger ?
- Charging modes (sophistication of the battery-charging part).
- Controls and meters.
- Inverter must be kept dry and well-ventilated.
- Consider having two inverters: a large modified-sine for
most loads, and a small pure-sine for certain
- I don't like the idea of combined inverter/chargers:
makes a single point of failure that takes your whole system down.
See inverter reviews in
Practical Sailor's 1999 Gear-Buying Guide.
Statpower, Trace, Heart all made by Xantrex.
From Larry DeMers on The Live-Aboard List:
I installed a Heart Marine Combi 12-15 (1500 Inverter capability) this past
summer . Heart has some problems with EMI/RFI in their gear (all of their gear
that has an oscillator), and the charger/inverter is no exception. You may be
bothered by the 60 hz. growl radiated from the ac wiring in the boat. They do
have a fix for it ... at your expense, you need to add a Corcom filter to the AC
output lines, as it leaves the charger/inverter. This is a rather large device
that would be better suited to be installed inside the cabinet of the
charger/inverter in my opinion. It sure would make the AC wiring neater and
easier to route etc.
From Norm on The Live-Aboard List:
I have a Trace SW2512: 12 VDC, 2.5 KW, $2000, "sine wave" unit. Aside from
two warts (2 relay auto generator start instead of three, and volatile
parameters requiring reprogramming after a 12 VDC interruption) it is a fine unit.
Be aware that the manufacturers lie about the wave form of their outputs.
"Modified Sine Wave" is the more blatant lie. The output is in fact a square
wave with some off time between the pulses. Nothing remotely resembling a
The "Sine Wave" output claimed for my Trace is in fact a stepped waveshape
resembling a Mayan pyramid. The number of steps vary with the load.
The square wave output inverters are a bit more efficient than the stepped
wave inverters. However, the biggest effect on efficiency is the relative
size of the load.
For example, according to the graph in the manual my 2,500 watt Trace is the
most efficient (about 92%) at a load of 300 watts. At very low loads the
"overhead", or the power required just to run the machine, is a relatively
large percentage of the power draw so the efficiency approaches zero as the
load decreases. At higher loads "I squared R" losses gradually rise as the
current levels increase until efficiency is about 80% at 2,500 watts, maximum
rated continuous load.
From Arild Jensen on The Live-Aboard List:
Inverter manufacturers do know that "modified sine wave" inverters cause problems.
This is attested to by numerous customer complaints over the years.
However, customers, American customers in particular,
will almost always choose price over
quality. They percieve consumer products as disposable so what if it quits a little early.
Toss it and get another! Time for a style change anyways, or sentiments to that effect.
From Jim and Tom on The Live-Aboard List:
Induction motors run hotter and do not last as long.
Electronic controllers struggle with the
ramped-up voltage and soometimes fail as a result.
They tend to overheat or quit altogether with
what they perceive as voltage spikes.
A toaster doesn't care, so it works fine.
A DC drill (universal motors) doesn't care much
chops up the clean sine wave with its commutator.
But if you pay attention, you will find that a
Skilsaw or any other power tool does work faster,
smoother and with more power at part speed
range when run off pure sine compared to a MSW.
Switch-mode power supplies such as you see in many AC-powered electronic equipment like TV
and computers do not really care either since they make hash of the sine wave.
BUT!! ... the newer generation of universal power blocks, smart fast chargers and other
sophisticated products designed for a global market with varying voltages
and frequencies get
confused by MSW power. Result; pissed-off customers and sometimes burned equipment.
How do I know this? Because for two and a half years I was a marine applications engineer for
Xantrex during the corporate merger period when Statpower,
Trace and Heart got rolled into one.
After the merger a lot of notes wer compared amongst
the staff and all the sales bluff was swept
Even they realize that MSW is a dinosaur design and corporate plans are to eliminate all MSW
products in about two years when the next generation of pure sine wave products are slated to hit
They have already been all but shut out of the European market because MSW simply doesn't
meet current European EMI pollution standards. Companies like Mastervolt are grabbing market
share in all parts of the world becauss they already have more sine wave products and their few
remaining MSW products are better filtered and shielded.
As cruising folks who live off a battery away from shore power you should care about the
difference in sine wave vesus MSW.
Lab tests have demonstrated that the same equipment uses less power and thus runs longer on the
same battery charge when fed clean sine wave instead of MSW power.
These tests were done by the equipment manufacturers, not by Xantrex, by the way.
Audiophiles who enjoy clean sound also prefer the cleaner sound
in quality home entertainment
equipment when fed by pure sine.
Ham operators will attest to the amount of radiated hash in their equipment and SSB radios.
The downside of MSW is considerable.
We have run extensive tests of modified sine
wave vs pure sine wave inverters -- specifically
the Prosine. There is no question that the PURE
sine wave inverter is far superior. Just the interference
to radio on the SSB VHF frequencies generated by the
modified sine wave inverters is reason enough to go
with the pure sine wave version. Lab tests we have
conducted show a serious potential safety problem
with the modified sine wave. Don't take the chance!
From Arild Jensen on The Live-Aboard List:
It isn't just inverters that produce poor quality waveforms.
The new generation of small gensets have opted for a hybrid design in order to save weight.
Instead of having a massive iron core and copper-wound alternator, they employ a variety of
designs including a cheap two-pole generator which then feeds power into a solid state inverter.
Saving on copper and iron saves weight, reduces power requirements, and makes it easier to
vibration-mount the unit. But the trade-off is poor waveform control.
One of the drawbacks of some older designs was the voltage regulation. SCR controllers were
notorious for generating spikes. Although the frequency was fairly close, the voltage would sag as
the loading increased. Sometimes it sagged too much during a high-current start.
Cost is everything so many gensets designed for a price instead of quality, use cheap methods to
regulate and control their gensets. You the consumer, pay the eventual cost, but by then the
warranty has long expired, and hopefully no one realizes why appliances do not last as long.
It takes a sophisticated power-factor-corrected charger to make best use of such poor quality
power. Lacking a power-factor-corrected charger, your genset run time will be longer to charge
the battery up. A basic transformer-type charger will not do this. It takes the sophisticated
technology of switch-mode regulators to do this. The latest designs of inverters that produce
sine waves possess this technology. So not only do you get superior inverter power but in the case
of a combination inverter/charger you get faster, more efficient battery re-charging.
Manufacturers of the old traditional designs are dropping prices in order to clear inventories
cash in on what they perceive as the last chance to capitalize on this old technology.
The leaders have already switched over. The copycats and also-rans are lagging behind.
Without a solid engineering base to develop their own technology they have to wait for the next
wave of products to emerge before they can copy it.
The low price of the MSW products you see in the stores right now is a clear indication that
is the end of the line for the old technology.
From Maroth de Marothy on World-Cruising mailing list:
Microwave oven ... a WARNING: if you plan to buy a new one, make sure your inverter
puts out a pure sine wave, otherwise your new DIGITAL microwave won't work.
We found this out the hard way: When in Panama, we got rid of an old, non-digital
microwave and bought a nice new one. Worked fine under shore power but not with inverter.
This drove me nuts until someone explained the problem to me. Since I can't afford a new
inverter that would create pure sine wave, the microwave is only usable when in a
marina ... something we try to avoid!
From Phil Rosch on The Live-Aboard List:
[Heart Freedom] Inverter Gremlins:
It's another 90-degree day at Block Island and my Freedom 25 stopped
charging and inverting. Nightmare scenario? Not so, because I learned
(the hard way) the magic secret about these inverters and I'm going to
1. If your symptoms include charger amps starting at 125, but then
dropping to zero and starting up again over and over ...
2. If the charger and/or inverter blink off at the control panel, then
resume a few seconds later ...
3. If the lights on the panel go out and stay out ...
The problem is your grounds. The may look tight, but they aren't. If
you have thumbscrews holding down your negative cables, float-test them
and replace them with nuts and lock washers. Clean the terminals and
cable ends until they shine, then bolt them down and hose them down with
At the first sign of any problems with your inverter, repeat this
There's one other measure you can take when faced with desperation, short
of float-testing the entire unit. If the inverter/charger is acting
strangely but doesn't have a foul smell or the look of the proverbial
"smoking gun", the problem may be the microprocessor equivalent of
One example is when the control panel indicates the charger can't make
up its mind what phase it is in. You might be sure you should be in the
bulk phase, but the charger drives up to 125 amps, then down to zero as
if it had finished the float phase. Doing this repeatedly at 3-4 minute
intervals is a sure sign of corrupt memory in the unit's "confuser".
Technical bulletin issue #19 says these "brain-farts" can be caused by
nearby lightning strikes, voltage surges from shore power or generators,
engine starter motor related spikes and dips, or high-voltage propane
The recommended "re-boot" procedure is to remove all A/C power (un-plug
and/or turn off the genset), disconnect the phone jack powering your
control panel from the unit, turn off the inverter power switch if you
have one, and then disconnect the negative battery terminal for a full 5
minutes. This will allow the micro-confuser to be "refreshed" at the
Reconnect the negative cable and expect a pretty good spark as the
filter capacitor charges up inside the unit, then plug in your control
panel, apply power to check the charger, and then remove it to check the
inverter function. If this works, pour yourself a "Dark and Stormy" and
From Arild Jensen on The Live-Aboard List:
Many Asian built-boats have the neutral white wire connected to multiple branch
I have found this out the hard way. By ringing out the individual circuits at
the main panel I discovered there are more black wires leaving that there are
white wires returning. The reason being that the electricians tied two or more
outlets together on a single common white wire.
This practice can produce more electrical noise and allow any spikes to cross
into multiple circuits.
While the old Heart models didn't seem to mind this too much, the new Prosine
shuts down every time.
The fault detection circuitry is too sophisticated and rejects the odd wiring
configuration as a fault.
Another practice which can contribute to electrical noise that causes
inverter memory problems, not to mention actual metering problems, has to do
with separating the neutrals for the input and output circuits.
When the whole boat is wired through the inverter there is no problem. The shore
power input line connects directly to the AC IN terminals. All the boats
electrical panel connects to the AC OUT terminal. However, it is not a good
idea to run high loads like water heaters, baseboard heaters and air
conditioning through the inverter since these drastically reduce battery run
For such installations you should run what is called a split bus. The high
draw equipment is wired to the main panel along with the inverter. The
remaining loads are fed from a separate bus that is connected only to the AC
OUT of the inverter. Many installers fail to separate the white neutrals as
well. They leave all the neutral wires connected on the same bus bar. This
forms a feedback loop where noise and voltage spikes can loop back to the input
where the inverter's sensing circuits can get confused.
If the boat has been wired with multiple circuits to a single white common
wire, the problems multiply.
Last week I came across a boat that had been upgraded from an old Heart
inverter to a new Prosine. All of the above conditions existed and naturally
the inverter kept shutting down and refusing to work. While the inverter
would usually work on shore power it flatly refused to work with the genset.
Careful investigation revealed that the genset had never been properly wired so
the white wire was bonded to the green wire.
The manufacturers do not necessarily tie the green and white wire together
since many applications in metal hulls require them to be kept separate.
Evidently the original installers failed to do this necessary step. The old
Heart model inverter was not sophisticated enough to detect the problem.
The new Prosine did and shut down. It was only a matter of luck that no one
ever received a shock from this poor wiring setup.
From Ben Okopnik on The Live-Aboard List:
My 2kW inverter cost less than $90 brand new (Whistler 2000, on sale at Harbor
Just for general info, I've owned Whistler inverters of all sorts over
the years, and for a dirt-cheap off-brand, I'm very impressed with them.
I've only ever had one blow out - at which point, I replaced the easily
accessible transistor and was powered up again within 20 minutes
(something you _won't_ be able to do on a number of the high-end units.)
The thing that I find really good about them is that they work *way*
beyond their rated capacity, especially the small ones. I had a 600W
unit on my previous boat, and it ran my little Shop-Vac vaccuum cleaner
just fine; I didn't realize how amazing this was until I tried using it
on several much larger inverters (up to twice that size), and none of
them could handle the startup load.
The only annoying thing about them is that you "pay" about 1A @ 12VDC in
standby current. I just shut mine off when I'm not using it.
West Marine's "Shore Power"
Steve Dashew's "AC Shore Power Adaptors"
120/240 shore power article in 10/1/2000 issue of Practical Sailor.
Two articles in 4/2003 issue of Cruising World magazine
From Loren Beach on Yacht-L mailing list:
This last winter we had a local surveyor give a presentation to our club
members. She brought in her box of blackened shorepower connectors and
blackened plugs as a sort of traveling horror show. We had heard this from
another surveyor before, as well. Evidently it is common for the plug to
work a little in the connector on the boat and finally start arcing over
as it moves with boat movements.
I have no trouble believing this as the shorepower inlet was one of the
things the surveyor found, in '94, when our '88 boat was surveyed for
purchase -- it was a little blackened around where the prongs went in. It
Definitely something to check on often any boat connected to shorepower --
just a teeny tiny bit of movement, a zillion times a day ...
From John Gill on Great-loop mailing list:
Make sure your power cord connections are clean and not worn, and inspect
the dock electric station receptacles when plugging in - some are
corroded and/or worn and in very bad shape. Put a can of electrical
contact cleaner and an old tooth brush in your tool kit to clean them.
If you can't make a good firm mechanical contact, think twice about
plugging in, because you will not have a good electrical contact either!
We also learned from other boaters to take a length of 3/8 inch line
about 6 feet long, make a knot around each of your power cords and then
tie the cords tight against the dockside power station. This prevents
accidental, vandalism or other removal of the power cord that is not
intentional. More than once, we had someone try to remove one of our
power cords in order to hook up theirs!
Ron Holmwall article about a boat fire
From Jeff Smith on The Live-Aboard List:
One of the most common causes of boat fires is the shore power inlet.
The connections are made with setscrews and over time they seem to loosen.
I really don't know why.
As they loosen, the resistance at the connections increases, resulting in
heat at the connection points. Left unchecked, a fire can result. This is
especially a problem for winter liveaboards who run electric heaters and
draw a lot of current.
From Lew Hodgett on the IRBS live-aboard mailing list:
[Re: Low voltage at marinas. Stimulated by a quote from ABYC:
From Nelson Bailey on the IRBS live-aboard mailing list:
"Marina dockside power systems may be causing problems on boats such as
overheating motors and reducing the life expectancy of appliances and
equipment. These problems can exist in spite of the latest and best
power outlets and oversized wiring on the piers. The problems are not
generally caused by the equipment on the boat or on the piers, but are
due to dock receptacles being supplied with 208 volts AC power instead
of 240 volts AC power."]
208Y/120/3Ph/4W/60Hz is a very efficient way of distributing 3 phase
power which then can be utilized as single phase power.
The "Y" above denotes a 3 phase transformer connected in a "Y"
The 4W above describes 4 wires as follows:
Phase "A", Phase "B", Phase
"C", and "N" for neutral.
The voltage between any phase and neutral such as A-N is 120V/1Ph/60Hz.
The voltage between any two phases such as A-B is 208V/1Ph/60Hz.
There is no inherent phase unbalance in the above.
The problem occurs when 208V/1Ph/60Hz is used to attempt to start a
240V/1Ph/60Hz load such as an induction motor.
If you find yourself is such a situation, usually the only solution is
the installation of a buck-boost transformer.
NEMA defines very specific plug and receptacle configurations for both
208V and 240V services.
If the installing contractor installs the wrong receptacles or the wrong
receptacles have been specified by the system designer, that's not the
problem of the distribution system.
The basic reason to use 208Y/120/3Ph/4W/60Hz distribution rather than
120/240V/1Ph/3W/60Hz is economics.
You need a lot less equipment and it is easier to balance system loading
using the 208Y/120/3Ph/4W/60Hz approach.
My suggestion would be that if you have shore power installed on your
boat, even if it is only a 120V/1Ph/60Hz system, include a voltmeter in
your tool kit, and use it before plugging into any shore power receptacle.
Lew, You are dead on with the exception of the transformer being the only
solution. This is a very common problem that I have found in commercial
buildings that are wired with 3 phase and then had equipment installed that
was wired for 240V. A large percentage of motors (such as
airconditioning/refrigeration compressors) rated for 240V are also rated
for 208V. It usually states on the rating plate "240/208V". It is a very
simple matter of changing jumpers or connecting to a different pigtail in
the endcap of the motor to change from one to the other. On a boat you just
have to remember to change it back when you move to a different marina.
- Voltage may go low during heavy demand (summer air-cond).
- Marina may tweak voltage up to keep it okay during
heavy demand, but this makes it too high during low demand.
- 3-phase 240 V and transformer may give single-phase 208 V
instead of single-phase 240 V.
- Best if shore power cable attaches to the boat inside the boat;
no on-deck receptacles ?
- Don't swim in marina near any boat connected to shore power;
any leakage could kill you.
- In small, third-world countries, lightning may cause large spikes in
the nationwide power grid and into your boat: the much larger USA grid
absorbs lightning strikes much better.