Generator or Inverter for a small cruiser?

G

GregR

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I have owned many boats and with the exception of the first two always had a generator. I can count on one hand the number of times I have used a generator for an extended period of time, to run the AC for example. Even then, never overnight. Too much risk for me.

I mostly use it to run the microwave, run an appliance, charge a phone, etc. I start it, run it for 10 minutes, then shut it down, or let it run with a load because it needs to run. I am more of a take a trip to a marina type then I am an overnight anchor type. So I almost always have shore power to hook up to.

I found a boat I really like, and I have literally found two, one year apart, in almost identical condition and you got it, one has a genny, one does not. The one without the genny is $10k less. It also has outdrives, which I prefer. The genny boat has inboards.

I've been doing research on inverters and this looks like a good short term, on demand AC power solution, compared to a genny. Literally, on the last boat I had I ran the genny, simply to run it because the genny mechanic told me to (which I understand why).

For those who have looked into an inverter versus a genny option, and maybe even went with an inverter, what are your thoughts?
 
For $10k less, I'd say go for the one without a generator. You can always add one. Adding an inverter with a bank of oversized batteries is also an option, again less than $10k. The inboard vs the outdrive would be the bigger question for me. I've had both and have run aground on Great South Bay and Moriches Bay with both. I find handing a twin inboard much easier than handling a single outdrive. I also don't have to contend with replacing bellows and worrying about pulling the outdrive and storing it in the off-season. Then again, I now have a 33' foot boat compared to the 24' and smaller boats I had before. Oh, I also boat on the Sound rather than the south shore waters. Best of luck whatever you choose. Hy
 
My personal preference is to use the "big battery bank + inverter" solution whenever possible.

That said, you really need to put pencil to parer to make the decision.

First you need to know just exactly how much "juice" you need. A Mr. Coffee is a 850w device, but if you use it to make a pot of coffee, then shut it down, your total consumed will be ( in the range of ) 140 watts consumed. ( You really need to look at all of the consumption and plug through the math. When you do, assume that a 12v 100A battery will store and provide 500 to 700 watts per full charge cycle. That covers most of the efficiency and "proper usage" caveats )

Similar numbers apply to a microwave oven; A 1000 W oven, used for a short time will use considerably less than the "1000 watts". But is you decide to cook rice for 20 min in the Micro, you will consume much of your stored capacity. ( 300+ watts )

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A "nice battery bank" such as a pair of 100A 12v, a 1 kW inverter ( or up to 2 kW ), plus a "1kw Honda portable generator" or equivalent, might be just exactly what you had in mind. It has the worst of both worlds, ( ie: a portable gasoline motor, plus the weight and storage issues of both systems ), but it still might be a good solution.

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I used a "2-battery house bank" and foound it satisfied all of my needs, but those were true "off grid" usage protocols. No A/C, no fridge. LED lighting, etc.

Really, only you know what you need or want, but if you do the actual number crunching, one of the solutions will "crush" the other two ( battery, bat + small genny, built in genny ).
 
Quite a bit of it all depends on the intended use of the boat. Gas gennies spin fast and are more of a nuisance but running the main engine with a high ampere alternator to charge a battery bank might be a solution. If the alternator can bulk charge the batteries and concurrently drive the inverter it could work but that implies a separate charger as opposed to an inverter charger combo. Many sail boats use the main to charge batteries. We heard them spinning early in the day at Hope Town Harbour all of the time.
 
Greg
How is the Boat powered? Gas or Diesel?
 
It's a 2004/2005 Cruisers Yachts 320, both have twin Volvo 5.7 GXi gas engines. Built in battery charger.

I've had twin v drives but really liked the twin outdrives in my last two boats. Performance felt better to me. Boat will be stored in a boatel.

V-drives with a genny equals no engine room compartment, which I am not a fan of.

I have already looked at the one with the genny, it shows very well. It's a fresh water boat. Plan to look at the one with the genny today. It's a salt water boat.

No genny - https://www.yachtworld.com/boats/2005/cruisers-yachts-320-express-3015407/?refSource=browse listing

genny - https://www.yachtworld.com/boats/2004/cruisers-yachts-320-express-3509324/?refSource=browse listing
 
My generator use is like yours. I'd opt for the one without. You can buy a lot of fuel and boat toys for 10 K. Have to disagree with Hy though, not likely to add a generator later for 10,000.
 
Asking prices are meaningless for comparison as you don’t know what the seller will accept. What would you decide if both were the same?
 
I would purchase the boat without the generator and “oversized” the house battery bank. Make sure the house batteries are isolated from your starter batteries and there is no risk. If they go dead just run the boat to charge them. Your use is similar to mine and a generator to me is not worth the additional cost of the boat, maintenance, or the extra weight on board. It’s about boat owner preference.
Jim
 
quote:
Originally posted by Gregory S

My generator use is like yours. I'd opt for the one without. You can buy a lot of fuel and boat toys for 10 K. Have to disagree with Hy though, not likely to add a generator later for 10,000.

Click to expand...


I contacted the gentleman who did a lot of generator repairs on my last boat, he said with the newer models it's about $15,000 plus to install a new generator.

"With the cost of the new generators it is expensive,it can run in the neighborhood of 15 to 16 thousand parts and labor to do a ground up install on that boat the generator alone is 10 to 11. the new units are electronic fuel injected with catalytic converters making them much safer but that has driven the cost very high"
 
quote:
Originally posted by pdecat

Asking prices are meaningless for comparison as you don’t know what the seller will accept. What would you decide if both were the same?

Click to expand...


I do understand your point, but I disagree. Boats are selling very close to asking price in this market. all else equal I would buy the boat with the generator, mostly for resale only though, not for personal use.
 
The devil is in the details like what brand generator, inventer and how big the battery bank

Some gas gensets are reliable, quiet 1800 rpm and produce low CO (Westerbeke). Others run at 3600 rpm and chew impellers and spark plugs on a monthly basis...

If you don’t need or don’t want to use air con away from the dock then don’t bother with a generator. An inverter will be fine as long as you have a good battery bank. I would now run an inverter off the typical small boat battery set up. I believe a deseicate battery bank for the inverter is a must.

But as always it depends on how you use the boat.
Years ago I installed a 3kw inverter in my boat with dedicated bank and cut genset time by 75%. Still ran it at night for air con except in cold winter nights

A low co gas genset properly installed along with CO detector is very safe.
 
Since you will rarely use the genny I dont think it is worth the cost and maintenance to you.
 
Looked at the 2004 with the Genny today. It's shows very well, very clean, but...the generator doesn't work. Seller never fixed it because he really never used it.

I do love hearing the engines on inboards idle compared to outdrives!
 
Less corrosion issues with inboards but since you are racking the boat it's a moot point.
 
quote:
Originally posted by PascalG

The devil is in the details like what brand generator, inventer and how big the battery bank

Some gas gensets are reliable, quiet 1800 rpm and produce low CO (Westerbeke). Others run at 3600 rpm and chew impellers and spark plugs on a monthly basis...

If you don’t need or don’t want to use air con away from the dock then don’t bother with a generator. An inverter will be fine as long as you have a good battery bank. I would now run an inverter off the typical small boat battery set up. I believe a deseicate battery bank for the inverter is a must.

But as always it depends on how you use the boat.
Years ago I installed a 3kw inverter in my boat with dedicated bank and cut genset time by 75%. Still ran it at night for air con except in cold winter nights

A low co gas genset properly installed along with CO detector is very safe.

Click to expand...


Thanks Pascal. I am leaning towards the inverter option with a dedicated battery bank, and going with the boat that does not have a genny. Especially now that I know the genny on the other one does not run. I'm sure it's just a carb rebuilt/and or fuel pump replacement repair.

Yes, I can make an offer contingent on a running generator, but then I am still paying for that running generator.

Can the inverter be wired into the current electrical outlets or panel, or would it be it's own, separate outlet(s)?
 
"Can the inverter be wired into the current electrical outlets or panel, or would it be it's own, separate outlet(s)?"

Either, actually. Just remember that your ( 1kW / 2k ) inverter is not ConEd... you have about "one household circuit" ( usually ) total available.

Much more important is to locate the inverter as close to the "house battery bank" as possible. At low voltage you are dealing with (very) large currents, which means very large ( and $$$ ) wiring. The shorter that run is, the cooler and more efficient your system will be. The higher voltage ( ie: 110 VAC ) can use a much more normal size wiring, so longer runs of that are practical.
 
Yes of course. Properly installed an inverter is set up to feed most of the panel (except AC, charger, stove and water heater) transferring power automatically and switching to charge when power is present
 
Greg

My boat has a second Alternator on the port engine to help out the House bank while under way, instead of running the gen.
If you go with the Inverter it's something to think about
 
Yes a good inverter can operate in "pass through mode". In other words, it will not drive the outlets while on shore power but can be programmed to detect a power requirement and drive the outlets etc.. When shore power is supplied it will (if active) detect shore power, line up get in phase, and back out leaving the boat on shore power. Some of the inverters can be programmed to detect different power level requirements before inverting.
 
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