Running engine at anchor for hot water - load

[wsmurdoch]

When at anchor we run our Yanmar 3HM35F daily for an hour or so to cool the fridge/freezer (engine driven Sanden HD5H14 S6664 compressor), charge the battery (100 amp GM CS130D alternator), and heat water. In cold weather we also heat the boat with a bus heater that is in series with the water heater. The engine heats up quickly although I don't know the time. We have over 12,000 hr on the engine with a rebuild back at about 6000 hr due to high oil usage caused by corrosion of the steel rings in the aftmost cylinder's aluminum piston. Our oil pressure now falls off from 40 psi to 20 psi when the engine reaches operating temperature. But, it starts on the first turn down to 32F. does not smoke at all, and uses less than a quart of oil per 100 hr which is the oil change interval.

If your engine is slow to heat up, you might try replacing the thermostat.

[s/v Jedi]

I have a an Isotherm 40 liter water heater with 750W element. Running that for 15 minutes gives me hot water while the Honda EU2200 will still have another kW available for battery charging.

[malbert73]

Originally Posted by TrentePieds

Ah yes -)! Never go the simple way (read "five bob kettle on the hob") when you can go the "technological" way (read $30K Diesel Engine) to do the same pedestrian job :-0!

Even in a "huge" 34 footer, there really isn't room to have a shower below decks. doing so just gets water everywhere, which takes hours and hours to clean up adequately.

TrentePieds

TP- What do YOU do when you shower that takes hours and hours to clean up??🤣

To the OP- I think either option is fine but please don’t run the Honda near other boats under load. I try to escape the sound of lawnmowers when I’m at anchor. And I think a conventional running water hot shower is so nice at the end of the day - probably just after refrigeration on luxuries I couldn’t do without

[Don C L]

It is possible to get a nice hot shower without a diesel engine or electric water heater, even on a cloudy day. I think there is an old thread on that from long ago. It may not be one where you luxuriate under 5 or 10 gallons of steaming hot water though!

[Letterkenny]

Originally Posted by malbert73

TP- What do YOU do when you shower that takes hours and hours to clean up??🤣

To the OP- I think either option is fine but please don’t run the Honda near other boats under load. I try to escape the sound of lawnmowers when I’m at anchor. And I think a conventional running water hot shower is so nice at the end of the day - probably just after refrigeration on luxuries I couldn’t do without

Well that’s one of the reasons for wanting to use the internal diesel. Seems that many are going down the path to make these “hybrid generators” which is likely too expensive to set up. I’m unlike the norm here and don’t like to go without the luxuries if I don’t have to when on my boat. I want my boat to be my happy place and enjoyable (just need to figure out a solution to my berth problem now). That causes me to use a lot of power. I have many removable solar panels I can use and place throughout but at the end of the day, I will require a lot of generator usage to get things charged up. I think the only way to potentially decrease the amount of generator usage is to get a bigger generator so I can charge my house bank and my external batteries at the same time and near their max load. At the end of the day, all the solar I could put up on the boat would maybe save an hour run time.

[Letterkenny]

Originally Posted by TrentePieds

Even in a "huge" 34 footer, there really isn't room to have a shower below decks. doing so just gets water everywhere, which takes hours and hours to clean up adequately.

Well my boat has a large separate shower that my wife likes more than our home showers. I haven’t done many longer trips yet and that is what I am looking to do. On all my one nighters, I have actually always had hot water from having the water heater on at the dock and then any residuals from motoring or having to start the engine to drop the hook (not sure what does it) for a quick shower. Just want to see options for a week long trip and what that would mean.

[CaptTom]

Originally Posted by Letterkenny

I already have an EU2200i so I guess I’ll use that. Perhaps I’ll look at getting the new EU3200i as my main concern is trying to run it less in the day between the two different banks that I have to run and don’t always want a generator running.

I'd suggest you wait on that. You might find the 2K is plenty.

Originally Posted by Letterkenny

Just want to see options for a week long trip and what that would mean.

If you're motoring more than an hour or two per day, there's a good chance you'll have enough hot water for washing the supper dishes and taking a shower in the morning.

If you're at anchor for days on end, you may find you need to run the generator for about an hour in the late morning and/or early evening. (Respecting "quiet time" for others in the anchorage, of course.)

Do the math. What is maximum current draw of your battery charger and water heater? You'll want to size the generator to support those two loads concurrently. With FLA batteries, note that you will probably never quite hit the maximum charging current, and even if you do it'll drop off pretty quickly. So if you're close to the capacity of your generator, you may find it easier to just start the charger a while before the water heater, and save the expense of a larger generator.

Again only talking FLA batteries, also consider that you don't want to run your generator until the batteries are at 100%. That'll take many hours. I shoot for charging from 60% to 80% if I'm away on the hook for days.

Newer Lithium-based battery chemistries will have different charging profiles, but either way you probably only need one or two hours per day charging (and water heating) time.

[Letterkenny]

Originally Posted by CaptTom

I'd suggest you wait on that. You might find the 2K is plenty.



If you're motoring more than an hour or two per day, there's a good chance you'll have enough hot water for washing the supper dishes and taking a shower in the morning.

If you're at anchor for days on end, you may find you need to run the generator for about an hour in the late morning and/or early evening. (Respecting "quiet time" for others in the anchorage, of course.)

Do the math. What is maximum current draw of your battery charger and water heater? You'll want to size the generator to support those two loads concurrently. With FLA batteries, note that you will probably never quite hit the maximum charging current, and even if you do it'll drop off pretty quickly. So if you're close to the capacity of your generator, you may find it easier to just start the charger a while before the water heater, and save the expense of a larger generator.

Again only talking FLA batteries, also consider that you don't want to run your generator until the batteries are at 100%. That'll take many hours. I shoot for charging from 60% to 80% if I'm away on the hook for days.

Newer Lithium-based battery chemistries will have different charging profiles, but either way you probably only need one or two hours per day charging (and water heating) time.

I use a lot of power so will be more time than that unfortunately. I also have two banks which is the only reason going up a size in generator may make sense to reduce run time.

[Stu Jackson]

Originally Posted by Letterkenny

I use a lot of power so will be more time than that unfortunately. I also have two banks which is the only reason going up a size in generator may make sense to reduce run time.

Two separate house banks? If so, why?
A house bank and a start battery? No problem,, charge them both with the alternator when motoring, the start bank could do 60 starts between recharges and usually needs very little to top off.
Basic stuff. Load daily is daily load, regardless of how many banks you have. Recharge is charger capacity, battery acceptance vs time.

[The Yacht Rigger]

On my cat I run 185a (28V) alternators, so while making hot water (if needed, solar does it most of the time) I can add significant AH to my battery bank.
Best of both worlds, it's like running a massive generator, but it heats water as a byproduct.

[Flod]

I am considering putting in a hydronic diesel heater. Would give you heated warm water in no time. Also much nicer heat when cold outside, and it also could preheat your engine to get rid of cold starts. These 5kw units are small (like 210mm times 90 mm) and cost about $1000

https://campingaffaren.se/products/v...QaAhP0EALw_wcB

[rwidman]

Running your boat's engine just to heat water is pretty inefficient. Running a portable generator to power an electric water heater is not safe.

We generally try to use hot water (for showers, etc.) while the water is still hot from the day's cruise.

[Stu Jackson]

Originally Posted by Flod

I am considering putting in a hydronic diesel heater. Would give you heated warm water in no time. Also much nicer heat when cold outside, and it also could preheat your engine to get rid of cold starts. These 5kw units are small (like 210mm times 90 mm) and cost about $1000

Yes it would. You need to study how to do it in conjunction with your heater and engine circulation. A friend of mine did it with valves so either the water heater or the boat heaters got it but not both, although I'm sure it could be done other ways. He felt either the water heater could wait or the cabin could.

[Jim Cate]

Running a portable generator to power an electric water heater is not safe.

Why is that so?

Jim

[Jeff F]

I'd suggest adding a high capacity alternator, something that can put out 150 amps+. That turns your 15kw engine into a 2kw generator. 15% of rated load is enough to get up to temp fairly quickly and not harm the engine.

Then you have fast charging and hot water.