Running engine at anchor for hot water - load

[sailingharry]

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

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

We put in a 10 KW unit for our two trips to canada. Beyond awesome! The warm cabin is nice, but the endless hot water is even nicer.

[Letterkenny]

Originally Posted by Stu Jackson

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.

I have my house bank (which I am in the process of upgrading) and two large external batteries (600ah in total capacity for these two) that I use to run a portable air conditioner (for those that know, an EcoFlow Delta Pro and Extra Battery powering an EcoFlow Wave 2). What that means is that I can put about 1500-1600w into the EcoFlow batteries per hour on the Honda but that caps all the Honda can do and while I usually don’t drain the Delta Pro’s completely in a night, I still like to plan if that were to be the case. Charging the house bank then would be extra time running the generator then as I don’t have the overhead to charge them simultaneously. I can always put out all my solar panels but it equates to saving 1 hour run time which isn’t very efficient from a time or cost perspective. I am debating getting the EU 3200i (or adding a second EU2200I) as that would allow me to charge both banks/heat water at the same time and mean lower generator usage.

If it were cheap/easy enough, I would look into adding a generator (maybe a Fischer Panda) in the aft garage but unfortunately, that seems to be cost prohibitive.

Originally Posted by Jim Cate

Why is that so?

Jim

I’m assuming the poster is in the camp that all portable generators are bad and will kill you from carbon monoxide poisoning. There are many threads arguing back and forth on this.

[malbert73]

I think you’re overthinking it here. You’re lucky to have a relatively small engine (20hp) according to your first post. That means it’s going to be loaded up anytime you’re motoring. I don’t think you’ll hurt it at all for your occasional cruises especially if you combine bulk charging batteries and making hot water for showers. Yes it’ll be somewhat lightly loaded but you can balance that by using it to motor occasionally. I think I read this is for occasional cruises not full time cruising? In which case use what you have. You’ll get 4-8K hours out of that engine regardless

[Letterkenny]

Originally Posted by malbert73

I think you’re overthinking it here. You’re lucky to have a relatively small engine (20hp) according to your first post. That means it’s going to be loaded up anytime you’re motoring. I don’t think you’ll hurt it at all for your occasional cruises especially if you combine bulk charging batteries and making hot water for showers. Yes it’ll be somewhat lightly loaded but you can balance that by using it to motor occasionally. I think I read this is for occasional cruises not full time cruising? In which case use what you have. You’ll get 4-8K hours out of that engine regardless

You got it. Realistically I doubt I’ll get to 4K hours before I sell the boat and yes, for occasional use (6-8 trips a year).

[Cheechako]

Originally Posted by Letterkenny

I have read some threads here on this and know of the general note that running a diesel not under load is bad for it. I have a Yanmar 3YM20 and am looking to do some longer trips on it. It seems much more efficient to run the main for heating water and also helping add power to the house bank than using the water heater connected to a Honda generator. My concern is the lack of load (this will be pushing the button on the throttle to enable a higher RPM while still in neutral gear). What are the main concerns or considerations to have here? Is it potentially putting it in reverse at anchor or on a mooring ball to add load while the engine heats up/charges the batteries?

This is what I have always done while cruising. Also: The engine does have a load on it, the alternator. With a small engine like yours it's even less of a risk as the alternator loads the engine enough to hear it lug down with a big alternator.
As far as anything I can tell, the lightly loaded engine is a very minimal risk, if any at all really. 18 wheelers idle for hours. I have engine charged my various boats for 40 years, never had solar, although I had two wind gens for additional charging on two boats. They came with the boats.
Most of the time I found hot water in 20 minutes of running.

[sailorboy1]

For me the best way to heat water by running the engine at anchor is to turn on the inverter and heat the water that way. My alternator can do about 70% of the heater power so I may or may not need to run it more than about 20 minutes if the water is cold at start. But I know from experience that 20 minutes is enough time to made water warm enough for 2 shower.

I had to rewire my emectric panel to be able to do this.

[Stu Jackson]

Originally Posted by sailorboy1

For me the best way to heat water by running the engine at anchor is to turn on the inverter and heat the water that way. My alternator can do about 70% of the heater power so I may or may not need to run it more than about 20 minutes if the water is cold at start. But I know from experience that 20 minutes is enough time to made water warm enough for 2 shower.

I had to rewire my emectric panel to be able to do this.

Dang, I plumb forgot about that one! Thx SB. Some health issues have reduced my boat use in the past 2 years, but I did this often back in SF.

[rwidman]

Originally Posted by Jim Cate

Why is that so?

Jim

You have been around enough to know why that is so. I am not going to take your bait.

[Jim Cate]

Originally Posted by rwidman

You have been around enough to know why that is so. I am not going to take your bait.

It's true... I have been around a long time, but I'm not sure what danger you envision in running the portable gen set. Is it CO? Electrical hazard? Gasoline on board?

For those who have not been around long, explaining your blanket statement might help them understand the hazard(s) and do something to alleviate them.
There are certainly lots of folks running such gen sets on their boats...

Jim

[GILow]

Originally Posted by Don C L

I’ve probably been on a little boat too long but using combustible fuel to generate electricity to heat water for a shower seems a bit Rube Goldberg to me. Given the set-up, the generator makes sense. But a solar heater or even a kettle on the stove makes more even sense, but that’s just me.

Exactly. And a bit unfair on Rube because there’s usually at least SOME sense in the average RG machine.

Diesel heater for the water at the very least.

[Don C L]

Originally Posted by GILow

And a bit unfair on Rube because there’s usually at least SOME sense in the average RG machine.

[Bill_Giles]

Solar panels for warm water and battery charging is more sensible.

[Shaneesprit]

If you run it for 30 minutes every now and then it will be ok - If you also move the boat via engine power every now and then.
Raising the revs may help but not a lot. Combustion Temperature is all important - not coolant temp.

Downsides to running at little load
1) more hours on primary engine.
2) carbon buildup in the cylinder heads
3) Carbon build up at exhaust elbow - leading to restricted exhaust and power loss -
4) exhaust carbon build can cause a fire - I have only ever seen it on machinery not a boat but still.
5) diesel in the oil
6) Engine runaway
7) Engine failure
In extreme cases

[izzyforreal]

Originally Posted by Don C L

I’ve probably been on a little boat too long but using combustible fuel to generate electricity to heat water for a shower seems a bit Rube Goldberg to me. Given the set-up, the generator makes sense. But a solar heater or even a kettle on the stove makes more even sense, but that’s just me.

Isn't a kettle on the stove using combustible fuel?

[dan104]

Guess I must be lucky, my boat although only 36' has a nice standup shower and a 6 gal water heater that uses both exhaust heat but also AC heater. I have found on passage any time we run the motor (Beta 43) we are making water, heating it, and topping up batteries. One thing to worry about at idle speed is that if you are charging LiPo4 batteries they will draw more power that the fan on the alternator can cool for it's needs and it can over heat and burn.


BTW: Coming back from Islands to Chesapeake we had 4 on board and every body took hot showers each day, of course we used 60g for a 1600NM trip.