I've always been of the impression that heat exchanger type
water heaters don;t work well with raw water cooled engines.
The raw water doesn't get all that hot in its short trip through the
engine.

Doug
s/v Callista

"Bruce in Alaska" wrote in message
...
In article ,
Wayne.B wrote:

Showering with engine water? It might work out OK but there's at
least some risk of getting rust and scale in your plumbing system, and
temperature regulation might be problematic as your engine thermostat
regulates itself. You will also be unable to turn the shower off or
regulate the flow rate. The flow constriction may even cause your
engine to overheat.

I think most people would opt for a conventional water tank with a
heating loop just for esthetic reasons. A 5 gallon tank is enough for
one or two brief showers, and yes, running the engine will extend your
shower time. My last boat had a 10 gallon tank and that was more than
enough with 2 people on board.

One thing that might be considered here is to use the engine cooling
water, in a closed secondary cooling loop, thru the Hot water tank.
We use this type of system for heating water for remote cabins in
alaska. You would run the engine to heat the water in the domestic
hot water tank, via a secondary engine cooling loop. I have a really
nice Onan 3kw Genset that provides power for my Remote Cabin. It
was originally a Marine Genset with water cooling thru a heat exhanger.
I scrapped the Raw Water Wet Exhaust, and added two Radiators with
electric fans, (one inside the cabin) to the Primary cooling loop, and
run the Secondary cooling loop thru a 20 turn 6" diameter 3/4" copper
pipe that is inside the domestic Hot Water Tank for the cabin. The
Generator powers a 2.6Kw Inverter/Barttery system for power, and heats
the cabin interior via one Radiator/electric fan, until the cabins
interior temp comes up to 72F, then the fan shuts off and the heat
goes thru the heat exchanger to the secondary loop to the Hot water
tank until it comes up to 160F. Then the electric fan on the exterior
radiator turns on and dumps the heat to the outside air. Usually takes
about two hours to heat the cabin from atmospheric cold, and bring the
domestic hot water tank up to temp. this is very close to the amount
of time for the inverter to rechage the Battery bank back to 90%, as
well. Very efficent system.

Bruce in alaska
--
add a 2 before @