It could be anywhere. Usually people put them around the engine
room though. I would look for the heat exchanger
on the engine
, see if it's got freshwater lines for heating
, and follow that back to the water heater. Also, follow the lines from the water tank. Then again, maybe you don't have one. Do you have a 110v breaker labeled 'water heater'? Does the water get hot when you run the engine or turn all the breakers on?