I had not thought about that concern. However, the previous owner did have a water heater hooked up, in a position higher than the motor. Re: the muffler - I am new to this, although i am fairly mechanical - lots of auto motor work growing up - My exhaust comes directly out of the engine, where the water hose then joins it, and then goes through a rubber - baffled silencer, and out a seacock on the underside of the boat - not the transom. I should note that there is a high loop, before it exits through the seacock. Is this setup normal - as I don't seem to have a water-lift muffler - Is that only when the exhaust exits the transom?
Does this make mine more or less prone to back-flooding from the water heater?