Re: Inverter for hot water tank
I'm rather confused... your engine circulates its coolant water through the hot water heater, right? But this isn't hot enough for a shower? I realize that having a raw-water cooled engine will likely make it not as warm as the fresh water circuit on my engine, but even the raw water coming out my exhaust is plenty warm enough to shower with (I'd guess about 90 degrees). This isn't what you see?
Others have pretty thoroughly explained the power problems with electrically making hot water while under way, but there's another aspect that hasn't been brought up yet. Even if you did heat your water with electricity, without some plumbing changes, you're still pumping your insufficiently-warm raw water through the hot water heater, which will actually be cooling your hot water!
I plan on having an on-demand propane hot water heater on my next boat for infinite showers, you might want to consider that. There is at least one model approved for use on boats.
1979 Gulfstar 37 Laissez Faire