Re: water heater
How many outboard boats have a shower anyway? For dishes it's easy enough to heat up a little water on the stove.
I have a hot water heater (and a shower) on my Pearson 28-2. If it dies I'll remove it. It's nice to have, but takes up a lot of space in the lazarette, complicates the plumbing, and is almost never hot when I'd actually want hot water, so it is rarely used.
1986 Pearson 28-2 "Elena"