Well I’m sure that they can charge it when docked. Would be idiotic if they didn’t factor that in, given how much time yachts spend docked.

And marine diesel engines also usually run at a fairly steady speed, they don’t really get revved up. The big ones anyway, I mean. In diesel-electric systems you can run the diesel engine at its most efficient speed to power the electrical system which is what actually moves the ship.

So I think it’s a net good… compared to a straight diesel yacht. But obviously the better option would be no yacht.