Diesel electric is a well proven way to go. Not only can you drive the boat with the generator but you also have plenty of power. I assume the alternator is 3 phase.
You will have to have a good idea of what your total load will be and ensure you do not run too much on the genset.
Well you can have the best of all worlds. The optimum would be twin screw using a pair of 5 Kw motors. Drive each with a VFD and you have variable speed, reversing etc etc.
OR you can have single 10 Kw and again drive with VFD and 3 phase motor. That will give you about 12 HP which may not sound like much but that equates to 24 HP in an engine. You may still be a little underpowered for a 43 foot but it is a sailboat and you are supposed to be sailing and not listening to that dang diesel banging away.
I live aboard a Newport 30 in Seattle so I know a few things about sailboats also,
I recommend 3 phase because you have no brushes commutator water problems (well a lot less than with DC motors).
I am an industrial electrician and learned the trade on submarines.
Dan Bentler
Mar 31, 2009 Rating
Boat power by: Anonymous
13 kw is partway between 15 and 20 hp. Go 3 phase if possible for efficiency. The only serious constraint I see is max revolutions for your screw. The ac controllers are awesome. You can generally overspeed them by a factor of 2 (subtract 20% power for continuous running at this speed)
