I should add... this boat motorsails under genoa really well.

The genoa is big, but sailing down wind it always gets shadowed alot by the main. We have to tack down wind to keep them both filled. It's about 5.5 knots down wind no matter what you do, and less if you consider course made good. But if you crank the diesels on, 1800 rpm, you can motorsail at 8-8.5 knots, and the jib stays filled and doesn't flog around like it does when covered by the main. The engines don't use much fuel at 1800 rpm... probably a gallon an hour for the two of them.