I have a 48' ketch
that weighs about the same amount and has a 37' waterline. I just installed a Beta Marine
90 that's supposed to develop 90 horsepower at 2,600 RPM
. It's coupled to a ZF Hurth
that's set for a 2.43 ratio. At the same time, I installed a Gori 24"x18" 3-bladed prop. It's pretty close to being right. WOT (Wide Open Throttle) I can get up to 2,400 RPM
and I'm running at 8 knots, just .3 knots off hull speed
. If I were to do it over again, I think I may have ordered a 17"-pitched prop but I think I've got things pretty close for my boat.
Fair winds and calm seas.