Prop Size

[meanda46]

I have a 46 footer weighing 19 tonne. It has a Perkins 120 with a governed speed of 2800rpm and a 2:1 73 series B.W. box. My prop is way too pitched at 22inch Dia. and a pitch of 24 inches. I am guessing it should be in the 16-18 inch pitch range. Does anyone else have a similar setup that works well. I have no tacho at the moment but it sounds like at full throttle I would still be under 1500 or so revs and 5.5kn is the best it will do.
Thanks.

[nhschneider]

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 45A transmission 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.