Re-prop
John,I changed the prop on our Cat 30 this spring from a two blade 12x12 to a three blade Campbell Sailor Prop 13x9.I have repowered the boat and it has a Yanmar 2GM (13 H.P.)now with a 2:62x1 trans.To my surprise I actually lost cruising speed and response. The engine will rev to its max under load with no effort and at my normal throttle setting of 3,000 rpm I get 4 knots down from 5.5It is obvious that the prop is not working to its potential and I think a re-pitch will help.I have e-mailed the manufactured ( who is located an hour away from here) but have heard nothing back from them as yet. I also sent an e-mail last night to Catalina for their thughts on what pitch I should go to OR go back to a convential 2 or 3 blade.I think the best thing to try first is the re-pitch which is the least expensive and look at either a 10 in or even 11 inch.Get some pro advise re: make, size and pitch or you will end up like me, trial and error!Cliff CarterPlusOne1977 Cat 30 #598Oak Bay B.C.