All of the manufacturers of folding props (and their equivalents like the flexible plastic Kiwi Prop) have a spot on their website where you can get a recommendation for the optimum prop based on factors like boat size, type, and weight, engine HP and max RPM, etc.
Since you are looking for a replacement for a fixed prop, I decided to look at the website for Michigan Wheel to see if they offered the same service. They do. The web link is: http://www.miwheel.com/propellers/prop-it-right/ It is actually a very complete questionnaire and asks questions about your boat and engine (as do the other sites I've used), but in addition it asks why you are replacing the old prop and what you want to accomplish by changing. It also asks what diameter prop you want. I'm kind of surprised you have a 15" diameter prop when the OEM props were 12 or 14. I know a J/30 with Yanmar 3GMF15 and 7/8 dia shaft uses a 12x9 2 blade prop. If 1" of diameter has effect roughly equivalent to 2" of pitch (which I understand to be the rule of thumb) then a 15" prop with the same thrust would be something like a 15x3 or 15x4 - and that's not very plausible. I wonder if your boat is over propped. Have you noticed and a "thumping" noise or vibration at higher RPMs? Can you get max RPM out of the engine when in gear? Do you get hull speed at the RPM of max torque (somewhere near 80% of max engine RPM, usually)? Go to a prop manufacturer and see what they consider optimal for your boat. Someone else suggested taking your prop to a prop shop for measurement. I'd also encourage taking it to a prop shop so they can evaluate the likely cause of the damage. You're in fresh water and out of the water for at least 6 months a year, so I wouldn't expect corrosion to be a normal issue. Heck, my 38 has spent almost all of the last 20 years in salt water (24/7/365 for a couple of years at a time, then hauled for bottom paint) and the bronze prop has some barnacle circles o n it, but no evidence of corrosion. If you have corrosion from a "hot" marina it would be prudent to take a close look at all the bronze through hull fittings in addition to the prop. Rick Brass Imzadi -1976 C&C 38 mk1 la Belle Aurore -1975 C&C 25 mk1 Washington, NC At 07:53 AM 26/11/2013, you wrote: Hello all I have been watching the list for a while but never contributed until now. Couple years ago we bought a 1980 C&C 30 MKI from the original owner. wonderful wonderful boat! This was our first boat and things have been a bit daunting at times- but I cant tell you how much the list helps. When we pulled her this year we had some serious prop corrosion issues. We are still trying to assess the cause (anode was replaced last spring but perhaps I didn't get good contact)but regardless we will need to replace the prop. It is a 15 inch radius 2 blade fixed but the erosion is such that I cannot read the pitch- how do I figure this out? Any suggestions as to suppliers as well?- we will likely stick with the 2 blade fixed. has any one had experience with the urethane perfect pitch props? Thanks in advance Joanne Dowd SV Islay Hamilton ON Sent from Windows Mail _______________________________________________ This List is provided by the C&C Photo Album http://www.cncphotoalbum.com <http://www.cncphotoalbum.com/> [email protected]
_______________________________________________ This List is provided by the C&C Photo Album http://www.cncphotoalbum.com [email protected]
