Correct propellor size for my saildrive propeller?

I do have a question. If anybody else has installed a Volvo diesel with a sail drive I would like to know the propeller size they went with. I have a 15×13 fixed 3 blade prop and I think I need a little less pitch. My engine doesn’t get up to its rated revs and overheats if run wide open. Maybe a 15×11 or 16×11 would do better? My engine is a Volvo Penta md17c – 110s 36 hp diesel. It’s 3 cylinder and pushes the boat at about 5.5 knots. I like the engine a lot but have always had this overheating problem. Mine is fresh water cooled (the first the company ever sold in the U.S.) and if the engine overheats the plastic impeller on the fresh water circulating pump becomes loose and spins on the shaft. The only solution I have found it to buy a new pump (now on number 3 at $320.00 each). Is yours fresh water cooled and do you have any of these problems? Thanks, Bill Schwartz, (s/v #090, Moonshadow)

a. I use a 2-bladed prop (16″ diameter x 11″ pitch LH rotation) on my Volvo MD 11c engine (23 HP) and am satisfied with its performance. Cooling water to the saildrive is NOT connected. The engine has NO fresh water cooling. Lester Helmus (s/v #010, Insouciance)