I have a 21' 1981 Searay Cuddy Cabin (a very heavy boat) that had a 260 Mercruiser I/O. I got the boat for free because the motor was shot. I rebuilt the original 350ci engine, bored it 60/1000 over and put a stroker crank in it with new high compresion heads and a marine cam. Also replaced the Rochester four barrel with a holly double pumper 650cfm. Displacement figures out to be 388ci. It is 10.7:1 compression so I am running 94 octane fuel with lead substitute. I have taken it to the water a few times and it runs great with a good hole shot, but the top end is only 34 knots at 4600rpm. I know very little about props so I asked my local sport shop about it. They told me that I had a 18 pitch prop and the next step up would be 21 and that would be too much for the motor. I find it hard to believe there is no in-between prop for my situation. I can have 6 people in the boat and pull 3 skiers simultaneously and it does not work the boat very hard, but I am wondering if it could do better. I have never changed a prop before, I believe the one I have is stainless steel. Any advice would be great. Thanks!
