Wow, thanks. I was about ready to give up hope so this is very heartening! PM's sent.
It is a very small engine
(7hp) on a small (but heavy) boat, a Cape Dory
28 weighing in at 9-10,000lbs. I got the boat without engine
or prop so I'm starting blind here but 12 x 8 is what I was told by a couple prop guys. I'm not likely to do a lot of motor-sailing so the prop isn't a great concern to me. It will be nice to have in tight spots but I am a bit concerned that being so underpowered will mean the engine isn't doing much in heavy seas where I might need it most. Can anyone familiar with two-vs-three blade props give me a sense of how these numbers would change for a two blade, or is it more complicated than a simple conversion? As I understand it you just need a bit more surface area on each blade to make up roughly the same area for the entire prop?