Prop size
I sympathize. We have a 1976 Hunter 30 with a new 25 HP Vetus diesel. I Have been working on prop sizing for weeks, and I can't get the same answer from any two people. I know the distance between the tip of the prop and the underside of the hull has to be at least 15% of the diameter of the prop. Everything else is pls or minus (+/-) a hammer handle. I have heard everything from a two blade 13" 9 pitch to a three blade 14" 10 pitch based upon my motor size. Look for a place that has prop scan software, thats a little better than an guess. They need displacement, length at waterline, gear ratio, Horse power, RPM's at wide open throttle, and they can come pretty close. Sorry I couldnt help more