A Quick Follow-up Regarding Calder's Calculations
I dug out my copy of Calder's Cruising Handbook, and he has more than five pages of text and formulas he used when deciding on the prop for his PSC 40, NADA.
Bottom line: Calder went with a three-bladed fixed 18-inch prop with a 12-inch pitch. He claimed it provided 7 knots at 3,000 rpm and topped out at 8 knots (He must have really been running that Yanmar hard to do that).
PSC 40 -- #46