I’d like to try a 11 1/2 pitch or 11 just so I can see if I can run the motor less hard. But speed is typically dictated by hull design. To overcome that you must use brute-force. But I’m curious about a little less pitch on this boat.
Greg
Here’s some information I gathered on six props I was comparing. All runs were made six times. The tach used was the type that wraps around a spark plug wire and seems to be very consistent. Speed is by GPS. I really couldn’t tell much difference in rpm by ear. I’m not sure who made some of the props but all were in good shape. The boat is a 1958 Feather Craft Vagabond and my motor is a 1957 35 hp Johnson.
8-26-2016 propeller testing.
10 x 14 2 blade brass prop. 4830rpm speed 29mph AJC prop
10.375 x 13.25 file sharpened 4680rpm 29 and 30 saw 31mph twice PropCo prop G-11
10.5 x 13 4500rpm speed 28mph
10.375 x 14 4500rpm speed 28mph
Unkown prop 4740 rpm speed 28+mph
Real Carol prop 5100rpm 28mph. must be about 12 inch pitch.
