The 15 hp Johnson motor had a very well used prop on it that gave me 20.5 mph on the 16 ft boat - and it's stamped 9 1/2 x 10. It measures 9 1/2". Beautiful. I ordered a Solas spare for it on Alex's rec that came in a box marked 9 x 10.25, which is what I ordered. New prop gives me 22.2 mph. Fine and dandy and I love it, but the prop is stamped OA 14 21. My Mk I eyeball says it's not even close to 14"....?? It's also stamped with a part # and "Solas." Whaaat ?? Measured it, going from center of hub to tip of one blade, then doubling it - 9". I emailed the seller but they didn't have an answer and referred me to the mfr.
No big deal for now, but in future someone might want to order a spare and what will they go by ?? No way is that little motor going to turn a 14 x 21 prop.
Then I bought this Suzuki 25 hp and it came with 2 props. The one on the motor is stamped Solas, a part # and SB 16 20. No way is that thing 16", so measured it - 9 3/4" diameter. About what I'd expect. I don't have a way to measure pitch.
Spare prop for the Suzy is stamped Turning Point and 12 10. Measured it at 9 3/4".
Any thoughts ?? Seems some strange to me. The old Johnson prop is the only one of 4 that measures what it's stamped.