This prop looks like an early (mid 80's) Yamaha SWS series with the black teflon coating removed, and can be easily re-hubbed for Mercury inline 6 motors if it's not already. This is a good stern-lifting prop.
As to being the right pitch, what's your current lower unit gear ratio? What year is your Merc 115? Does it have the original lower unit?
Give me your current gear ratio, or current performance (prop type, diameter and pitch, current max rpm, top speed, time to plane, etc.), and I'll can tell you your current gear ratio, and give you some suggestions for good props for your motor setup, as well as some tuner tricks for your installation.
I have a newer 90hp Optimax on my '72 Seafari, (actually developing 111 hp/5450 rpm at the prop as just tested), and currently run a 13"X21"P prop. It's an Apollo, and for the Seafari it's really a lousy prop, but I can't afford the new 4B 12.75"DX20"P PowerTech prop I want.
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Common Sense is learning from your mistakes. Wisdom is learning from the other guy's mistakes.
Fr. Frank says:
Jesus liked fishing, too. He even walked on water to get to the boat!
Currently without a SeaCraft
(2) Pompano 12' fishing kayaks
'73 Cobia 18' prototype "Casting Skiff", 70hp Mercury