Best prop for old Thompson

[mercruiseralpahmaniac]

I have a Thompson 260 with a small block chevy and an alpha one. i had a 15x17 three blade prop and i could get 30mph at 4500rpm. prop went to hell thanks to a dead head so i threw a 15.25x15 on because it was the only thing i had. huge difference and instantly regretted it at 5000rpm i could only get 20mph. my question is if i went to a 15x19 prop would i see as much of an improvement going from 15 to 17 or will i be shooting myself in the foot?

any opinions would be nice

 

[Scott06]

Shooting your self in the foot. With a 19" I would expect rpms to drop 400 vs the 17". If your tach is accurate stay with a 17" otherwise you'll be lugging the engine, take longer to plane, and probably loose top speed.

 

[tpenfield]

Hole in the foot. I think 15x17 is the right prop for that boat. The challenge is that the boat is under powered, so getting away from the optimum prop is going to result in a dramatic performance loss.