Best prop for 15 HP johnson on 16 ft flat bottom boat

[Jolliff49]

I just purchased a 16 ft flat bottom that has wood floors and is a little heavier than usual. The 15 hp johnson does not seem to be performing that well. The current prop is 8 1/2 X 10. Rpms seem to be low. Just replaced impeller and lower unit oil. Starts easily, just does not run out like it should. Any suggstions? Jim

 

[steelespike]

Re: Best prop for 15 HP johnson on 16 ft flat bottom boat

I can tell you under ideal conditions the 15 can approach 25 mph or more.
With a light load your boat could run around 22-23.Assuming proper setup and a healthy motor.
A 10" prop should work.See if you can get us the info we need. A Tinytach will work on your motor.
They have a web site. Forgot to add to read "read this first" at the top of the page.

 

[Johny25]

Re: Best prop for 15 HP johnson on 16 ft flat bottom boat

My 15hp johnson with a 9.5 X 10 pitch will do ok up to about 900-950 lbs in my 14ft V hull (that is total weight of everything including the motor) and even at that my RPMs were not at the recommended 6000-6250. I was going to get a lower pitch prop for my boat but decided just to get more HP instead

My guess is you need to got to a 9X9 but a tach reading will give you a much better idea of what you need.