Prop pitch

knouse94

Petty Officer 3rd Class
Joined
Aug 28, 2010
Messages
88
I have a 15.5 ft fiberglass bass boat. It is a small boat and I have a 70hp Johnson on it. The motor runs great idles smooth does not cut out. I have played with my tilt and have the motor where it should be. My tach does not work so I have no rpms but the motor seems to be struggling to push a 17 pitch prop. With this prop I am only running between 25-30 mph. The motor had a 21 pitch on it when I bought it and that prop about killed the motor. The 17 pitch prop that I have running is new with no problems. Should I go down to a 15 pitch or 13 pitch. I know this would be a guess without rpms. I just want an educated guess from someone smarter than me. Thanks
 

Pecenje

Seaman Apprentice
Joined
Jul 1, 2011
Messages
41
Re: Prop pitch

your boat could be water logged...

also have you rebuilt the carbs?

the tach will be your best bet...
 

BonairII

Commander
Joined
Jun 7, 2011
Messages
2,727
Re: Prop pitch

Def get a tach. You don't want to end up being underpropped and be over revving your motor. Is it possible that you have cylinder(s) not firing? That would def explain why your motor is having probs pushing your boat.
 
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