Prop for 1985 30 Horsepower Johnson, no tachometer

[paceac]

I need to try and figure out what pitch prop I need and I don't have a tachometer. The boat is a 15' aluminum Gregor and would weigh about 900 with two passengers. I don't need to go super fast but just want a prop that won't put too much stress on the engine. I just bought the boat and there was a 10" 15 pitch but the prop is old and slips. I don't know if this was the original prop. Any suggestions? Anybody have this engine on a similar boat? Thanks

 

[G DANE]

Re: Prop for 1985 30 Horsepower Johnson, no tachometer

From my experience that 10X15 has been lugging the motor. Go for a 10X13, at least. You can get a "TINY TACH" for few $. The motor will live longest if capable at at least 5500 RPM. Many prop shops would be willing to let you test a prop and swap to another pitch. Decarb the motor once a year.

 

[cobra 3.0]

Re: Prop for 1985 30 Horsepower Johnson, no tachometer

I had almost the same set up. 10x15" lugged the motor. 10x13" was perfect.

 

[BillP]

Re: Prop for 1985 30 Horsepower Johnson, no tachometer

An aluminum 3 blade 10D x 15P prop is the original prop shipped with the motor from the factory.

 

[paceac]

Re: Prop for 1985 30 Horsepower Johnson, no tachometer

Thanks a bunch guys. I think I'll go with the 10x13.