Prop too big?

[mswidick]

Hi All! New to boat ownership and also this forum. My parents gave me a 2002 pontoon boat with a 2002 Yamaha 60HP 2 cycle, 3 cylinder engine. The engine came with an aluminum prop 13x19. The owners manual for the engine shows WOT at 4800 to 5200 RPMs. I think I may have multiple issues such as throttle linkage and tach readings but at full throttle the tach shows right around 2k RPM and GPS reads around 17mph. The engine does appear to be sound mechanically. It fires up when you turn the key and doesn't miss, sputter or stall. Is my current prop pitch too much for this boat? When I go to prop selector websites and tools such as "yamahapropselector.com" the range for pitch for all around performance is 11 to 13. Is my current propeller pitch of 19 too big for my boat?

 

[jakedaawg]

How.big.of a pontoon. 19p may be right for a 14 footer.

 

[Scott Danforth]

Yes, its too big, especially since your lugging the motor down to 2000 RPM. thats hard on the motor

 

[Sea Rider]

Yep, extreme low rpm, need a prop to pull wot revs around middle or max 5200 wot range. Try a 11 pitch per prop selector recommendation and check achieved max wot revs as loaded. At least will know how much wot rpm the 11 achieved compared to the 19.

Running OB's at the extreme lugging side is like pretending going up hill on third gear from a flat stop. Too much stress on pistons and rods which is no bueno..

Happy Boating

 

[mswidick]

Thanks for the quick feedback. Looks like I'll be getting a new prop.

 

[Sea Rider]

For the record post max wot rpm achieved as usually loaded with new 11 prop, if OB way over revs max wot rpm can have it repitched at a prop shop to 12 pitch to decrease wot revs. Only possible to know on a water test.

Happy Boating

 

[ttankmoran]

I run the same engine on a fishing boat and I see 36 MPH at about 5700-5800 RPM with a yamaha 17P Aluminum. You are WAY! over-propped I would start off with an 11 or 13 pitch prop and see where you sit. I would guess your tach is off too. 17 mph with a 19P at only 2000 RPM is mathematically impossible, I would guess you are closer to about 3000 RPM.