Wondering about prop size

[bucmac79]

I have a 99' Polar 1996 model skiff with a Yamaha c90. I havent owned the boat too long. I have rebuilt the carbs and got it running really good, but it doesn't seem to have the power that I thought it would with this matchup. In the front storage area is a beat up 13x19 alum prop. On the boat is a 21p prop. The dia isn't stamped on it. The boat doesn't have a tach, so I dont know rpms. It doesn't seem to rev out like my old johnson 115 did though. Any suggestions on the right size would be greatly appreciated. I know that I need to install a tach too for proper sizing.
Thanks

 

[steelespike]

Re: Wondering about prop size

Assuming the Polar 1996 is like a typical 19 ft aluminum boat I think the 21" prop is pretty far up the chart. I think a 17 or 19 would be closer to what you need.
We do need the details of the boat and eventually the prop size,and max rpm and speed.
The only way to be sure your setup is right and final prop selection is correct.

 

[Mi duckdown]

Re: Wondering about prop size

RPM and Speed is critical. Without both, it is a guesing game. and could be costly.

 

[bucmac79]

Re: Wondering about prop size

It is a fiberglass boat. I thought the 21 seemed much. I will install tach and speedo and get more info so I can get it right. Thanks for the help.