Prop Advice

[kian]

I'm looking to replace the prop on my 94 force 40. (Serial number 0E065269). Exhaust is through the trim tab. Boat is a 15' aluminum fishing boat. Current prop looks like it isn't a factory issue. It is a 10 pitch 10 1/2 inch prop. What do people think of going to a 13 pitch 10 1/2 inch prop. Should I consider cupped? What would increasing the diameter do? <br /><br />I don't have a tach or speedo to know about rpm at WOT or speed.

 

[Fouled Plug]

Re: Prop Advice

Glendon, I would locate a dealer in your area with test props, and buy/borrow a tach. Trying to prop a motor by ear could be an expen$ive mi$take.

 

[Spidybot]

Re: Prop Advice

Absolutely correct.<br /><br />You need to know what rpm is rated for your motor and what rpm you acchieve at Wide Open Throttle under normal load.<br /><br />Then you decide how much your rpm needs to be changed and look for a prop that does this. One inch higher pitch causes approx. 200 rpm lower at WOT - and vice versa.<br /><br />This will be your base for choosing.<br /><br />If you like, there is a book on props for free download on this previous post