Correct Prop for 40HP Mercury Force

[hckrphil]

I have a 40HP Mercury Force outboard.<br /><br />WOT tests indicate I'm running at 34MPH at 4700RPM.<br /><br />The current prop has a 13-1/2 pitch to it.<br /><br />I know if I decrease the pitch of the prop, the RPM's will increase. <br /><br />By doing this, will I be effectively utilizing the entire spectrum range of the engine? Does anyone know the max RPMs that this engine should be using?<br /><br />If I decrease the pitch, will it help or hinder me getting up on plane better?<br /><br />If I decrease the pitch, will I be able to squeak out a few more MPH at higher RPMs?<br /><br />Thanks in advance.<br /><br />~Phil

 

[roscoe]

Re: Correct Prop for 40HP Mercury Force

Recommended rpm is 4750-5250.<br /><br />Lowering to 11 pitch should put your rpm at 5200, increase holeshot / help planing, top end will likely stay the same, perhaps increase by a mph.

 

[hckrphil]

Re: Correct Prop for 40HP Mercury Force

Hey. Thanks for the reply.<br /><br />So you think I should skip the 12-1/2 pitch prop and shoot right down to the 11?<br /><br />Know where I can get a good / used / cheap prop? I've checked ebay but didn't come up with anything.<br /><br />Thanks!<br /><br />~Phil

 

[roscoe]

Re: Correct Prop for 40HP Mercury Force

You are running at the low end of recommended rpm now with the 13.5.<br /><br />A 12 or 12.5 will put you right in the recommended range, and an 11 will put you near the top. The lower pitch you go, the better holeshot you will have.<br /><br />If you are happy with the hole shot now with the 13.5, then stick with that or something close. If you need a better holeshot, then lower the pitch. <br /><br />Likely not to see any significant mph change.<br /><br />By the way, this is a bad week for ebay (holiday weekend). It should pick up next week.

 

[hckrphil]

Re: Correct Prop for 40HP Mercury Force

Thanks Roscoe!<br /><br />Actually, my hole shot SUCKS.<br /><br />Even with just me in the boat, sometimes i have to stand up just to get it up on plane. I'm looking at getting smart tabs.... that should help, just 130 bucks.<br /><br />I'll just keep an eye out on ebay for the 10-3/8 x 11 pitch prop. <br /><br />Thanks again!<br /><br />~Phil