Pontoon Boat & Deck Boat Forum

I have gone through a couple of tries with new props but can't seem to get it right. Have 20' fisher with a 4stk merc, 60 hp efi (not a bigfoot). Currently running a 101/2 x 12 and can just get to 5k rpm. Seems like I am still missing the top end a bit. Any suggestions?

Sounds like you need a 10 pitch to get rpm's up. That will pick up about 200 rpm's om average. But only true test is try it!

You'll increase your RPMs by 150-200 for each one inch reduction in pitch. A 10 pitch would increase your RPMs 300-400.

What is the max RPM for your outboard?

Have you tried using this?

http://appcenter.mercurymarine.com/propSelector/home.do

You looking for more rpm or top end speed? Just for comparison I first tried a 17p Mirage and could only turn 5300 and 38 mph.
Next tried a 15p enertia and got 6000 at 40mph. Bottom line I only picked up 2 mph with a 700 rpm increase and that is with a 150 and a 3 log boat. Don't mean to discourage you, but I would not blow a lot of money testing different props unless you have someone that will let you test them for free and exchange them. Might go to a 10p and get the rpm up but end up not gaining any speed or possibly loose speed top end. If I haven't said it before "Welcome aboard"
doc

dockholiday wrote:You looking for more rpm or top end speed? Just for comparison I first tried a 17p Mirage and could only turn 5300 and 38 mph.
Next tried a 15p enertia and got 6000 at 40mph. Bottom line I only picked up 2 mph with a 700 rpm increase and that is with a 150 and a 3 log boat. Don't mean to discourage you, but I would not blow a lot of money testing different props unless you have someone that will let you test them for free and exchange them. Might go to a 10p and get the rpm up but end up not gaining any speed or possibly loose speed top end. If I haven't said it before "Welcome aboard"
doc

I'm having the opposite problem----13x16 Merc prop and I still hit the rev limiter if I dont watch it. May be the 25 in logs and the underskinning--it planes out pretty quick. 28 GPS altho I hit 30 one day--combo of good lifting headwind and maybe a little ground effect as I was in about 8-10 ft of water. I May add a little cup to the prop----dunno

wwind3 wrote:

dockholiday wrote:You looking for more rpm or top end speed? Just for comparison I first tried a 17p Mirage and could only turn 5300 and 38 mph.
Next tried a 15p enertia and got 6000 at 40mph. Bottom line I only picked up 2 mph with a 700 rpm increase and that is with a 150 and a 3 log boat. Don't mean to discourage you, but I would not blow a lot of money testing different props unless you have someone that will let you test them for free and exchange them. Might go to a 10p and get the rpm up but end up not gaining any speed or possibly loose speed top end. If I haven't said it before "Welcome aboard"
doc

I'm having the opposite problem----13x16 Merc prop and I still hit the rev limiter if I dont watch it. May be the 25 in logs and the underskinning--it planes out pretty quick. 28 GPS altho I hit 30 one day--combo of good lifting headwind and maybe a little ground effect as I was in about 8-10 ft of water. I May add a little cup to the prop----dunno

Glad you posted that. The 200 to 300 rpm per pitch is just rule of thumb. Lots of variable also enter into the equation. Size of log, motor position, number of logs, and a bunch more I am sure. One 15p may give totally different result than another 15p even made by the same manufacturer. My guess that is why Merc has so many different props, mirage, enertia, vengeance and so on. I am sure there is a little better prop for mine, but not enough to go searching and buying props and having to resale them.