9.9 hp motor + heavy boat , what prop is right for me?

[jvolpe28]

Hello all, I have a 16 ft MFG boat fiberglass and deep, kind of heavy for my motor, 1984 9.9 evinrude, The lake I fish on has a 10 hp limit. My current prop is a 9 1/2 x 10 . For such a heavy load what prop would be best for my situation, I was wondering what dia + pitch to get and how pitch would be a factor, ...thanks for any help

 

[Yepblaze]

Re: 9.9 hp motor + heavy boat , what prop is right for me?

Get yourself one of those tiny tach(s)<br /><br /> http://www.tinytach.com/origgas.html <br /><br />Stick it to the motor so you can get an idea of the RPMs it's turning with the prop you have then get back this forum and I'm sure someone might be able to give you appropriate pitch adjustment amounts.

 

[Boatist]

Re: 9.9 hp motor + heavy boat , what prop is right for me?

Hello<br />Not sure I can answer your question but I can give you a little info. I have a 15HP 1975 Johnson, same motor you have with a different carb. It came with a 9 and 1/2 by 10 3 blade aluminum prop, p/n 386118. I used motor on a 14 foot aluminum boat and it would plane with 2 people and fishing gear but not plane with 3 and fishing gear. I got a 9 and 3/8 by 9 3 blade stainless steel prop, P/N 389892 $130 in 1993. It was thinner and cupped on edges so could run motor a little higher. With that prop boat would plane with 3 people and light fishing gear but still not with heavy fishing gear. Since then I haved moved motor to a 21 foot Aluminum runabout that weigh about 2800 lb. Motor will push boat about 9 mph wide open. This boat we use alot for offshore fishing, 15 hp is for saftey should main motor fail some trolling and a lot of backing to slow our drift when wind kicks up over 20 mph. The motor did not back up very well even if opened it up, and if opened it up would throw water all over back fisherman when prop came out of water on the back side of swells. I got a another prop it is 10 by 9 by 4 blade aluminum P/N 176266. With this prop boats foward speed is about the same but in reverse will hold boat against winds up to 30 and just off idel. The prop is suppose to have 60% increased reverse thrust. Also if we go to inland lakes and I use it to move boat for bass fishing works much better in foward and reverse. This prop vents exhaust gas away from prop in reverse. One thing it does not have that other two do is a fishing line cutter to keep line from wrapping around prop. For out 21 foot deep v Aluminum boat I like this prop the best. Like I said I do not know if this helps but it is a little info. all part numbers are OMC/Johnson.

 

[steelespike]

Re: 9.9 hp motor + heavy boat , what prop is right for me?

consider adding a ducted prop setup, there are a number of styles, supposed to be good for increasing efficiency of slow moving boats and pontoons.Also can protect prop.