kicker motor prop help

[brook trout]

I have a 92 9.9 yamaha kicker for my 22 ft sportcarft walkaround fiberglass boat. It runs really well but I believe could use a different prop for trolling my heavy boat. Some background on the motor: it has many hours on it and maybe a tad tired but i doubt it coming from a yamaha. It pushes my boat fine for trolling but i believe I have to throttle it higher than it should be to troll especially pulling 4 dipsy's and 4 riggers. Maybe its just too small but I don't want to put anything heavier on there right now. I could find a 15 with the same weight but don't want too if need be. I put it on my 14ft aluminum boat once and it wouldn't get it on plane so I know the prop wasn't letting the RPM's get high enough.
The prop I believe is original. With probably 2000 hours on it maybe the prop is weak?

My question is this: Will a prop that lets my motor tread less water give me better performance? OR a prop that takes a bigger bite do better? I've seen those "big foot" props they look large in diameter but skinny on prop pitch. Can I go to something like this?

The prop reads 9 1/4 X 9-J.

They make a 9 1/4 X 8 & a 9 1/4 X 10 1/2 for this motor.

Anyone have any experience with this? I appreciate this in advance!

Keith

 

[WillyBWright]

Re: kicker motor prop help

Conventional 2-strokes are poor performers at low RPMs. You get more Hp and better efficiency with more RPMs. Going steeper in pitch would be a mistake. You need to get those revs up. The lower the pitch, the better. That's alotta boat for a 9.9.

 

[Silvertip]

Re: kicker motor prop help

And pulling four downriggers besides. You are essentially dragging four little anchors and attempting to push a big boat besides. Let that little engine rev -- it will live longer.

 

[brook trout]

Re: kicker motor prop help

Thanks fellas for the advice. It does rev up, and I guess thats a good thing, so the 9 1/4 X 9 is the best pitch then for this application?

 

[Silvertip]

Re: kicker motor prop help

Without a tachometer to tell you how high the engine is actually reving, there is no way to tell whether its really the absolute best. If you are running the motor wide open to get the speed you need, I would suggest you stop at a dealer and see if they have a 10-1/2P you could try. If the engine seems to labor or lug with that prop I'd go back to the original. However, if you DO NOT currently have to run the motor wide open to provide the trolling speed you are looking for, leave it as it is.

 

[brook trout]

Re: kicker motor prop help

thanks silvertip!

I do not need to run it full throttle, I actually run it about half for 2.5- 2.8 mph on the GPS in one foot waves. I think the last couple years I have been using two more dipsy divers for fishing and that extra pull has made the difference in using more throttle than before. I was thinking that the current prop then maybe wasn't the right one for trolling ETC..

But the way it sounds, i'll stick with what i got.

Thanks!

BT