Prop question for a newbie , need some advice

[bluebrownie]

hi folks, i have a 15 hp gamefisher... prop is 8 3/8 x 6
my manual says recomended full throttle RPM's is 5500-6500 rpms ( i dont have a gauge on my motor for rpms), horse power rating is 6000 rpm's.
I AM WANTING to pick up some speed... how do i go about doing that? i understand taht if i change the pitch , go higher, i will pick up more speed over the long haul...vs. lower pitch, faster pickup etc... BUT how do i determine if i can go to a higher pitch?
also, how do i know if the prop would fit on my spline...? are they all pretty consistantly the same?
THANKS

 

[Silvertip]

Re: Prop question for a newbie , need some advice

Without a tach you have no idea what RPM the current setup provides. That bit of information is essential for any performance evaluation. You need to know what the engine is doing NOW before you begin messing with props. For all you know you already have the optimum setup. Buy a Tiny Tach and take some wide open throttle rpm readings. Then and only then will you know if there is room for speed increases. Who knows, you might have to decrease pitch to keep from destroying the motor due to lugging. Or increasing pitch to avoid destroying the engine due to over-reving. It may turn out that the only way to increase speed is to get a bigger motor.

 

[bluebrownie]

Re: Prop question for a newbie , need some advice

how do i go about getting a "tiny" tach...? what should i be looking for?

 

[steelespike]

Re: Prop question for a newbie , need some advice

Tinytach has a website.Just read the info and order a tach that is best for your application.
It is an induction tach and there are others. We will also need to know the motor model number
as a number of companies built motors for Sears.I have a feeling it is an Eska and your not likely to find a different prop.Tell us the details about your boat and motor and the performance.
We may be able to make some suggestions.