25 yamaha 3 cylinder

[leafman]

25 yamaha 3 cylinder 2 stroke 2000
9 7/8 x 14 aluminum prop
1546 xpress flat bottom boat
4 inch setback jack plate
fin level with bottom of boat
WOT RPM unknown

Holeshot is sluggish
WOT MPH 33 empty

I will purchase a tiny tach when I purchase a new SS prop. My understanding is I can have a prop repitched up or down 2 inches. I have access to a prop shop and will purchase a powertech propeller unless someone has a better suggestion with proven results on similar size setup. Should I get a 12 or 13 pitch prop to start with? I would like to improve the holeshot and still maintain 28-30 mph with a normal load.

 

[steelespike]

Re: 25 yamaha 3 cylinder

You would be better off getting the tach first.Is your speed by gps?
I can estimate your rpm by your speed,gear ratio,pitch and guessing 6% slip
the calculator says about 4900 rpm A 12" prop should add about 400 rpm
perhaps more on a smallish motor. using the same 6% slip, that computes to a little over 30.
Should improve hole shot and stay on plane easier at reduced throttle.
A repitch can be a bit of a comprimise. You might consider repitching your present prop
and make your desision based on the resaults.