the results aint in yet.

[mouse action]

howdy all,new to this whole boat thing so we started out small,we got a 14 ft alum sears ****fisher with a 2 stroke evenrude 7.5 hp and was having lots of fun till I felt it was time to step it up,so we got a 03 yamaha 15 hp four stroke,well Im not to impressed.runs great,very quiet ,gas mizer,but vibrates your fillings out of your mouth.and not so fast as I expected.is there a proper prop set up that Im missing out on?Im not sure what I have.

[marcortez]

2-1 odds the prop is causing the vibration.
It is bent or tweeked and causes high RPM vibration.
Even a little ding or bent blades can cause some vibration at speed.

Runs like a dream at low speed right?....no vibration?
When you open it up....the vibration starts?

You might see mid/high ****s in the top speed...on plane certainly.

[mouse action]

the vibes seem to be there all the time,it really dont feel like a bent prop.just a constant vibe.maybe its a alum boat thing, it just dont jump like a two stroke,planes off right away,I just thought a 15 hp would scare the pants off me in a lite boat like this.that why Im wondering if theres a formula for props to boat ratio ????????

[Reel Insane]

My flat boat had the same vibration you are describing. When I removed my prop I noticed my hub was defective. Sent to the prop shop and had a new hub installed, balanced, and painted. Boat runs smooth and performance improved as well once I got the cupping on the blades reworked.