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25HP Yamaha 4-stroke Prop problem

Howdy all,

I have a problem. I have a new 25HP 4-stroke Yamaha outboard mounted on a 14' Express that I run in saltwater 90% of the time. The factory aluminum propeller is 9-7/8 x 10-1/2. The new motor came with a SST propeller but I did a bad thing. I asked the dealer to sell me a 9 x 13 propeller thinking that I could get more speed out of my boat (took a 35HP 2 stroke off due to motor failure). The WOT range for the engine is 5,500 - 6,000 RPM. I could barely make 5,000 rpm and my holeshot was gone with the new SST prop. So I asked the dealer to have the prop re-pitched. They took 2 degrees off of the pitch (at least that is what I was told) and the reult is that the holeshot is still gone (takes forever to get up on plane) and when it's finally on plane the max RPM that I can get out of it is 5,300. With the aluminum prop the boat pops right up and max RPM is 6,000. In either case the max speed is around 23 - 25 mph.

Here is my dillema. The prop that the dealer was going to supply had an 11 degree pitch but I don't remember the diameter. I found a 10-1/2 x 11 (for a Yamaha 4 stroke) on this site that is reasonably priced but I am not sure how the slightly larger diameter is going affect the performance of the boat.

I realize that I should have let the dealer supply me with what he wanted to supply me. But I didn't so it's going to cost me. Live and learn.

Any help on the balck art of selecting a propeller would be greatly appreciated

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Topic - 25HP Yamaha 4-stroke Prop problem - Mike6158 11:50:12 08/14/04 (0)

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