prop re-pitch

[beckoning]

I have a good story to tell, and maybe something that will save others a headache later.

I fish on Lake Michigan using a 9.9hp trolling motor after getting to the "hole" using the 100hp. For 4 years I've struggled with the trolling motor running so slow (2.0-2.5 mph) that after an hour it loads up and quits. I was prepared to install a trolling plate, then a good friend recommended taking pitch out of the prop instead of installing a trolling plate or using a bag. Bags are a hassle, and trolling plates have their own issues, namely getting sucked into the prop if inadvertently the motor is put into reverse, and mounting the plate weakens the cavitation plate. I had the prop re-pitched 2" to increase rpm about 300-500 for a given speed, and it works like a charm. Also, the boat holds direction much better with the re-pitched prop, apparently because each steering adjustment has less effect on the shallower prop. Re-pitching the prop was $50.

 

[Bondo]

Ayuh,..... My prop guy says he can beat a prop pitch, up or down 'bout 1",....

Anymore than that, buy the right prop,....

Glad yer issue was an easy fix,....

 

[Sea Rider]

My prop guy says he can beat a prop pitch, up or down 'bout 1", Anymore than that, buy the right prop.

It is possible to repitch props in 0.5" sizes, or it's usually done in full 1" sizes ?

Happy Boating

 

[Bondo]

It is possible to repitch props in 0.5" sizes, or it's usually done in full 1" sizes ?

Happy Boating

Ayuh,..... Rex could probably give ya a 1/4" either way, through repitchin' it or addin' or flattenin' the cup,....

My point is, a prop blade pitch, starts at the root of the blade, at the barrel,....
'n an inch either side of the pitch cast into the prop is 'bout the most you can ask for,....

 

[ahicks]

Guys I used to work with used to use your rpms in any discussions. Where you were at, and where you wanted to be. Exact size didn't play into it much. If you tell them you're 200 rpm from your target (either way), they could accommodate you. They would guarantee their results. If the first try didn't work out as planned, they'd try again. They would/could adjust cupping, pitch and diameter for fine tuning to your exact needs.

And yes, you have to start with something reasonably close. Repitching a 23" prop to a 17" for instance, is not going to work out.

 

[jimmbo]

A repitched prop, say a 10" beat into an 9", rarely works as well a prop that was 9 from the start. I am not say props can't be tweaked(cupping) but wholesale blade changes rarely work well. The OP was trying to attain a low boat speed without the engine loading up. A switch to a lower pitch prop, there are many for the 9.9 engines, would accomplish the same thing with lower risk of the blades being less than identical