Modify prop diameter. Home machine shop.

[Umassot50]

I have a small hub chopper prop for a 13 spline omc but the diameter is almost too large for my case. Almost hits the cav plate. I want to take about a half inch off the diameter. I have a machine shop and would jig the prop on a rotary plate and mill off the od. Anyone see any problem with that?

[roadkill636]

If the prop already clears. Then why cut anything off of it?

[Umassot50]

If the prop already clears. Then why cut anything off of it?

It only clears because i took the small turn fin or whatever it is off under there. Its dangerously close. I think its too much diameter for the motor too.

[roadkill636]

Its common to remove the trim fin with a larger prop with lots of rake. If it clears all is fine. Iv ran full 16" diameter props with only 1/8" clearance from prop to case. No problem. The prop aint gunna grow.
And cutting off the outside of a good prop is really going to take away the performance of the prop.

[vnemous]

you will remove any cup from the tips and have to have it redone for any lift JMO

[FORBESAUTO]

You can cut it any way you want, but need to make sure each blade is the same and prop is balanced afterwards. Get one blade the way you want it, spray it with WD-40 and put a thick coat of bondo on blade up to and on hub also. After it dries trim the edges to match blade and pop it off the blade. Now you have a pattern of your good blade to match the others to, even the shape and contours. Once your done you will have to cup the tips back like vnemous said. ( You could make a pattern of old tip before you start for reference also) You can also do this to a good prop that is a runner to have as a pattern if you ever mess it up or loose it.

[FORBESAUTO]

Are you running it on the surface? If so you may want to play with the amount of cup on tip. I have found that " loose" is fast. Seems like tighter cups to no cup on tip, but cup on trailing edge is faster on surface. I feel a lot of cup, if your hull has good natural lift, is less efficient. Of course you need enough cup to pack boat, but no extra.

[vnemous]

If your not running fast enough to surface the chopper you will probably just ruin a otherwise good wheel. Whats the boat, motor, speed and rpm. Maybe a different prop would be better. People always looking for a good, clean, unmolested chopper. JMO