Adding cup to a prop.

Suprathepeg

Petty Officer 1st Class
Joined
May 25, 2015
Messages
259
Is it viable to add some cup to a prop? If so what results can be expected?
 

Frank Acampora

Supreme Mariner
Joined
Jan 19, 2007
Messages
12,004
If you need cup, a prop shop can do it so yes, it is reasonable to consider it. Cupping has the same effect as adding pitch so engine RPM will drop. If you are already correctly propped, top speed may drop a bit. Cupping also helps the prop "hold" the water better.Thus, if you have a problem with prop ventilation, while it may not completely eliminate the problem it certainly will help to lessen it.
 

SkiDad

Lieutenant Commander
Joined
Jul 18, 2010
Messages
1,518
Just had it done to my stainless prop this past week. It already had some cupping but not enough. Now my bow rides higher and no blow out in the turns. Cruise was a little improved dropped 100 rpm. If I had to do it aluminum I would probably just look at a turning point hustler prop. Those have a lot of cupping for aluminum but those props run higher than they say so drop down a size if you go that route.
 

Texasmark

Supreme Mariner
Joined
Dec 20, 2005
Messages
14,544
I am a cupping is the only way to go guy. With that said, I have seen articles on the subject and it's a lot more complicated than just bending the blade tips in. If you buy a cupped prop it probably has gone through adequate testing to ensure it works. If you have a prop shop do it you are in a hit and miss situation I would think. On any combination of boat, engine, prop, load....bla bla bla, you are just speculating until you get it on the water; educated speculation mind you but speculation none the less. Around the Dallas Metroplex James' Propeller Service (now in Carrollton, TX..... just up the road from Big D), has been in business 40+ years and if anyone can guess, and get it right he probably can.
 
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