Stoopid prop question

[BoatBuoy]

It's probably a lame question but somehow along the way I missed it. I often see the term "cup" or "cupped" used when discussing props. What exactly is this. Also, with 2 otherwise identical props, what would be the expected difference between a cupped and non-cupped.

 

[WillyBWright]

Re: Stoopid prop question

Cupping is a performance improvement. I adds to a propeller's pitch and gives the prop a bit more bite in the water. It's most commonly used on planing boats. It's readily apparent by the curling of the trailing edge of each blade.

 

[Dhadley]

Re: Stoopid prop question

Well, it does add bite but doesnt change the actual running or progression of the pitch. It helps hold the water on the blade (better bite) and can usually be run at a higher X dimension for less drag. Some props run the cup out to the tip, some to the middle and some beyond the tip.<br /><br />There are also different styles of cup. Some props just have the trailing edge bent. Some create the cup with more material and create what is called a "J" cup.<br /><br />Basically cup is a tool to increase a particular prop's efficiency. <br /><br />Not a bad question at all.

 

[Jdeagro]

Re: Stoopid prop question

The January issue of Bass & walleye Magazine has a very good article explaining pro design and the effects.