Prop and what does what

[champ20B]

what is Double cupping ?

ive heard this said many many times, and cannot understand how you can double cup a single blade.

someone here will probably explain it nice and easy..
or is a double cupped prop just a bit more agressively cupped than normal ?
looking on the net there is too many different answers, and most don't know their arse from their elbow.

Cupping is a curled up lip @ only a few degrees (around [3] I suppose). This helps to hold water on the blade when it is running out of the water a bit, and adds a theortical increase of pitch around (+1) inch.This is to simply increase efficiency with less slip. This is not to be looked at as a speed increase, but as an RPM reducer of approximately 200 RPM. Double cupping is something that is not often seen, as it is a very aggressive cup that can be up to twice the standard. It would be a good idea to discuss it with a propeller expert from a reputable shop, if one feels that a regular cupping isn't sufficiently doing the job. Double cupping can "otherwise" have a very negative effect on performance. I hope this answer is accurate.

[pdt]

yeah already know what cupping was, just never sure what people meant by double cupped.

[fs5]

a lot of guys run double cup over here for racing in the surf and soppy offshore stuff.