Difference between 13x13 and 13x13 cup?

[bens250ex]

What's the difference I have both sitting here and I can visually see the cup one is cupped but what difference is it going to make on the boat? This is on a comp.

[crystal waters]

A cupped prop will give you more pitch to the trailing edge of your prop.
It will give you the same effect as having more torque to pull with such as pulling a skier out of the water in short order.
(more bite!)
That said, it will in turn affect your top speed a bit.

[bens250ex]

Ok I might give it a try see how it acts

[wiatowski]

ones cupped ones not... lol
seriously though from my research cupping basically is the equivalent to adding 1" to your pitch, plus has the added bite as mentioned above.
On an i/o you can have a 3 blade prop 13 pitch, but a 4 blade 13 is more like a 14.