cupped props

[Miss Rita]

Even though it's the middle of snow skiing season for me, water skiing isn't that far off.

I know what a cupped prop is, but what does it mean when the cup is described as "0.09", "0.11", or "0.12"? Enquiring minds need to know.

[Jeff Lyman]

I should know this but dont. I would guess the higher the number the more cup in the prop. The cup is at the leading edges or tip of the prop and always progessive. More cup produces more forward thrust and "bite" in the water as the prop spins. Over cupping thus lowers rpm's and inturn at some point will lower speed. There's a fine edge to this science of how far to go before it's to much. I've had many props recupped up an down but never remember discussing numbers like those, but always to dial in rpm's.

[Jeff Lyman]

Lucky you have snow to ski!!!