Cup differences on Props???
 

So the morons at the local ramp have been at it again with powering their boats onto the trailer and have kicked up all of the debris on the bed of the ramp. Loading up yesterday I was about 4 feet from having the boat on the trailer and caught the prop on something and banged it up. I'm going to send it off to be repaired but also pick a new one up so I have an extra. Currently installed is Acme 1235.

I was looking on Acme's site and saw that the 1273 is the same diameter and pitch as the 1235 but the cup is .150 on the 1273 vs the .105 on the 1235. What difference would this make???

The wa it was explained to me is that it works like false pitch. In other words you get same performance, but should reduce RPM's sightly

My understanding is cup is how much water each blade can grab. More cup means more water which equals less cavitation and slip. It is a balancing act because some slip is good because it allows the motor to rev up a bit more on start up which moves it in to a more powerful band

I have a 1631 which is a great prop, I believe it's almost the same as the 1273 but just an inch smaller. Things got balls even with 3k loaded up

simplej, what boat do you have and how much ballast do you run, I am thinking of going with the same prop bc my boat seems to be slightly underpowered pushing my 1234 prop which is 14.25".

Tige rzr with 2375 in water weight plus 4+ people on a PCM ex343 so like 7k+ lbs of boat when all Is said and done

If you change only the cup, and the cup goes to a smaller #, here's what you can expect:
Lower top speed
More out of the hole performance / torque
Takes less time to plane / get to "X" speed
Higher RPM at X speed

Most of us who run heavily weighted boats prefer lower cup numbers.