I currently have 15X21 3 blade cleavers on Speedy II's, what would be the effect of going to a 3 blade cleaver 16X24? Would it be any easier coming out of the hole with a bigger dia and pitch?

That seems to be a whole lot more prop. Did you make HP gains? What kind of boat is this on?

Thats probably a 1000 rpm difference in props at WOT.

boat is a 1980 38 scarab. motors are twin turbo 454 making approx 550 hp hooked to speedy II's. Both motors are being freshened and I could change cams now if I wanted to. I found the 16 x 24 3 blades on ebay and was wondering if going with a larger (pitch and dia) prop would help me get out of the hole any better, right now it is a PITA, I am trying to find 4 blades but the prices that I am seeing for them are not in my budget.

If you are having a hard time getting out of the hole with the 21's you'll never get out with the 24's