318 prop size

i have a 1969 revelcraft and was wondering if anyone knew the correct prop size i was givin the boat and it will not get out of its own way its a 24ft with 318 thanks

 

Need to know some details: approx. HP, Boat weight, and trans. gear ratio would help.
"Can't get out of it's own way"
For starters - Does it throw a Big wake? Does it have a Tachometer? If so, What does it read wide open?

 

sorry was not even thinking

its 24ft i would say3500lb and a estimated 250horsepower it has velvet drive one to one and the wake is not more than expected it seems like at 3/4 throttle its same speed as wot.I was told this boat was fast from the previous owners friend the old owner passed away and not sure if someone changed props before i got it. i almost positive its not the prop that came with boat and motor thanks alot

 

I suspect the 318 power is probably slightly less, probably 220HP. With a total dispacement of 3500lb, max speed should be about 37 mph @ 4200rpm using a 13 x 11, 3 bladed prop.
If speed dosn't change as rpm increases, this could be caused by either driveline slippage (transmission, prop attachement) or an undersized prop.
If rpm doesn't change with increased throttle, your prop may be oversized or motor adjustments - timing etc.