How many hp would it take to push an aluminum hull 31' long by 12' wide with
a 9 degree deadrise weighing 15000 lbs approx 35 mph with a sterndrive. I
know there are many variables but I just want a ballpark idea. Would 300 hp
do it or would you need 1000hp.

and this would be easily accomplished with a couple of fairbanks morse 15
cyl models going though a step 1:8 gear turning a couple of 36X36 wheels
;-)

another Brian
tongue also in the usual place