What is the best propeller to use on a 1996 15' bass boat with one motor and a force 70 hp 2 stroke motor?

Question

What is the best propeller to use on a 1996 15' bass boat with one motor and a force 70 hp 2 stroke motor?

Answer 1

I'd go with a 10x17 prop.  This is a lot of power for a 15' boat, and I think to get the best speed you can go with the 17.  If you want a good hole-shot drop down to the 15" pitch.  G

Answer 2

the prop must be determined by your engine RPM.

you need to find out what is the manufacturers recommended maximum RPM at full throttle.

Then you select the prop that lets you run at that RPM with the boat normally loaded.

Too much pitch lugs (puts too much load on) the engine, increases combustion temps, promotes carbon build up which leads to sticking rings and eventual piston failure.

Too little pitch lets you overrev the engine, with pretty much the same result.

If you're running at your target RPM with the throttle wide open gives you optimum load conditions at all throttle settings.

All else being equal, increasing one inch of prop pitch brings your RPMs down by 200, and vice versa.

General rule, cupping the blades equals about an inch of pitch.

So, the first steps are: make sure your motor is tuned up to make all the power it can, hang it where the the antiventilation plate is 1 to 2" higher than the keel, then take it out with a normal load and see what your RPM's are at WOT.