Every once in a while, I will get asked about propellers. This is always a fun topic to revisit when ever I am asked the question.
The number of blades equals more torque (thrust); so a 3-blade prop will have a higher top speed than props with 4 or more blades. More blades equals more hauling power or "umph!" on the low end.
Propeller pitch is the distance the prop would move forward in one rotation. Think of a 8/32, 1/4-20 screw; they have 32 threads / 20 threads (or times around) per inch.
You want the prop pitch to match your engine’s WOT (wide open throttle; with full load found in the engine or vessel manufacturer’s specs).
If the pitch is on the low side, your engine could exceed its suggested WOT RPM and cause engine damage; A pitch too high could put undue stress on the prop system and shorten your the life of gear case components.
You should find something that is middle of the road. For most vessels and their operators, I would recommend a 3-blade prop with a higher pitch if they want more "umph" at low speeds. But when you get "umph" at low, you loose top-end speed; it is a give an take.
Typically 2 inches of prop pitch equates to about 400 RPM off your WOT.
Stainless Steel props are about 3 times more expensive; but stainless are stronger, made thinner and can still keep their shape so you don't loose performance at higher RPM.
Good luck on your endeavors; prop sizing is kind of a black art. I hope the info I provided at least helps in your final determination.
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