Quick question about prop pitch and gear ratio

[Steve2ManyBoats]

One of my boats is a 20 Ft. Sea Ox with a console and T-top. I have a 2.5 liter Merc 200 on it that runs very strong. I have a quick question about prop pitch and gear ratio.

In terms of efficiency - both in terms of gas mileage and speed, would I be better off running a 21 pitch with a 1.875 gear ratio or say a 23 pitch on a 2.0 gear ratio lower?

What I'm asking is - for this boat in particular and in general - would a faster spinning lower pitch prop be more or less efficient than a slower spinning higher pitch prop? Would one get better mileage and the other get better cruising and top speed?

Appreciate your experiences and advice.

Steve2ManyBoats.

[Dave Strong]

You probably won't notice any real change in speed or mileage, might accelerate slightly better.

Dave

[rgsauger]

In lower prop speed applications, it's a wash. When you're turning 8 or 9k + rpm is when it starts to matter based on hydrodynamics. In your application, experiment with props and run the one that works best for ya