I have an 225 hp Optimax ( 2007 ) on a 22.5 feet boat.
I have test with a 17" pitch propeller and it runs 50.5 mph at 6,000 rpm ( discarded, too much rpm ),
Then i use a 19" pitch it runs 49 mph at 5,650 rpm ( good rpm but low speed, don't understand )
My last test was with a 21" and it...