14 1/2x19 on a 200hp oceanrunner at about 56-5800rpm. *I cant' remember exactly on the rpm but thats ballpark. *GPS has top speed at 49.7 kts. *She clips along pretty good. *As does my fuel tank.
Also, that was with the top down, < qtr. tank fuel, running w/tide, breeze, etc...
Hope that helps
O yeah, Alum prop.