Changed to three blade this fall
Have a 2QM15 Yanmar 14 h.p. on a '80 hunter 33. This Fall I put on a smaller 13X11 3 blade replacing the original 14X12 2 blade. In doing this the engine RPM's increased 500 revolutions from 1,900 to 2,400 RPM - in neutral the engine runs at 2,800 RPM. The boat now runs a knot faster at 6.5+ kts. And the whole drive train is much smoother and quieter. If you can find a smaller 3 blade prop, give it a try. I wish I had made this change years ago. You also may be interested in the link below discussing the advantages of a 3 blade prop.
Have a 2QM15 Yanmar 14 h.p. on a '80 hunter 33. This Fall I put on a smaller 13X11 3 blade replacing the original 14X12 2 blade. In doing this the engine RPM's increased 500 revolutions from 1,900 to 2,400 RPM - in neutral the engine runs at 2,800 RPM. The boat now runs a knot faster at 6.5+ kts. And the whole drive train is much smoother and quieter. If you can find a smaller 3 blade prop, give it a try. I wish I had made this change years ago. You also may be interested in the link below discussing the advantages of a 3 blade prop.