I have a Saltmarsh Heron that I am managing a fifty two stroke Yamaha tiller and was thinking what prop to run. I am at this time managing a SCB4R14 that I can only turn up about 4800 rpms @ 33 mph with my standard fishing load. Its a minor gradual getting out of the gap also. I was thinking what the correct prop would be to run to get my numbers up. I also have a SCB3R15 that I can turn 5200 @ 36mph but it is ate up fairly excellent from the earlier owner.