Three blades are less efficient than two. Following blade is in the turbulence of the preceding blade by 1/3 more time. There was a guy in about '46/7 that made a single blade prop for a 65hp Continental, counterbalanced at the hub with weights.
It was a much more efficient prop but it wore out main bearings at an alarming rate due to the asymetrical thrust. I like three baldes much better than two if I have enough power to compensate for a little less efficiency.