The choice of a propeller is critical to your boats' performance. Propellers furnished with smaller motors are at best a compromise and may actually be detrimental to the life of your motor. Please consider the load and use to which you are putting the motor and prop accordingly. I believe that the best choice is generally "second gear" or a slightly LOWER pitch than you might otherwise select to avoid lugging the motor under load. In the case of 4 blade selection, it is important to remember that as a GENERAL rule reduce the pitch 2" from that of a 3 blade. Do not scrimp on your propeller selection. Would you put a set of 6.70 X 15 rayon cord tires on a Corvette or a Viper? Of course not. This is where "The rubber meets the road" so to speak!