It is very important to use the proper pitch propeller on your 50-horsepower Mercury outboard. Too low a pitch makes it difficult to accelerate and get the boat on-plane or pull skiers, and will also cause the engine to over-rev. Too high a pitch will give great acceleration and pulling power but severely reduce speed and make it difficult to keep on-plane. Always replace a damaged propeller -- they easily become unbalanced and cause vibration that can damage the lower unit.
Describe the motor type, horsepower and weight and type of boat when purchasing a new propeller, or use the same number pitch propeller as the one that came off.
Remove the cotter pin from the propeller drive shaft using wire cutters. Remove the large shaft nut using an adjustable wrench.
Remove the large washer behind the nut and pull the propeller straight off. Grease the propeller shaft prior to installing the new propeller.
Slide the propeller onto the shaft followed by the washer and nut. Tighten the shaft nut with the adjustable wrench. Insert the cotter pin and bend the ends with the wire cutters to prevent the cotter pin from coming out.
