Function

• The angle and type of the propeller you put on your outboard motor can change the performance of the boat dramatically. Some people choose propellers that get the boat out of the hole quicker, while others will opt for a propeller that gives them a higher top speed. As little as a 1-inch difference in the pitch of your propeller can mean the difference between as much as 200 RPM at maximum throttle.
  
  

Diameter

• The primary measurements of any propeller are its diameter and its pitch. On a propeller, these numbers are expressed as diameter by pitch. The diameter of the propeller you purchase for your outboard motor is generally dictated by the motor manufacturer. Only certain diameters will fit your motor. Pitch can vary. The higher the pitch of the prop, the more water it pushes with each revolution. In practical application, a higher pitch will give you a greater top speed but slower acceleration.
  
  

Types

• The two most common propeller designs are three-blade and four-blade, though five-blade propellers also exist. Popular manufacturers of outboard propellers include OMC, Mercury, Yamaha, Volvo Penta and Black Max.