How To Choose Numbers of Blades
The choice between a three-blade and a four-blade propeller depends mostly on the desired performance characteristics of the boat. A three-blade propeller usually offers better top-speed performance in a non-surfacing piercing application, while a four-blade propeller provides better acceleration and smoother cruising operation.
Most propellers are made with three blades as a compromise for vibration, convenient size, efficiency, and cost. The efficiency difference between a two- and a three-bladed propeller is considered less significant than the vibration difference. Most of today’s production propellers are presently either three- or four-bladed.
In recent years, with the growing frequency of propellers being run at an increased height (surface piercing), four- and five-bladed propellers have become more popular. They suppress the higher level of vibration and improve acceleration by putting more blade area into the water. They can also help to make the rake more effective in lifting the bow of the boat for added speed.