There are many factors that must be considered by boating enthusiasts when choosing boat propellers. This is because all props are not the same. Some are designed for high performance while others are made for general purpose use. Boat owners should therefore buy the most suitable propellers for their boats.
The most durable propeller material is stainless steel. Props made from this material are normally used in high performance boating. The most common pitch size for these propellers is 23 inches but there are some companies that make props with higher pitch than this. Generally, you can find stainless steel props selling at prices starting from 200 dollars upwards. Aluminum propellers are also very common. They are normally used for general applications. The biggest pitch for these props is 23 inches and their prices start from 180 dollars.
Factors To Consider When Choosing A Propeller
Every boat engine has an RPM upper limit. This rating is normally indicated on the owner manual or somewhere in the engine. At full throttle, the right propeller should allow the engine to rotate at speeds of 150 to 200 revolutions per minute within the engine’s RPM upper limit. There are two factors that affect performance, pitch and diameter. Pitch is the distance a boat will move when the propeller makes one full rotation; assuming there is no slippage. Diameter is the distance across the circle made by rotating propeller blades. These parameters are normally indicated on the propeller itself. For instance, a 13×19 rating on a prop simply means that its diameter is thirteen inches while the pitch is 19 inches.
Relationship between Pitch and RPM
At full throttle, the speed of the engine should be just within the 150 to 200 RPM bracket of the upper limit. If the speed is far below this tolerance, a propeller with a lower pitch should be used. On the other hand, if engine speed exceeds the upper limit, a propeller with a higher pitch should be used. This is because pitch and engine speed, at full throttle, are inversely proportional to each other. If you over-pitch, a boat will pick up speed very fast but you may not be able to control it with ease.