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How to read boat propeller numbers?

Boat propellers come in various shapes, sizes, and types depending on the type of watercraft, its intended use, and the engine. These propellers are typically marked with identification numbers that tell boaters crucial information such as pitch, diameter, and rotation. Here’s:


The pitch of the propeller refers to the distance it moves or propels the boat forward with one complete revolution. It is expressed in inches, and the number is usually written on the propeller hub or blades. For example, if the propeller has a pitch of 14 inches, it means that one complete turn of the propeller will move the boat forward by 14 inches.


The diameter of the propeller is the distance measured across the entire cycle of the propeller blades. It is also often denoted in inches and is the distance from blade tip to blade tip, multiplied by two. Generally, larger diameter propellers are suitable for boats with more substantial engines.


Determining the rotation of a boat’s propeller is important for installation and safety. A right-hand propeller rotates clockwise when viewed from the stern, while a left-hand propeller rotates counterclockwise from the same perspective. The rotation direction can be determined by checking the propeller label, which usually includes an R (right-hand) or L (left-hand) designation.

Additional Information

The propeller’s identification number may also include other important information such as its spline count, blade style, and material composition. It is essential to check the owner’s manual, manufacturer specifications, or consult with a professional to determine the suitable propeller for your boat.

Reading boat propeller numbers is essential for selecting the right propeller for your boat and ensuring safe boating. Understanding the pitch, diameter, rotation direction, and additional information on the label can help prevent accidents, improve performance, and prolong the life of your boat’s propulsion system.

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