Boat Propellers: Terminology

Sante Marine Propeller has everything you need regarding boat propellers! We don’t just sell propellers, we repair & re-pitch them as well as providing skeg & cavitation plate repair and shaft straightening. We are here to make sure you spend less time out of the water and more time on it having fun!

For your reference, here are some of the general terms and also a few technical ones in the propeller business.

National Marine Propeller Association

Propeller Term

What it means...

Diameter

 The diameter of the imaginary circle scribed by the blade tips as the propeller rotates.

Radius

The distance from the axis of rotation to the blade tip. The radius multiplied by two is equal to the diameter.

Blade Face

Pressure Side, Pitch Side. Aft side of the blade surface facing the stern.

Blade Back

Suction Side. Forward side of the blade surface facing the bow.

Leading Edge

The edge of the propeller blade adjacent to the forward end of the hub. When viewing the propeller from astern, this edge is furthest away. The leading edge leads into the flow when providing forward thrust

Trailing Edge

The edge of the propeller adjacent to the aft end of the hub. When viewing the propeller from astern, this edge is closest The trailing edge retreats from the flow when providing forward thrust.

Blade Number

Equal to the number of blades on the propeller.

Blade Tip

Maximum reach of the blade from the center of the hub. Separates the leading and trailing edges.

Hub

Solid cylinder located at the center of the propeller. Bored to accommodate the engine shaft. Hub shapes include cylindrical, conical, radius & barreled.

Blade Root

Fillet area. The region of transition from the blade surfaces and edges to the hub periphery. The area where the blade attaches to the hub.

Rotation

When viewed from the stern (facing forward): Right-hand propellers rotate clock wise to provide forward thrust. Left-hand propellers rotate counter-clockwise to provide forward thrust.