Glossary of Propeller Terms

Blade Back: Also called suction side, is the forward side of the blade (facing bow)

Blade Face:  Also called pressure side, is the aft side of the blade (facing stern)

Blade Root: Where blade attaches to hub

Blade Tip: Maximum reach of the blade from the centre of the hub

Bore: Hole drilled in the centre of the hub to accommodate the shaft

Constant Pitch propeller: Propeller blades have the same value of pitch at each cylindrical section from blade root to tip

Cup: A small bend in the trailing edge of a propeller blade

Diameter:  Imaginary circle defined by the blade tips as the propeller rotates

Feathering: The blades of a propeller means to increase their angle of pitch by turning the blades to be parallel to the water flow. This minimizes drag from a stopped propeller

Fixed Pitch Propeller: A propeller on which the blades are permanently mounted to the hub not allowing a change in propeller pitch without mechanical intervention

Hub: Solid cylinder at the centre of the propeller bored to accommodate the shaft

Leading Edge: When viewing propeller from astern this edge is furthest away

Local Pitch: Amount of pitch on a blade in a specified segment of a radius

Negative Rake: Blade slants toward bow

Pitch: The distance a propeller would move in one revolution in a solid medium with no slippage

Positive Rake: Blade slants toward the stern

Progressive Pitch Propeller: Propeller blades have sections designed with varying values of local pitch on the blade face

Radius: Distance from the axis of rotation to the blade tip

Rake: The fore or aft slant of a blade with respect to a line perpendicular to the propeller axis of rotation

Rotation: Viewing from the stern Right Hand propellers rotate clockwise, and Left Hand propellers rotate counter clockwise.  A lot of propellers marked RH or LH on the hub

Skew: The transverse sweeping of a blade such that viewing the blade from fore or aft shows an asymmetrical shape

Trailing Edge: When viewing propeller from astern this edge is closest

Variable Pitch Propeller: Propeller blades designed to have different values of pitch at different radius sections from blade root to blade tip