Computer Tuned Propellers • Marine Hardware

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 center of the hub.

Bore

Hole drilled in the center of the hub to accommodate the shaft.

Cup

A small bend in the trailing edge of a propeller blade.

Diameter

Imaginary circle defined by the blade tips as the Propeller rotates.

Hub

Solid cylinder at the center of the propeller bored to accommodate the shaft.

Keyway

Rectangular slot cut into the center of the hub which is used to secure the propeller to the shaft.

Leading Edge

When viewing propeller from astern this edge is furthest away.

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. Many 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.

Local Pitch

Amount of pitch on a blade in a specified segment of a radius.

Negative Rake

Blade slants toward bow.

Pitch

The distance (usually expressed in inches) a propeller would move in one revolution in a solid medium with no slippage.

Positive Rake

Blade slants toward stern.

Propeller - Constant Pitch

Propeller blades have the same value of pitch at each cylindrical section from blade root to tip.

Propeller - Controllable Pitch

Propeller blades mount separately on the hub, each on one axis of rotation, allowing a change of pitch in the blades.

Propeller - Fixed Pitch

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

Propeller - Progressive Pitch

Propeller blades have sections designed with varying values of local pitch on the Blade Face.

Propeller - Variable Pitch

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

Glossary of Common Propeller Terms