| Diameter |
Imaginary circle defined by
the blade tips as the Propeller rotates. |
| Pitch |
The distance (usually
expressed in inches) a propeller would move in one revolution in a solid
medium with no slippage. |
| Cup |
A small bend in the
trailing edge of a propeller blade. |
| Rotation |
Viewing from the stern
Right Hand propellers rotate clockwise, and Left Hand propellers rotate
counterclockwise. Many propellers
marked RH or LH on the hub. |
| Blade Tip |
Maximum reach of the blade
from the center of the hub. |
| Leading Edge |
When viewing propeller from
astern this edge is furthest away. |
| Trailing Edge |
When viewing propeller from
astern this edge is closest. |
| Hub |
Solid cylinder at the
center of the propeller bored to accommodate the shaft. |
| Bore |
Hole drilled in the center
of the hub to accommodate the shaft. |
| Keyway |
Rectangular slot cut into
the center of the hub which is used to secure the propeller to the shaft. |
| Blade Root |
Where blade attaches to
hub. |
| Blade Face |
Also called pressure side,
is the aft side of the blade (facing stern). |
| Blade Back |
Also called Suction Side,
is the forward side of the blade (facing bow). |
| Radius |
Distance from the axis of
rotation to the blade tip. |
| Local Pitch |
Amount of pitch on a blade
in a specified segment of a radius. |
| Rake |
The fore or aft slant of a
blade with respect to a line perpendicular to the propeller axis of rotation. |
| Negative Rake |
Blade slants toward bow. |
| Positive Rake |
Blade slants toward stern. |
| Skew |
The transverse sweeping of
a blade such that viewing the blade from fore or aft shows an asymmetrical
shape. |
| 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. |
| Constant Pitch Propeller |
Propeller blades have the
same value of pitch at each cylindrical section from blade root to tip. |
| Controllable Pitch
Propeller |
Propeller blades mount
separately on the hub, each on one axis of rotation, allowing a change of
pitch in the blades. |
| Progressive Pitch
Propeller |
Propeller blades have
sections designed with varying values
of local pitch on the Blade Face. |
| Variable Pitch Propeller |
Propeller blades designed
to have different values of pitch at different radius sections from blade
root to blade tip. |
