Diameter
- This is the measurement from the center of the propeller shaft to the
outer most point of the blade and multiplied by 2.
Pitch - This is the distance the
propeller would travel in one revolution without any slip. There will
always be a percentage of slip in the forward movement of the propeller.
Pitch is measured in inches.
Constant
Pitch
- This pitch remains the same all the way across the face of the
blade.
Progressive Pitch - This
pitch is lower at the leading edge and increase progressively across
the face of the blade.
Rake - This is the angle the blade
is attached to the hub of the propeller. Not to be confused with pitch.
Higher rake propeller blades will be angled towards the prop nut.
Cup - This is the sudden and sharp
turn up of the blade at the trailing edge of the blade face. Cup enables
the blade to grip or bite the water better. A cupped propeller will usually
turn 200-400 rpms less than an uncupped propeller of the same size.
Aluminum Propellers
vs. Stainless Steel Propellers