|Perfection in Every Rotation
3, 4, or 5 blades?
Three blade propellers are old technology, they are not very efficient, they cavitate often and
have very poor throttle response.
Four blade propellers started to become popular in the late 90’s. The fourth blade configuration
gives the average boat less vibration, good holeshot, minimal cavitation, and noticeable throttle
Five blade propellers are quickly becoming the propellers of the new millennium. The extra
blade allows the propeller to work with little vibration. Five blade propellers provide exceptional
thrust when planing, immediate throttle response, limited cavitation and increased handling and
Cavitation is the formation of vapor bubbles of flowing water, this phenomenon allowing the
pressure of the water to fall below the vapor pressure creating intense friction. Cavitation is not a
good thing for propellers. This drop in pressure causes the propeller to become glowing hot
burning through the metal.
The pitch of the propeller is measured by the angle of the blade attached to the hub.
Theoretically, for every single rotation the propeller should move forward one inch for every inch
of pitch. (i.e. a 19 pitch propeller should move forward 19” for every complete rotation).
The propellers rake is the angle of the blades attached to the hub from the center of the propeller
out. High rake propellers tend want to suck the back of the boat down producing more lift in the
bow. Low rake takes a more screw effect pushing forward.
Rotation (Right hand & Left hand)
The majority of single engine boats are equipped with a right hand rotating propeller. Looking at
the rear of the propeller, a right hand propeller turns clockwise while a left hand propeller turns
The diameter of the propeller is the measurement from the exact center of the propeller to the
furthest outer portion of the blade then multiplied by two. This inch measurement is usually
identified first followed by the amount of pitch (i.e. 14 ¼ x 19).
Parts of the propeller
C. Leading Edge
D. Trailing Edge
F. Inner Hub