PROPELLERS
The propeller converts the engine’s power into the
thrust needed to propel the boat. Care and selection
of your propeller is very important to proper boat
operation. Propellers are identified by two numbers,
such as 13 x 19, and a material identification, such
as aluminum or stainless steel. In the number
sequence, the first number is the diameter of the
propeller and the second is the pitch.
Pitch is the angle of the blades expressed in
the theoretical distance a propeller travels
in each revolution. In the above example,
the pitch is 19, or each revolution of the
propeller pushes the boat 483 mm
(19 in.) through the water. A 19
pitch is considered “higher” pitched
and a 15 pitch propeller is
considered “lower” pitched.
Keep these guidelines in mind
when selecting a propeller:
●
There are many different propeller designs for specific operating
characteristics, including the number of blades, relief holes, cupping,
etc. Do not attempt to change propellers until after you have a chance
to determine your average load and individual requirements. Your
dealer is best qualified to help you select a propeller.
●
Engine RPM must be within the recommended operating range. Refer
to the engine operator’s manual.
●
Higher propeller pitch reduces: RPM, acceleration, engine noise, and
usually improves fuel economy and top speed.
●
Lower propeller pitch increases: RPM, acceleration, engine noise,
reduces fuel economy and top speed.
Scout Boats
6-6
6
Chapter 6
KC-1581
PITCH
(ONE REVOLUTION)
DIAMETER
KC-1580
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