Engines; Propellers; E - 4 Propellers; Diameter - Four winns FREEDOM Owner's Manual

2. Use extreme caution while operating the engine in
confined areas such as enclosed slips or congested
piers. Operation under such conditions could easily
lead to exhaust gasses (carbon monoxide) entering
even though you may have all the hatches, windows,
doors and portholes closed.
3. Persons sleeping can be easily overcome by carbon
monoxide because they are unaware of its presence.
Sleeping while the engine is running is not recom-
mended. If persons are sleeping aboard while under-
way, those awake should monitor for carbon mon-
oxide accumulation in the cabin; especially the sleep-
ing areas.
NEVER operate the propulsion engine while ev-
eryone on-board is sleeping. Fatal carbon mon-
oxide poisoning can occur.
For additional information, refer to Section B-2 Carbon
Monoxide.
E - 3

ENGINES

Consult the Engine Owners Manual included in the
owner's packet for additional operation and maintenance
information.
E - 4

PROPELLERS

Knowledge of the propeller is most easily gained through
better understanding of the terminology used to refer to
the aspects of propeller size and performance.
NOTICE
Never run with a damaged propeller. You can
damage the engine or drive unit. Keep a spare
propeller on board.
A. Diameter
Diameter is twice the distance from the center of the prop
shaft to the extreme tip of a propeller blade. Increasing or
decreasing propeller size will have a direct bearing on the
rpm's (revolutions per minute) an engine will develop. This
is due to the greater amount of propeller blade surface in
contact with the water. See Figure E1.
Freedom™/Horizon™ Owner's Manual
B. Pitch
Pitch is a measure of helix angle, or angle of attack, of
the rotating blade. Pitch is easily understood if one imag-
ines the propeller rotating through a semisolid such as
butter or jello. The distance the propeller will travel in one
revolution is called "Pitch." Increasing or decreasing pitch
will also have a direct bearing on engine rpm's because
of the greater bite taken by the blade with each rotation.
See Figure E1.
Figure E1: Propeller Pitch & Diameter
C. Prop Slip
When traveling through water a propeller is unable to get
a complete bite because of the fluidity of water. "Prop
Slip" is usually expressed as a percent of the computed
theoretical speed. Fifteen to twenty-five percent prop slip
is common for a sport-type boat operating at cruising
speed.
Changing either diameter or pitch will have an effect on
engine speed and prop slip, and in turn, directly affect the
performance of a boat. The propeller(s) included with each
Section E
Page 2