Yamaha DE-DHT, Stern Drive Service Manual

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GEN
INFO
E
PROPELLERS
PROPELLERS
Propellers
As the propeller turns, water is pushed down
and back, creating a positive pressure on the
face of the blade. At the same time, a nega-
tive pressure is produced on the back of the
blade, thus sucking water to it. The positive
and negative pressures cause the boat to
move forward.
The propeller size indicates the propeller di-
ameter, pitch and type or style.
The pitch of a propeller is the distance the
propeller will move forward in one complete
revolution. (This is similar to the pitch of a
screw as it moves into a hole.)
The pitch indicated by the propeller size is a
theoretical or designed pitch. The actual for-
ward motion on each revolution is less than
the theoretical pitch. The difference is known
as the “slip” of the propeller.
Water is a fluid which gives way a little un-
der the pressure of the blades. A 10 % to 15 %
slip is considered acceptable.
Propeller Selection
Because of the many designs and different
materials used, it is necessary to select the
right propeller for the boat’s specific use. A
boat can be used for various uses such as
skiing, cruising, fishing, racing, towing, etc.
Different designs affect the boat and engine
differently. Depending on the propeller de-
sign, the speed, acceleration, engine life, fuel
economy, and boating and steering qualities
can be changed to fit the particular needs of
the boat by changing propellers.
The material the propeller is made of and
where the boat is used, for example; in riv-
ers, seas, shallows, rock-bound waters, high
mineral waters, etc. are also important. Alu-
minium propellers are economical, have
good strength, good corrosion resistance and
are easily repaired. Stainless steel propellers
have tremendous strength and superb cor-
rosion resistance.
Whatever the purpose of the boat, always
make it a habit to carry spare propellers and
hand tools. In case of heavy propeller dam-
age, you will be able to rely on the spare pro-
peller to power you to a nearby port.
Below is a list of Yamaha propellers avail-
able through your dealer.
Position No. of Blades Diameter (in.) Pitch (in.) Material Part Number
F 3 15 19 Stainless Steel
F
↑ ↑
20
↑
F ↑ ↑ 21 ↑
F
↑ ↑
22
↑
6U4-45942-00-98
F
↑ ↑
23
↑
6U4-45946-00-98
F
↑ ↑
24
↑
6U4-45951-00-98
F
↑ ↑
26
↑
6U4-45955-00-98
F ↑ ↑ 28 ↑ 6U4-45959-00-98
R
↑ ↑
19
↑
R
↑ ↑
20
↑
R
↑ ↑
21
↑
R
↑ ↑
22
↑
6U4-45944-00-98
R ↑ ↑ 23 ↑ 6U4-45948-00-98
R
↑ ↑
24
↑
6U4-45953-00-98
R
↑ ↑
26
↑
6U4-45957-00-98
R
↑ ↑
28
↑
6U4-45961-00-98
F: Front, Counterclockwise Rotation
R: Rear, Clockwise Rotation
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