Yamaha 40D, Owner'S Manual

Page: 37 / 77

Operation
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your boat and operating conditions.
NOTE:
To adjust the trim angle while the boat is
moving, use the power trim and tilt switch lo-
cated on the remote control device or tiller
handle, if equipped.
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Adjusting boat trim
When the boat is on plane, a bow-up attitude
results in less drag, greater stability and effi-
ciency. This is generally when the keel line of
the boat is up about 3 to 5 degrees. With the
bow up, the boat may have a greater tenden-
cy to steer to one side or the other. Compen-
sate for this as you steer. The trim tab can
also be adjusted to help offset this effect.
When the bow of the boat is down, it is easier
to accelerate from a standing start onto
plane.
Bow Up
Too much trim-out puts the bow of the boat
too high in the water. Performance and econ-
omy are decreased because the hull of the
boat is pushing the water and there is more
air drag. Excessive trim-out can also cause
the propeller to ventilate, which reduces per-
formance further, and the boat may “por-
poise” (hop in the water), which could throw
the operator and passengers overboard.
Bow Down
Too much trim-in causes the boat to “plow”
through the water, decreasing fuel economy
and making it hard to increase speed. Oper-
ating with excessive trim-in at higher speeds
also makes the boat unstable. Resistance at
the bow is greatly increased, heightening the
danger of “bow steering” and making opera-
tion difficult and dangerous.
NOTE:
Depending on the type of boat, the outboard
motor trim angle may have little effect on the
trim of the boat when operating.
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Tilting up and down
If the engine will be stopped for some time or
if the boat is moored in shallows, the out-
board motor should be tilted up to protect the
propeller and casing from damage by colli-
sion with obstructions, and also to reduce