Operation
53
EMU27912
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. 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 perfor-
mance further, and the boat may “porpoise”
(hop in the water), which could throw the op-
erator 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. Operat-
ing 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.
TIP:
Depending on the type of boat, the outboard
motor trim angle may have little effect on the
trim of the boat when operating.
EMU27944
Tilting up and down
If the engine will be stopped for some time or
if the boat is moored in shallows, the outboard
motor should be tilted up to protect the propel-
ler and lower case from damage by collision
with obstructions, and also to reduce salt cor-
rosion.
WARNING
EWM01541
Be sure all people are clear of the out-
board motor when tilting up and down.
Body parts can be crushed between the
motor and the clamp bracket when the mo-
tor is trimmed or tilted.
U6P276E0.book Page 53 Wednesday, April 1, 2009 9:44 AM
