Yamaha F250 LF250 - Manual (Page 43)

Operation
37
EMU27911
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 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.
NOTE:
Depending on the type of boat, the outboard
motor trim angle may have little effect on the
trim of the boat when operating.
EMU27940
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 casing from damage by collision with
obstructions, and also to reduce salt corro-
sion.
WARNING
EWM01130
● Be sure all people are clear of the out-
board motor when tilting up and down,
also be careful not to pinch any body
parts between the drive unit and engine
bracket.
● Leaking fuel is a fire hazard. If the out-
board motor will be tilted for more than
a few minutes, close the fuel cock or dis-
U6P212E0.book Page 37 Monday, June 6, 2005 4:23 PM