Adjusting Boat Trim; Tilting Up And Down - Yamaha F115 Owner's Manual

Operation
EMU27913

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 per-
formance further, and the boat may "por-
poise" (hop in the water), which could throw
the operator and passengers overboard.
72
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.
TIP:
Depending on the type of boat, the outboard
motor trim angle may have little effect on the
trim of the boat when operating.
EMU27936

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 lower casing from damage by
collision with obstructions, and also to re-
duce salt corrosion.
EWM00223
WARNING
Make sure that no one is near the out-
board motor when tilting the outboard
motor up or down. Otherwise, body parts
could be crushed between the outboard
motor and the clamp bracket.