Adjusting Boat Trim - Yamaha F4 Owner's Manual

2. Tilt the outboard motor up, and then re-
move the trim rod from the clamp brack-
et.
1
1. Trim rod
3. Change the position of the trim rod in di-
rection "A" to raise the bow ("trim-out").
Change the position of the trim rod in di-
rection "B" to lower the bow ("trim-in").
TIP:
The outboard motor trim angle changes ap-
proximately 4 degrees when the trim rod po-
sition is changed by 1 hole.
4. Make test runs with the outboard motor
set at different trim angles to find the po-
sition that works best for your boat and
operating conditions.
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.
A
B
ZMU06755
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.
Operation
47