Power Trim And Tilt - Mercury 40 4-Stroke Manual

Power Trim and Tilt

Your outboard has a trim/tilt control called power trim. This enables the operator to easily adjust the
position of the outboard by pressing the trim switch. Moving the outboard in closer to the boat transom
is called trimming in or down. Moving the outboard further away from the boat transom is called trimming
out or up. The term trim generally refers to the adjustment of the outboard within the first 20° range of
travel. This is the range used while operating your boat on plane. The term tilt is generally used when
referring to adjusting the outboard further up out of the water. With the engine turned off, the outboard
can be tilted out of the water. At low idle speed, the outboard can also be tilted up past the trim range to
permit, for example, shallow water operation.
a
b
a - Remote control trim switch
b - Panel mount trim switch
POWER TRIM OPERATION
With most boats, operating around the middle of the trim range will give satisfactory results. However,
to take full advantage of the trimming capability there may be times when you choose to trim your
outboard all the way in or out. Along with an improvement in some performance aspects comes a greater
responsibility for the operator, and this is being aware of some potential control hazards.
The most significant control hazard is a pull or torque that is felt on the steering wheel or tiller handle.
This steering torque results from the outboard trimmed so that the propeller shaft is not parallel to the
water surface.
Trimming the outboard beyond a neutral steering condition may result in a pull on the steering wheel
or tiller handle and loss of boat control. Maintain control of the boat if trimming beyond a neutral
steering condition.
Consider the following lists carefully.
Trimming in or down can:
• Lower the bow
• Result in quicker planing off, especially with a heavy load or a stern heavy boat
• Generally improve the ride in choppy water
• Increase steering torque or pull to the right (with the normal right hand rotation propeller)
• In excess can lower the bow of some boats to a point where they begin to plow with their bow in
the water while on plane. This can result in an unexpected turn in either direction (called bow
steering or over-steering) if any turn is attempted, or if a significant wave is encountered.
FEATURES & CONTROLS
WARNING
!
c
d
c - Tilt range of travel
d - Trim range of travel
28
28520