Power Trim - General Information; Description; Trimming Characteristics - Mercury Optimax 115 Service Manual

Power Trim - General Information

Description

The Power Trim System consists of an electric motor, pressurized fluid reservoir, pump,
tilt cylinder, and two trim rams.
The remote control (or trim panel) has switches that trim the outboard "Up" or "Down" and
tilt the engine for "Trailering". The outboard can be trimmed and tilted under power or
when the outboard is not running.

Trimming Characteristics

NOTE: Because hull designs react differently in varying water conditions, varying the trim
position will often improve the ride and boat handling. When trimming from a mid-trim
position (with outboard trim tab in a straight fore and aft position), expect the following:
TRIMMING OUTBOARD "UP" (OUT):
Excessive trim "Out" may reduce the stability of some high speed hulls. To cor-
rect instability, reduce the power gradually and trim the outboard "In" slightly be-
fore resuming high speed operation. A rapid reduction in power will result in a
sudden change of steering torque and may cause additional boat instability.
Will lift boat bow, increasing top speed.
Transfers steering torque harder to port (left) on installations below 23 in. (584.2 mm) tran-
som height.
Increases gearcase clearance over submerged objects.
Excess trim can cause "porpoising" and/or ventilation.
Excessive outboard trim angle will result in insufficient water supply causing
water pump and/or powerhead overheating damage. Insure water level is above
water intake holes whenever outboard is running.
The "Up" circuit actuates the up solenoid (under outboard cowl) and closes the motor cir-
cuit. The electric motor drives the pump, forcing fluid thru passageways into the up side
of the trim cylinders.
The trim cylinders position the outboard at the desired trim angle in the 20 degree maxi-
mum trim range. The system will not allow the outboard to be trimmed above the 20 de-
gree trim range as long as the engine RPM is above approximately 2000 RPM.
The outboard can be trimmed above the 20 degree maximum trim angle (for shallow wa-
ter operation, etc.), by keeping the engine RPM below 2000. If the RPM increases over
2000, propeller thrust (if propeller is deep enough) will cause the trim system to return the
outboard to the 20 degree maximum trim position.
90-855347R1 JANUARY 1999
WARNING
WARNING
POWER TRIM
Page 5B-7