MerCruiser 350 Magnum EFI GEN+ Alfa One, Operation And Maintenance Manual

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CA284
Power Trim
Power Trim allows the operator to adjust the drive angle, while under-
way, to provide the ideal boat angle for varying load and water condi-
tions. Also, the Power Trim system “Trailering” feature allows the op-
erator to raise and lower the drive unit for trailering, beaching,
launching and low speed (below 1200 RPM engine speed), shallow
water operation.
! CAUTION
Never trim the drive unit UP/OUT using TRAILER switch while
boat is underway at engine speeds above 1200 RPM. Use ex-
treme caution when operating with drive unit raised. Severe
damage to the drive unit may result if unit is raised beyond the
gimbal ring support flanges at engine speeds above 1200 RPM.
1
In most cases, best overall performance is obtained with the drive
unit adjusted so the boat bottom will run at a 3
°
to 5
°
angle to the wa-
ter.
Trimming Drive Unit UP/OUT Can:
•
Lower the bow.
•
Generally increase top speed.
•
Increase clearance over submerged objects or a shallow bottom.
•
Cause boat to accelerate and plane off slower.
•
In excess, cause boat “porpoising” (bouncing) or propeller ventila-
tion.
•
Cause engine overheating if trimmed UP/OUT to a point where
any cooling water intake holes are above the water line.
Trimming Drive Unit DOWN/IN Can:
•
Help the boat accelerate and plane off quicker.
•
Generally improve the ride in choppy water.
•
In most cases, reduce boat speed.
•
If in excess, lower the bow of some boats to a point at which 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 steer-
ing” or “over steering” if any turn is attempted, or if a significant
wave is encountered.