Using both switches to lower both tabs in balanced
(evenly port and starboard fashion) will lower the bow,
when on a plane, if the rear of the boat is loaded. As
before use only short bursts to move the trim tabs.
When running at a cruising speed the trim tabs should
be fully raised (upward position) unless the aft section of
your boat is loaded.
In a following sea, or an inlet the best maneuverability
can be achieved with a high bow attitude.
You should also raise the trim tabs when your boat is
below planing speed or at rest. When you back your
boat out of a slip, the drag from a tab still lowered will
pull your boat to that side and you will not be able to
back straight out of the slip. Raising the tabs also
protects the rams from marine growth because they are
retracted into the cylinder. The trim tabs are deactivated
by turning off the ignition.
A properly trimmed boat:
• Operates at a correct running attitude of between 3
and 6 degree angle to the water. (Slightly raised bow)
• Reduces drag and increases fuel economy
• Preserves good forward visibility and increases safety
WARNING
! !
Use short bursts to move your trim tabs. Holding
the switches to long could cause sudden steering
problems.
Port Trim Tab
Trim Tab Ram
Figure 6.7
6.3 Trim Tabs
The trim tabs are two flat plates, hinged below the water
line on the transom at the rear and are raised or low-
ered hydraulically by using the rocker switches located
at the helm.
The trim tabs are used to adjust the sideways listing of
the boat due to uneven loading, a strong crosswind, or
propeller torque. The twisting effect of propeller torque
is especially pronounced when running the engine at a
high horsepower output. To correct the listing, adjust the
trim tabs to level the boat. When the boat is level right
to left, the steering effort will be the same for port and
starboard turns.
Lower the trim tabs on the listing side by pushing the
top half of the rocker switch in short bursts, until the cor-
rect trim is reached.
Illustrated example of the steering system
Figure 6.8
Seal
Steering Ram
Rudder Port
Rudder
Packing Nut
Upper Rudder Bearing
Safety Locking Collar
Flex Nut
Tiller Arm
Mainship 34 Trawler Single & Twin • Underwater Gear
6.5
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