Trim Tab Adjustment; Boat Performance; Test Instructions - Mercury 45 Jet 50-55 Service Manual

Trim Tab Adjustment

1. Check trim tab position as follows:
a. Operate boat at the speed at which it would nor-
mally be operated.
b. If the boat pulls to the right (starboard), the trailing
edge of trim tab must be moved to the right. If the
boat pulls to the left (port), the trailing edge of trim
tab must be moved to the left.
2. If necessary, adjust trim tab as follows:
a. Shift outboard control into neutral and turn ignition
key to "Off" position.
b. Loosen bolt (c) and trim tab (b).
c. If boat pulls to the left, adjust trailing edge of trim
tab to the left. If boat pulls to the right, adjust trailing
edge of trim tab to the right.
d. Tighten trim tab bolt securely.
e. Operate boat per "Check trim tab position as
follows," to check trim tab setting. If necessary
readjust trim tab.
a
b
c
a - Anti-Ventilation Plate
b - Adjustable Trim Tab
c - Bolt
1-12 - GENERAL INFORMATION and SPECIFICATIONS

Boat Performance

TEST INSTRUCTIONS

WARNING
!
A tight grip on the steering wheel/tiller handle is
always advisable and is required when accelerating,
decelerating or when trimming the boat. On models
with Power Trim, upon reaching cruising speed, the
outboard should be trimmed to obtain a balanced
steering condition. While trimming, steering loads will
vary and will pull in one direction until a balanced
condition has been attained. If the outboard is trimmed
past the balanced steering condition, the steering
wheel/tiller handle then will have a tendency to pull in
the opposite direction. Excessive trimming past the
balanced steering position will result in increased
steering loads and, in most boat applications, a
decrease in performance.
CAUTION
!
When trimming boat with dual outboards, both out-
boards should be at approximately the same tilt angle
and be tilted out (up) simultaneously (to prevent boat
from veering side-to-side) until desired boat attitude is
achieved. Outboards can then be trimmed individually
to precisely adjust boat trim angle and pitch.
1. With boat in water, trim the outboard(s) (trim button in
remote control handle) so that the decal on the side of
cowl is horizontal. This is a typical average setting that
should give reasonable acceleration and top speed.
2. Go for a short familiarization ride at various throttle and
trim settings BEFORE starting testing.
NOTE: Instruments should be read with eye directly in front
to eliminate any error in reading the instruments.
3. When making either top speed or acceleration runs,
best accuracy will be obtained by running with or
against any wind. Side winds require driving in a con-
stant turn to keep the boat moving straight-ahead. If
winds are 10 MPH (16 km/hr) or greater, it is suggested
that all acceleration runs be made downwind.
4. The top speed WOT (wide-open-throttle) test should
be done with the boat normally loaded (to duplicate
actual running conditions). Operate boat in gear at
50553
WOT and check RPM. Engine RPM must be within the
recommended full throttle RPM range (listed in the
Operation and Maintenance Manual).
NOTE: When performing an acceleration test, it is
recommended that a stop watch be used to improve testing
accuracy. A wrist watch with a second hand may also be
substituted.
90-817643R1 DECEMBER 1996