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AQUILA OPERATING MANUAL
NW Explorations
3B5: Trim Tabs
The boat is fitted with a set of Bennett Trim Tabs. These are wide “flaps” attached to the aft end of the boat,
under the swim step at the trailing edge of the hull, operated hydraulically under the control of the skipper by
rocker switches with indicators at each helm station.
At low speeds, up to approximately six knots, the tabs do little, and should be left in the “Bow Up” position (see
below). But at speeds over this range, the tabs begin to take effect and will help the operator lower the bow for
more efficient cruising.
The best way to adjust the tabs is to lower them while watching the “Speed” indicator to get the highest speed
at a given throttle setting by adjusting “Bow Down”. If the tabs are “Bow Down” too much, the steering will get
mushy and speed may drop off a little, and the tabs should be adjusted “Bow Up” a little. Note that it will take
time to make these adjustments; when the buttons are depressed, they need to be held 2-5 seconds each
time for change to be felt and observed (the best way to see the effect of the tabs is by the knot meter and by
observing the height of the bow relative to the horizon, most easily seen from the lower helm station).
Because the trim tabs are so large, THEY MUST BE IN THE FULLY-BOW-UP POSITION WHENEVER THE
BOAT IS TO BE OPERATED IN REVERSE, otherwise the great water forces against the tabs may damage
them severely, even tearing them off the hull!