26
Chapter 5
When trimmed or in the bow down position, the bow spray
is farther forward, the wake and rooster tail are smaller,
and positioned further behind the vessel. Also, when
trimmed you will notice that the tachometers show an
increase in rpm’s.
Using
Stern Drive Power Trim
With Trim Tabs
Adjust the
trim tabs
to achieve a planing
attitude. Use the
power trim to
position the prop
path parallel to the
water flow. At this
point the trim tabs
may need a fine
adjustment.
One advantage of
the trim tab system is that they allow trimming of the hull
while the power trim results in trimming the props.
Porpoising is a running condition where the bow “bounces”
up and down similar to a porpoise’s swimming motion.
This condition is normally caused by the trim being too
far “up” as indicated on the trim gauge. Press “bow down”
in one-half second bursts and the porpoising should recede
and the vessel speed should increase. Only a small amount
of “bow down tab” is normally necessary to make the vessel
bow actually go down.
Rectifying A List
Your vessel can use the trim tabs to
rectify a list. The trim tabs adjust the
boat’s attitude in the direction the
helm rocker switch is pushed.
If the port bow is high, push the left-
hand “bow down” direction on the
dash rocker and the port bow will
lower. If the starboard bow is high,
push the right-hand “bow down”
direction and the starboard bow is
lowered.
Porpoising
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