Regal 42SC Owner's Manual page 130

When trimmed or in the bow down position, the bow
spray is farther forward, the wake is smaller, and positioned
further behind the vessel. Also, when trimmed you will
notice that the tachometers show an increase in rpm's.
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
Porpoising is a running condition where the bow "bounces"
up and down similar to a porpoise motion. Press "bow
down" in one-half second bursts. As the trim tabs turn,
the porpoising should recede and the vessel speed should
increase. Only a small amount of "bow down" is normally
necessary to make this change.
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Systems