Mercury Racing 500R Operation And Maintenance Manual page 62

If the engine or drive is trimmed out too far, the propeller may lose its hold
on the water, fast V‑bottom boats may start to walk from side to side (chine
walking), steering torque will increase in the opposite direction to that when
trimmed in, and getting on plane may be difficult or labored. Porpoising of the
boat may also occur.
Engine or drive trimmed out (bow too high); porpoising
Boat Loading and Trim
Under normal loading and operating conditions while on plane, the boat bottom
is roughly parallel to the surface of the water. Changing the loading of the
boat will not change the trim angle as previously defined, but it will change the
running attitude of the boat with respect to the surface of the water. Adding
weight toward the stern of the boat will cause the bow to rise. Similarly, adding
weight toward the bow of the boat will cause the bow to lower.
Changing the trim angle can compensate for a change in the running attitude of
the boat. Increasing the trim angle will raise the bow of the boat, compensating
for bow heavy loading. Decreasing the trim angle will lower the bow of the boat,
compensating for stern heavy loading.
Choosing an Active Trim Profile
If Active Trim is configured properly, the normal setting for running on plane
will be profile 2, 3, or 4. This allows the operator the flexibility to change
the trim angle to compensate for variations in boat loading or other operating
conditions. Selecting a higher number profile will raise the bow and selecting a
lower number profile will lower the bow.
Use the preceding descriptions of trim in and trim out to help determine
whether or not your boat is trimmed properly (refer to How Trim Affects Boat
Operation). In general, this means you can increase the trim profile until the
bow begins to porpoise (rise and fall), and then back off one level.
ACTIVE TRIM RED STATUS LIGHT
A flashing red light can indicate different things, depending on if
ACTIVE
it is a single or a double flash sequence.
TRIM
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FEATURES AND CONTROLS
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