Drive Unit Impact Protection; Operating With Low Water Inlets In Shallow Water; Conditions Affecting Operation; Weight Distribution (Passengers And Gear) Inside The Boat - Mercury MerCruiser 4.3 TKS User Manual

Section 3 - On The Water

Drive Unit Impact Protection

The power trim hydraulic system is designed to provide impact protection for the sterndrive
unit. If a submerged object is struck while the boat is moving forward, the hydraulic system
will cushion the kickup of the sterndrive unit as it clears the object, reducing damage to the
unit. After the sterndrive unit has cleared the object, the hydraulic system allows the
sterndrive unit to return to its original operating position, preventing loss of steering control
and engine overspeed.
Use extreme caution when operating in shallow water or where underwater objects are
known to be present. No impact protection is provided in reverse; use extreme care to
prevent striking submerged objects while operating in reverse.
IMPORTANT: Impact protection system cannot be designed to ensure total protection from
impact damage under all conditions.

Operating with Low Water Inlets in Shallow Water

Operating in shallow water can cause severe engine damage due to clogged water inlets.
Ensure that the water inlets on the gearcase do not ingest sand, silt, or other debris, which
can restrict or stop cooling water supply to the engine.
Extreme care should be exercised when operating a boat equipped with low water inlets
while maneuvering in shallow water. Also, avoid beaching a boat with the engine operating.

Conditions Affecting Operation

Weight Distribution (Passengers and Gear) Inside the Boat

Shifting weight to rear (stern):
• Generally increases speed and engine RPM
• Causes bow to bounce in choppy water
• Increases danger of following wave splashing into the boat when coming off plane
• At extremes, can cause the boat to porpoise
Shifting weight to front (bow):
• Improves ease of planing
• Improves rough water ride
• At extremes, can cause the boat to veer back and forth (bow steer)

The Bottom of the Boat

To maintain maximum speed, the boat bottom should be:
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a - Low Water Inlets
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90-899883179 OCTOBER 2007