Section 3 - On the Water
90-8M0074347
eng
OCTOBER 2012
Page 45
There is another less common hazardous result from allowing your boat to launch off of a wave or wake. If the bow of your boat
pitches down far enough while airborne, upon water contact it may penetrate under the water surface and submarine for an
instant. This will bring the boat nearly to a stop in an instant and can send the occupants flying forward. The boat may also veer
sharply to one side.
Impact with Underwater Hazards
Reduce speed and proceed with caution whenever you're driving a boat in shallow water or in areas where the waters are
suspected of having underwater obstacles that could be struck by the underwater drive components, rudder, or the boat
bottom.
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IMPORTANT: The most important thing you can do to help reduce injury or impact damage from striking a floating or
underwater object is control the boat speed. Under these conditions, boat speed should be kept to a maximum speed of
24–40 km/h (15–25 mph).
Striking a floating/underwater object may result in an infinite number of situations. Some of these situations could result in the
following:
•
The boat could move suddenly in a new direction. Such a sharp change in direction or turn can cause occupants to be
thrown out of their seats or out of the boat.
•
A rapid reduction in speed. This will cause occupants to be thrown forward, even out of the boat.
•
Impact damage to the underwater drive components, rudder, and/or boat.
Keep in mind, one of the most important things you can do to help reduce injury or impact damage in these situations is control
the boat speed. Boat speed should be kept to a minimum planing speed when driving in waters known to have underwater
obstacles.
After striking a submerged object, stop the engine as soon as possible and inspect the drive system for any broken or loose
parts. If damage is present or suspected, the power package should be taken to an authorized Mercury MerCruiser dealer for a
thorough inspection and necessary repair.
The boat should be checked for hull fractures, transom fractures, and water leaks.
Operating with damaged underwater drive components, rudder, or boat bottom could cause additional damage to other parts of
the power package, or could affect control of the boat. If continued operation is necessary, do so at greatly reduced speeds.
!
WARNING
Operating a boat or engine with impact damage can result in product damage, serious injury, or death. If the vessel
experiences any form of impact, have an authorized Mercury Marine dealer inspect and repair the vessel or power package.
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.
Conditions Affecting Operation
Weight Distribution (Passengers and Gear) Inside the Boat
Shifting weight to rear (stern):
•
Generally increases speed and engine RPM
