Conditions Affecting Operation; Weight Distribution (Passengers And Gear) Inside The Boat; Bottom Of Boat; Elevation And Climate - Mercury MerCruiser Series Manual

• 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.
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.

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)

Bottom of Boat

To maintain maximum speed, ensure that the boat bottom is:
• Clean, free of barnacles and marine growth.
• Free of distortion, nearly flat where it contacts water.
• Straight and smooth, fore and aft.
Marine vegetation may accumulate when the boat is docked. This growth must be removed before operation; it may clog water
inlets and cause the engine to overheat.

Elevation and Climate

Elevation and climate changes will affect the performance of your power package. Loss of performance can be caused by:
• Higher elevations
• Higher temperatures
• Low barometric pressures
• High humidity
For you to have optimum engine performance under changing weather conditions, it is essential that the engine be propped to
allow the engine to operate at or near the top end of the specified maximum RPM range with a normal boat load during your
normal boating weather conditions.
In most cases, recommended RPM can be achieved by changing to a lower pitch propeller.

Propeller Selection

Operating the engine with the wrong propeller installed can limit power, increase fuel consumption, overheat the engine, or
cause internal powerhead damage. Choose a propeller that allows the engine to operate at the specified wide open throttle
RPM.
90-8M0117076 FEBRUARY 2018
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WARNING
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NOTICE
Section 3 - On the Water
Page 35