Specifications

OPERATION
eng 71
EXAMPLE: An engine running at an elevation of 8,000 feet will
have over a 30% power loss while a loss of engine power on a
hot and humid day could be as much as 14%. These losses
apply to normally aspirated and supercharged engines.
Compensating for power robbing conditions:
• Switch to lower pitch propeller.
• Change gear ratio.
Some boat performance can be improved by dropping to a lower
pitch propeller, but engine performance will still remain lower. In
some cases, a gear ratio reduction may be more beneficial. To
optimize engine performance, prop the engine to allow it to
operate at or near the top end of the recommended maximum
RPM range at wide‑open throttle with a normal boat load.
Other advantages to propeller or gear ratio changes:
• Reduces the possibility of detonation
• Enhances overall reliability and durability of the engine
Setting Trim Angle While Running Engine at Idle
Speed
Submerging the exhaust relief hole on the outboard can happen
on some boats if you trim full in while running at idle speed,
resulting in, exhaust restriction, rough idle, excessive smoke,
and fouled spark plugs. If this condition exists, trim outboard up
until exhaust relief hole is out of the water.
a - Relief hole
submerged (wrong)
b - Relief hole above
waterline (correct)
Operating in Shallow Water
When operating your boat in shallow water, you can tilt the
outboard beyond the maximum trim range to prevent hitting
bottom.
a
b
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