Propeller Selection - Mercury 1.7 MI Manual

SECTION 3
CE464

Propeller Selection

The installed propeller must allow the engine to run at the Rated Engine rpm at WOT
to avoid engine damage. Using a propeller that causes the engine to operate below
the Rated Engine rpm can cause piston and/or valve damage (even if the engine is
not operated at WOT). Conversely, using a propeller that allows engine to operate
above the specified Rated Engine rpm can increase fuel consumption and wear and
will not allow engine to produce its rated horsepower.
It is the responsibility of the boat manufacturer or the selling dealer, or both, to equip the
power package with the correct propellers.
IMPORTANT: The engines covered in this manual are equipped with a governor
device that limits engine rpm. Be sure that propeller being used does not allow
engine to run excessively against the governor, as a significant loss in performance
will result.
NOTE: Use an accurate service tachometer to verify rpm.
Select a propeller that will allow the engine power package to operate at the Rated Engine
rpm with a full load on board.
If full throttle operation is below the Rated Engine rpm, the propeller must be changed to
prevent loss of performance and possible engine damage. On the other hand, operating an
engine above the Rated Engine rpm will cause higher than normal wear and/or damage.
After initial propeller selection, the following common problems may require that the
propeller be resized:
• Warmer weather and greater humidity cause an rpm loss.
• Operating in a higher elevation causes an rpm loss.
• Operating with a damaged propeller or dirty boat bottom causes an rpm loss.
• Operating with increased load (additional passengers, pulling skiers).
CMD-3967823 / 90-865237030 OCTOBER 2003
INDEX
CAUTION
ON THE WATER
Page 37