Yamaha F4, Owner'S Manual

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3-3
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Overpowering a boat may cause severe
instability. Do not install an outboard
motor with more horsepower than the
maximum rating on the capacity plate of
the boat. If the boat does not have a
capacity plate, consult the boat manufac-
turer.
EMU01298
Mounting Height
To run your boat at optimum efficiency,
the water-resistance (drag) of the boat
and outboard motor must be made as lit-
tle as possible. The mounting-height of
the outboard motor greatly affects the
water-resistance. If the mounting-height
is too high, cavitation tends to occur, thus
reducing the propulsion; and if the pro-
peller tips cut the air, the engine speed
will rise abnormally and cause the engine
to overheat. If the mounting-height is too
low, the water-resistance will increase
and thereby reduce engine efficiency.
Mount the engine so that the anti-cavita-
tion plate is between the bottom of the
boat and a level 25 mm (1 in.) below it.
NOTE:
8
The optimum mounting height of the
outboard motor is affected by the
boat/motor combination and the
desired use. Test runs at different
heights can help determine the opti-
mum mounting height.
8
Refer to the section “TRIMMING OUT-
BOARD MOTOR” for instructions on
setting the trim angle of the outboard.
104013
0~25mm
(0~1in.)