PROPELLER SELECTION
Refer
to
Propeller Hardware Installation
on
p.
44 before installing propeller.
The correct propeller, under normal load condi-
tions, will allow the engine to
run
near the mid-
point of the
RPM
operating range at full throttle.
Refer to TECHNICAL DATA
on
p.
16.
100%
1 "-.90%
80%
70%
60%
5OC}6
40%
30%
-
6--··
2---
0
1. Percentage
of
horsepower (kw)
2.
Engine RPM
3.
Horsepower curve
4. Full throttle operating range
\---3
-7-
DR1261
5. Midpoint
of
full throttle operating range, horse-
power rating
in
kilowatts (kw))
6. Engine is overloaded at full throttle
7. Engine
is
overspeeding at full throttle
A CAUTION A
Selection
of
the
wrong
propeller
could
reduce engine service life,
affect
boat
per-
formance,
or
cause
serious
damage
to
the
powerhead.
INSTALLATION AND PREDELIVERY
PROPELLER
SELECTION
Procedure
The propeller selection process
is
very important
to the engine's service life and to boat perfor-
mance. Proceed
carefully and thoroughly while
considering the following points:
• During the engine break-in period,
run
the out-
board at wide-open
throttle for only brief periods
of time to check
full-throttle RPM.
• Use
an
accurate tachometer to determine the
engine's
full-throttle
RPM
while testing various
propellers.
• Select
a propeller that suits the customer's
application and allows the engine to
run
near
the midpoint of the
full-throttle operating range
when the boat has a
normal load
in
it.
Refer to
TECHNICAL DATA
on
p.
16.
•
To
compensate for changes
in
boat loading, the
engine's
full-throttle
RPM
must
be
verified peri-
odically.
IMPORTANT: If the propeller blades have too
much pitch, the engine
is
operating below its nor-
mal range at full throttle, power
is
being lost, and
powerhead damage could occur. If the propeller
blades
have too little pitch, the engine
is
operating
above its normal range at full throttle and damage
from overspeeding
could occur.
A WARNING A
When
servicing
the propeller,
always
shift
the
outboard
to
NEUTRAL,
turn
the
key
switch
OFF,
and
twist
and remove all
spark
plug
leads
so
the
engine
cannot
be started
accidentally.
43
I
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