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S
ECTION
A. F
O
I
OREIGN
BJECT
P
A
ROPELLER
CTION
Weeds, ropes, fishing lines or nets can become
wrapped around the propeller and/or shaft, causing
vibration and loss of speed. Always stop and then
reverse the propeller after going through a weedy
area to unwrap and clear away any weeds which
may have accumulated. Although reversing will
sometimes help to unwrap lines and nets, they are
difficult to remove without hauling the boat.
Always check for loose or trailing dock lines before
getting underway.
remember that a long line may easily become
entangled with the propeller when backing down.
B. B
P
ENT
ROPELLER AND
A badly damaged or distorted propeller or shaft is
an obvious cause of vibration. Even when the
propeller appears to be perfect, make sure it has
not been pulled off-center by the propeller key.
C. E
S
NGINE AND
HAFT OUT OF
Although the shaft is properly aligned when it leaves the
factory, after transit and after the boat has been in the
water a few days, the alignment should be rechecked.
The shaft coupling is the connecting point between the
shaft and the engine and the alignment should be set at
.005 or less. Refer to SHAFTS (pg. 4.9) in this section of
this Owner's Manual.
D. C
OUPLING OUT OF
Although an extremely unlikely condition, check the
couplings if other efforts to correct the vibration fail.
Check the engine half of the coupling (with dial
indicator on the face) to see that it runs true with
the shaft coupling. Also check the coupling keys.
They must fit correctly to prevent forcing the
couplings off center.
E. E
P
H
NGINE
ART
ITTING
Engines are flexibly mounted to reduce transmission of
vibration to the hull structure. If some part of the engine,
44 Sedan Bridge (455 Sedan bridge)
4 • B
ILGE
NTERFERING WITH
When towing a dinghy,
/
S
OR
HAFT
A
LIGNMENT
T
RUE
B
S
OAT
TRUCTURE
& U
NDERWATER
such as the oil pan, reverse gear or reduction gear
housing, contacts a stringer, brace or part of the hull,
vibration will result. The flexible shaft log allows a limited
side motion of the shaft, but an excessive "whip" can
cause the shaft to strike the sides of the shaft hole or
the shaft log with resultant vibration.
F. O
P
THER
OSSIBLE
Other causes of vibration include the following:
engine out of tune, a bent rudder, a worn strut
bearing, a component of the exhaust system
vibrating against the hull or improper contact
between shaft taper and the propeller hub bore.
13. R
& R
UDDER
B
OX
The rudder is the vertical flat surface aft of the
propeller that pivots about a vertical axis and
changes the direction of the boat through the
water. The rudder stuffing box prevents water
from leaking into the boat where the rudder
post enters the hull. Spot check for leaks
before and after using your boat.
R
& R
UDDER
UDDER
(F
. 4.11.1)
IG
D
C
B
A
G
EAR
C
AUSES
S
UDDER
TUFFING
S
B
TUFFING
OX
E
F
RUDDER
A
B
HULL
JAM NUT
C
PACKING
D
E
RUDDER POST
F
RUDDER STUFFING
BOX
4.11
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