Westerbeke 50 User Manual

The coupling must not only transmit the power of the engine to
turn the shaft, but must also transmit the thrust either ahead or
astern from the shaft to the thrust bear ing which is built into the
reduction gear housing of the engine. This coupling is very carefully
machined for accurate fit.
For all engine models, a propeller half-coupling, bored to shaft
size for the specific order, is supplied. The coupling either has a
keyway with set screws or is of the clamping type.
The forward end of the propeller shaft has a long straight keyway.
Any burrs should be removed from the shaft end. The coupling should
be a light drive fit on the shaft and the shaft should not have to be
scraped down or filed in order to get a fit. It is important that
the key be properly fitted both to the shaft and the coupling. The
key should fit the side of the keyway very closely, but should not
touch the top of the keyway in the hub of the coupling.
If it seems difficult to drive the coupling over the shaft, the
coupling can be expanded by heating in a pail of boiling water. The
face of the propeller coupling must be exactly perpendicular to the
centerline or axis of the propeller shaft.
PROPELLER
The type and size of propeller varies with the gear ratio and must
be selected to fit the application based upon boat tests. To utilize
the full power of the engine, and to achieve ideal loading conditions,
it is desirable to use a propeller which will permit the engine to
reach its full rated speed at full throttle under normal load.
ALIGNMENT OF ENGINE
The engine must be properly and exactly aligned with the propeller
shaft. No matter what material is used to build a boat it will be
found to be flexible to some extent and the boat hull will change its
shape to a greater extent than is usually realized when it is launched
and operated in the water. It is therefore very important to check
the engine alignment at frequent intervals and to correct any errors
when they may appear.
Misalignment between the engine and the propeller shaft is the
cause of troubles which are blamed often on other causes. It will
create excessive bearing wear, rapid shaft wear and will, in many
cases, reduce the life of the hull by loosening the hull fastenings.
A bent propeller shaft will have exactly the same effect and it is
therefore necessary that the propeller shaft itself be perfectly
straight.
One particularly annoying result of misalignment may be leakage of
transmission oil through the rear oil seal. Check to make sure that
alignment is within the limits prescribed.
The engine should be moved around on the bed and supported on the
screw-jacks or shims until the two halves of the couplings can be
brought together without using force and so that the flanges meet
evenly all around. It is best not to drill the foundation for the
foundation bolts until the approximate alignment has been accurately
determined.
Never attempt a final alignment with the boat on land. The 'boat
should be in the water and have had an opportunity to assume its final
water form. It is best to do the alignment with the fuel and water
tanks about half full and all the usual equipment on board and after
the main mast has been stepped and final rigging has been
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Westerbeke 50 Specifications

General

Brand	Westerbeke
Model	50
Category	Engine
Language	English