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Take A Stand With Your Packing Gland
 “You should have one drop of water
every 10 seconds, all the time.” “No, you should
have one drop when the shaft is still, and 10 drops
every 60 seconds while the shaft is moving.” “Wait a
minute, I read no drops while the shaft is still,
and 5 drops at high rpm's.” Confusing isn't it? It
seems every boat owner has an opinion, and that's
because every boat owner wants a dry bilge.
Unfortunately, if a dry bilge is what you desire,
you better buy oars.
Leakage is necessary to cool the
stuffing box and reduce the wear. There are three
conditions that will shorten the life of any packing
gland. The first is excessive heat, usually caused
by over tightening the gland nut. To control heat
generated by the friction between the shaft and the
packing gland, a small amount of leakage provides
lubrication and cools the packing gland. Now for the
answer to the how-many-drops question. The best way
to ensure you have enough water leaking through the
gland, is to place the back of your hand against the
stuffing box while the shaft is turning. If the
temperature is uncomfortable, it means it is too
hot. Loosen the gland nut to increase leakage until
the stuffing box is comfortable to the touch.
The second condition that will
shorten the life of your packing material is a
sideways movement while the shaft is spinning. If
you observe a wobbling motion, measure the amount by
clamping an object, like a screw driver, so that the
tip is touching the shaft. Spin the shaft and
measure the gap. If it exceeds .003 of an inch, you
probably have a misaligned engine, warped shaft or a
worn thrust bushing. The sideways motion of the
shaft will cause excess wear of the gland and will
allow water to pass freely through the gland.
The packing gland will need
replacement when your feet get wet upon entering the
gangway or you no longer can control the flow of
water leaking past the gland by tightening the
stuffing box nut. Hopefully it's the latter you deal
with first. Never add new packing material to old.
The old packing gland material will lose its
lubrication over a period of time. Dirt and grit may
also be present, causing rapid wear to your shaft.
Replacement of a propeller shaft costs well over
$200.00 verses packing gland material costing
approximately $3.00.
It is preferable to replace the
packing material when your vessel is out of the
water, but if you can no longer control the leakage
and don't want to haul your boat out, you can stop
the water from entering by putting Play-Doh or putty
into some kitchen plastic wrap and rolling it into a
cigar shape. Dive under the boat and jam the plastic
plug around the shaft, forcing it up the shaft tube.
This will slow the leakage while you replace the
packing. Don't forget to remove the plastic plug,
without water for lubrication the new packing
material will burn up.
Some of the older stuffing box
assemblies have a locking nut to lock the gland nut
in place. Corrosion and salt-water build-up will
sometimes seize the lock nut to the gland nut. Use a
generous amount of penetrating oil and wait a few
minutes for the oil to penetrate deep into the
threads. With a hammer, tap lightly around the
stuffing box to loosen up the corrosion. The newer
stuffing box assemblies have a gland nut and a gland
follower. They also might need penetrating oil to
help in removal. Once removed, clean all threads and
parts with a wire brush to remove corrosion and
water build-up. Do not wire brush the shaft; use
fine 320-grit sandpaper to clean the shaft surface.
Remove the old packing materiel with a packing
extractor. Make sure you have removed all of the old
packing material. A bent coat hanger can also be
used as a packing extractor...>>Next
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