Adjusting and Repacking the Shaft’s Packing Box
There are (were, when I last had anything to do with
them) several types of packing boxes (glands, or some other name) but they
usually had much in common. Their purpose is to prevent water from entering the
boat through the shaft tube. Repacking is best done with the boat out of the
water because in repacking you need to take all of the old packing out before
you put the new in. Adding a ring or two of packing can be done in the water,
but some water will come in during the process. Some new (can be old, time
wise, but unused) packing may have been aboard when you bought the boat. If so,
then the size should be what you need. If the previous owner left some packing
aboard he may have left the packing removal tool with it. This is a Tee handled
short piece of flexible cable with a short, sharp tapered “cork screw” on the
business end. The packing is a wax impregnated woven flax (in my memory) and is
square in section. Its size should be one half the difference between the
outside diameter of the shaft and the inside diameter of the packing box.
Several rings of the packing are put around the shaft (one in front of the
other, not on top of each other) and pushed inside the box, one ring at a time.
Make the rings by wrapping several turns around the shaft and cutting (on top
dead center of the shaft) to separate the rings. You will get several pieces
the right length to encircle the shaft once, with square ends (note: called
“rings” but they are not “endless rings”). Some people make the cut on an
angle, 45 degrees or so. As you push each ring into the box place the joint of
the rings at 180 degrees to each other.
Now reassemble the packing box, tightening the whole
to the point of just about stopping all the water from entering if the boat is
in the water. Otherwise, hand tighten just enough to stop an onrush of
water when launched. A drip every once in a while is good. The water cools (a
little) and lubricates the shaft. After tightening to perfection tighten the lock
nut down of the packing nut, holding the packing nut with its wrench to prevent
further tightening on the packing. If you tighten to where no water enters you
run the risk of damaging the shaft. If you repack out of the water check the
shaft to see if it is worn down. If worn slightly and the shaft is smooth it
should be OK to repack. If worn noticeably, deeply, and is rough or grooved, a
good marine machine shop can spray braze the shaft to oversized and then turn
it down to full size (if it is not too worn). A good shop will give good advice
on that.
You can check for shaft wear by taking the
stuffing box apart and sliding the loose parts forward on the shaft (hopefully
there will be enough shaft to allow that). Use a stiff wire (clothes hanger?)
to slide back and forth on the top of the shaft over the area where the packing
was. Your little finger may be a good “feeler gauge” for this operation. Note:
do this out of the water; the packing needs to be removed to do this. If this
must be done in the water take some, not all, of the stuffing out and try to
check on the shaft’s condition. Also, to slow up the steady drip you could take
out enough of the packing to add three or four rings of new packing and tighten
it enough to bring the water under control. You could also do something (maybe
a couple of pipe wrenches, one each way, but something better should be
devised) to lock the shaft in place, then tighten down on the packing until it
stops the water as a temporary way to keep the water out while you are away
from the boat. Don’t forget to remove the wrenches (or other locking mechanism)
and slacken off on the packing before going sailing—and keep and eye on the
amount of water coming in.
If you want to be free of all those "packing
problems" consider the PSS Shaft Seal. To quote the PSS people,
"The PSS Shaft Seal is a mechanical face seal that uses a self-aligning
high density carbon-graphite stator to ensure a 100% watertight seal with
proven reliability. The carbon stator is held against an O-ring seated
stainless steel collar by a tough, chemical and fuel resistant nitrile rubber
bellow. This seal will eliminate shaft wear and minimize
corrosion." I have no experience with this system, but it is the
same or similar system used in house water pumps and I've never had problems
with those. I noticed on the picture of this system that it has a small
plastic nipple present that probably requires a small diameter hose for water
to run overboard, via either the bilge pump or a thru-hull fitting. This
is to allow water circulation through the shaft bearing at the stern tube to
cool and lubricate the bearing. Without this you will have a vast wear
problem similar to that mentioned above. See www.shaftseal.com/ for
information from the manufacturer and www.fisheriessupply.com/
for one supplier and search for dripless shaft seal. Costs
around $400 but to me it's worth it. Maintenance is almost
non-existent, and the flax removal tool, packing nut wrench, and
flax need not be purchased, and there will be no packing box (overtight
flax) wear or worries.
