Yacht

In the unlikely event of a complete loss of packing flax, a number of onboard
items can be substituted in an emergency. An oily cloth will do, or greasy
length of rope. Maybe even beef jerky, although I’ve never had the occasion.
to drive a donut-shaped spacer into the
packing, pressing it between the shaft and
the stern tube to affect a seal.
Because rotational friction can generate heat
and eventually damage the shaft, a small
amount of water is required to infiltrate the
packing for lubrication. Typically five to ten
drops per minute should seep through to
ensure good lubrication for flax, a little less
for Teflon.
The simple beauty of this arrangement is that
the packing nut can be infinitely adjusted as
the flax gradually wears down. In the
unlikely event of a complete loss of packing
flax (and similar lack of foresight to carry
spares), a number of onboard items can be
substituted in an emergency. An oily cloth
will do, or greasy length of rope. Maybe
even beef jerky, although I’ve never had the
occasion.
Rigid stuffing boxes are simple and reliable,
but they can transmit vibration through the
hull and are sensitive to any misalignment of
the propeller shaft. Flexible stuffing boxes
complicate things incrementally by separating
the stuffing box and stern tube with a
short length of five-ply underwater hose.
59
flax facts
The square rope that’s
stuffed into the stern tube
around the shaft is usually
made of greased flax, one of
the oldest fiber crops in the
world. Flax has been used
to produce linen for 5,000
years.
Stronger and less elastic
than cotton fiber, the good
stuff is used for linen and
lace while you get the coarse
grades to keep the sea out of
your schooner.
Flax fans are quick to point
out that this stuff is no relation
to the New Zealand
Flax, as the Kiwi kind is not
used for nearly as many industrial
purposes.
Flax packing often comes in
2-foot (60cm) lengths and in
a range of widths to suit a
given shaft log’s concentric
offset from the shaft it seals.
classicyachtmag.com