Thomas,
the "tube" that your shaft exits the hull is your shaft log. The
cutlass bearing(s) are usually rubber lined tubes of fiberglass or
bronze inserted into the shaft log to keep the shaft centered and
prevent damage to the log and wear on the shaft,they are grooved to
allow water to lubricate the bearing surface and are thus not a water
barrier. They are typically held in place by set screws. the stuffing
box is coupled to the shaft log at the inside end by a hose and
clamps...It is usually a bronze pipe-like device with a chambered end
and cap through which the shaft passes.around the shaft in the upper
end of the stuffing box are several "rings" of a flax or teflon
impregnated packing material. The cap is tightened down against the
"pipe" to compress the packing material between the wall of the
stuffing box and the shaft forming the water boundary(should still
allow a small amount of water to pass when running to prevent burning
up the packing) On wooden boats they often use a flanged stuffing box
on both ends of a drilled timber shaft log in lieu of cutlass bearings.
The stuffing boxes work much the same way as the packing on the shaft
of a standard gate-valve(water valve such as for your washing machine
or garden hose bib)
hope this helps...
regards,
markvictor
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