WIKI -
Components
A stuffing box of a sailing boat will have a stern tube that is slightly bigger than the prop shaft. It will also have packing nut threads or a gland nut. The packing is inside the gland nut and creates the seal. The shaft is wrapped by the packing and put in the gland nut. Through tightening it onto the stern tube, the packing is compressed, creating a seal against the shaft.
[2] Creating a proper plunger alignment is critical for correct flow and a long wear life. Stuffing box components are of stainless steel, brass or other application-specific materials.
Gland
A gland is a general type of stuffing box, used to seal a rotating or reciprocating shaft against a fluid. The most common example is in the head of a tap (
faucet) where the gland is usually packed with string which has been soaked in
tallow or similar grease. The gland nut allows the packing material to be compressed to form a watertight seal and prevent water leaking up the shaft when the tap is turned on. The gland at the rotating shaft of a
centrifugal pump may be packed in a similar way and graphite grease used to accommodate continuous operation. The linear seal around the
piston rod of a double acting steam piston is also known as a gland, particularly in marine applications. Likewise the shaft of a handpump or
wind pump is sealed with a gland where the shaft exits the borehole.