Compression packing is rigorously tested to ensure effective sealing in valves, pumps, agitators, and other rotary equipment.
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 "box" is a cylindrical assembly, typically of bronze, comprising a sleeve threaded on one end to accept adjusting and locking nuts.
A special purpose heavy-duty rubber hose attaches the stuffing box to a stern tube, also called a shaft log, that projects inward from the hull.
A sound stuffing box installation is critical to safety because failure can admit a catastrophic volume of water into the boat.
A traditional variety of shaft packing comprises a square cross-section rope made of flax or hemp impregnated with wax and lubricants.