It is a sealing piece that prevents water from entering through the propeller shaft. There are several models, and while some provide a perfect seal, for others it is normal that they let a few drops of water pass through.
Tow is the fibrous component produced, among other things, during the combing of flax or hemp. Wing Lock Type Stainless Steel Cable Ties
In the old navy, tow was mainly made from hemp and the lint of old rope and was used for smothering (filling the gaps in a hull between planks with tow for sealing) and caulking (filling the gaps in a hull between planks with tarred tow to make it watertight).
With the advent of shaft-line motor vessels, a problem of water ingress arose and the gland, previously soaked, was the only known seal.
Many boats are equipped with a shaft line motorization and the stuffing box is a must. This is the case for some inboard motorboats, but also for most sailboats also equipped with inboard. The propeller shaft line is composed of : a cake for connecting the propeller shaft to the inverter and thus to the motor a gland packing for the sealing a stern tube for guiding and holding the propeller shaft a hydrolube ring which will limit the vibrations of the propeller in rotation and cool the shaft by letting the water pass through the stern tube.
Flat Cable Clip There are two main families of cable glands: