Stuffing Box And Stern Tube
I've always thought the stuffing box should be called a stuffing round, because it has very little in common with a box. Nevertheless, it does serve an important role. The stuffing box allows the shaft to pass through the hull and spin, while keeping seawater out. It does this by packing successive sections, usually three, of waxed flax line around the shaft and holding them there under slight pressure with a packing nut. This line, or packing, is able to perform this task by being lubricated, like the cutless, with water. The seawater keeps the packing cool and slippery. If the packing nut is overtightened, it will prevent enough cooling water from reaching the packing within, melting the wax, which then runs out of the packing. This will allow water to pass through the packing and into the boat. If allowed to continue, the packing will disintegrate eventually and the drip will become a run. I am of the "let it drip" school of thought. It is better for a stuffing box to drip too much rather than too little. If it drips too much, it can always be tightened. However, if overtightened, damage occurs rather quickly and a second chance will not be forthcoming. Even though I am an advocate of keeping the bilge as dry as possible to avoid all sorts of other problems, I make an exception here. There are many theories concerning the rate of drip when the shaft is stationary. For the low rpms that a sailing vessel's auxiliary is likely to turn, one drip every five to eight seconds should be safe. For gasoline-powered vessels running at higher rpms a drip every three seconds would be safer.