These inevitably corrode at the bottom, so you may need a mirror to check them.

Stuffing boxes are also used to seal rudder stocks that penetrate the hull below the waterline.

Its primary components are a threaded sleeve and a hollow nut through which the shaft passes.

The sleeve or sometimes the nut is filled with rings of braided square flax rope that has been heavily impregnated with wax and lubricants.

Tightening the nut compresses this packing against the shaft, forming a watertight seal while still allowing the shaft to turn.

It is not uncommon to see stuffing boxes leak at a much higher rate.

This doesnt harm the shaft or the stuffing box, but the spinning shaft will sling this excess flow all over the engine compartment, leading to rampant corrosion of the shaft coupling, the transmission housing, and everything else getting sprayed.

If your stuffing box leaks more than 8 or 10 drops a minute, it needs servicing.

Tightening the stuffing box nut a half turn is all that is required to reduce the leak, but the location of the stuffing box can render this job far more difficult than it should be.

Access can be especially challenging in boats with V-drives and in sailboats.

You can use pipe wrenches to turn the nuts, but adjustable packing nut wrenches tend to be easier to handle in confined spaces.

If the stuffing box is above a deep bilge, tie a retaining line to the wrenches before you start.

With your wrenches on both nuts, hold the adjusting nut and turn the locknut clockwise to release it.

Now turn the adjusting nut clockwise until the dripping just stops.

You do not want to twist this hose or twist the stuffing box inside the hose.

If the adjusting nut does not turn easily, use a pipe wrench on the stuffing box flange located just forward of the hose to keep the box from turning with the nut.

If the box is corroded, back off the adjusting nut several turns and wire brush the box threads bright before making the adjustment.

Give threads and nuts a heavy coat of Boeshield T-9 (or some other corrosion blocker) to avoid this problem in the future.

You can do this either with the boat underway or with the transmission engaged in forward and the boat securely tied in the slip.

With the help of a flashlight and a mirror if you need one count the drops per minute.

If you cannot make this adjustment without putting body parts or clothing in dangerous proximity to the spinning shaft, stop the engine, make the adjustment, then restart it to check the drips.

When the drip rate is one or two drops per minute, stop the engine.

Hold the adjusting nut securely so that you do not alter the setting, then tighten the locknut against it.

Before you extract yourself from your access position, carefully check the strap clamps that attach the hose to the stuffing box and to the stern tube.

Marine Stuffing Box Wrench