NOTES ON PACKING BOXES

[Clyde A. Phillips]

Adjusting and Repacking the Shaft’s Packing Box

 

There are (were, when I last had anything to do with them) several types of packing boxes (glands, or some other name) but they usually had much in common. Their purpose is to prevent water from entering the boat through the shaft tube. Repacking is best done with the boat out of the water because in repacking you need to take all of the old packing out before you put the new in. Adding a ring or two of packing can be done in the water, but some water will come in during the process. Some new (can be old, time wise, but unused) packing may have been aboard when you bought the boat. If so, then the size should be what you need. If the previous owner left some packing aboard he may have left the packing removal tool with it. This is a Tee handled short piece of flexible cable with a short, sharp tapered “cork screw” on the business end. The packing is a wax impregnated woven flax (in my memory) and is square in section. Its size should be one half the difference between the outside diameter of the shaft and the inside diameter of the packing box. Several rings of the packing are put around the shaft (one in front of the other, not on top of each other) and pushed inside the box, one ring at a time. Make the rings by wrapping several turns around the shaft and cutting (on top dead center of the shaft) to separate the rings. You will get several pieces the right length to encircle the shaft once, with square ends (note: called “rings” but they are not “endless rings”). Some people make the cut on an angle, 45 degrees or so. As you push each ring into the box place the joint of the rings at 180 degrees to each other.

 

Now reassemble the packing box, tightening the whole to the point of just about stopping all the water from entering. A drip every once in a while is good. The water cools (a little) and lubricates the shaft. After tightening to perfection tighten the lock nut down of the packing nut, holding the packing nut with it wrench to prevent further tightening on the packing. If you tighten to where no water enters you run the risk of damaging the shaft. If you repack out of the water check the shaft to see if it is worn down. If worn slightly and the shaft is smooth it should be OK to repack. If worn noticeably, deeply, and is rough or grooved, a good marine machine shop can spray braze the shaft to oversized and then turn it down to full size (if it is not too worn). A good shop will give good advice on that.

 

You can check of shaft wear by taking the stuffing box apart and sliding the loose parts forward on the shaft (hopefully there will be enough shaft to allow that). Use a stiff wire (clothes hanger?) to slide back and forth on the top of the shaft over the area where the packing was. Your little finger may be a good “feeler gauge” for this operation. Note: do this out of the water; the packing needs to be removed to do this. If this must be done in the water take some, not all, of the stuffing out and try to check on the shaft’s condition. Also, to slow up the steady drip you could take out enough of the packing to add three or four rings of new packing and tighten it enough to bring the water under control. You could also do something (maybe a couple of pipe wrenches, one each way, but something better should be devised) to lock the shaft in place, then tighten down on the packing until it stops the water as a temporary way to keep the water out while you are away from the boat. Don’t forget to remove the wrenches (or other locking mechanism) and slacken off on the packing before going sailing—and keep and eye on the amount of water coming in.

 

[bob mitchell]

   Just happen to have some of that old stuff handy, along with some new. (see photo)