While the exact course of action will be determined to some extent by the boat and type of shaft stuffing box or seal you have, the first thing you'll want to do is stop or at least slow the rate of water coming into the boat. Bad as it may be with the boat tied to the dock, when the boat is offshore and possibly miles from a safe haven, it can be devastating. The inrush of water is so severe that no bilge pump can keep up with the flow. Stuffing box failure when a boat is left unattended at the dock will almost always result in a sinking. Do it with the boat on the hard, especially if this is your first time. Perhaps the most popular incorporates Teflon, which increases wear resistance while reducing friction on the shaft.Īlthough it's possible to change the packing with the boat in the water, we recommend against that. While packing material is traditionally made of flax, recently it's being made out of other materials. Any larger, and you'll probably be looking at 3/8 inch. As a general rule, shafts up to about 11/2 inches require quarter-inch packing. Packing comes in different sizes depending on the size of the shaft the larger the shaft, the bigger the packing required. When this happens, it's time to change the packing material, which can be purchased from retailers such as Defender or West Marine. Over time the packing will wear, and no amount of adjustment will prevent more water than desired from entering the boat. If you can't leave your hand on the fitting after the engine has run, that's an indication that it's been overtightened and you need to loosen the compression sleeve just a little. The water acts as a lubricant and prevents the packing from overheating while the shaft is turning.Īfter you make any adjustments, monitor the stuffing box to ensure all is well at no point should a packing box get too hot to touch. The stuffing box must never be overtightened as it's designed to leak a little. To do this, loosen the locknut (depending on type, this may be the nut threaded around the body or lock washers on the bolts), tighten the adjustment sleeve a little, then retighten the locknut. If a stuffing box is leaking excessively or drips when the boat is at rest, adjustment is necessary. There should be no dripping when the boat is at rest and the shaft is not spinning. When properly adjusted, stuffing boxes are designed to "leak" slightly at two to three drops per minute while the engine is running and the shaft is turning. As the packing compression sleeve is tightened, the flax is slightly squeezed outward toward the shaft, lightly gripping the shaft and preventing water from entering the boat. Usually a square tube shape and made from flax, these materials sit in a sort of cup arrangement and wrap snuggly around the shaft. Under the compression sleeve are three or more rounds of packing material. The second basic type, like that on my boat and to which I'll primarily refer in this article, consists of the body that is attached to the hose and into which the packing is stuffed, and a compression sleeve that compresses the stuffing by tightening the nuts on the bolts protruding from the body. Perhaps the most common type consists of a stuffing box body attached to a special heavy-duty hose (attached to the shaft gland), a compression sleeve into which the stuffing is packed and which screws over the body, and a locking nut that locks the compression sleeve into place. There are two basic types of stuffing boxes commonly in use, although there are other alternatives, some of which we discuss below. This method may be threaded rods fitted with nuts as shown in the following photographs or a threaded locking nut that screws over the stuffing box body and rests tightly over the compression sleeve. There are three main components to a traditional stuffing box: the stuffing box body, the compression sleeve, and some method of locking the compression sleeve in place. If your boat has inboard power, chances are it has a stuffing box that allows a propeller shaft to penetrate the hull below the waterline without letting water in and flooding the boat.
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