Inboard propeller seal information
Subject: Inboard Propeller Shaft Seals From: barefootr@aol.com (Barefootr) Subject: Suffing Boxes - Shaft Seals Date: 11 Sep 1994 10:46:01 -0400 <<>> Leaking Stuffing boxes are a common sight. General stuffing boxes are made up of basically string wrapped tightly around the shaft, and then compressed via the nylon lock nut. It is *essential* that there is some "shaftseal" 83 lines, 4622 characters up of basically string wrapped tightly around the shaft, and then compressed via the nylon lock nut. It is *essential* that there is some water flow through the seal during operation. This should only amount to approximately 2-4 *drops* per minute, into the boat hull. As most know, to change this, just pull out the cotter pin on the locking nut, turn to the next avialable alignment hole, and replace the cotter pin. Depending on use, you might do this 1 or 2 times per season. See Aricle below ****** Stuffing Boxes & PSS Shaft Seals The most overlooked aspect of your tournament tow boat is the stuffing box. Most people either don't know what to look for, or don't take the time to constantly adjust the packing nut to obtain the proper drip rate per minute. The worst nightmare of any boat owner is coming back to a boat that has taken the deep six plunge. This situation has happened more than once, and can be prevented for a small investment. The reason that a situation like this occurs is because of the stress that the stuffing box takes over a period of time. Every time your boat goes over 14 mph a vacuum is created in the shaft log.This creates several problems. First, the packing material, whether it is rope or nylon, has a stainless steel drive shaft turning on an average of 4000 rpm's without any lubrication or cooling. Second, the rubber hose expands and contracts as the boat goes above and below 14 mph. The hose will eventually become soft, and one day burst. The other problem that is occurring in the bilge, is the water that above and below 14 mph. The hose will eventually become soft, and one day burst. The other problem that is occurring in the bilge, is the water that leaks in the boat is heating, and then evaporating to corrode parts in the engine. The most important element in a stuffing box is maintenance. All of these problems can be eliminated by switching to a shaft seal. Shaft seals are designed to prevent water coming into the boat through the shaft log. Do they really work? The answer is, you get what you pay for. I say that, because there are some seals that work perfectly and some that aren't much better than a stuffing box. There are two types of seals. The face seal and the lip seal. On the face seal, sealing is taking place between the face of a rotor and a stationary flange. The rotor turns with the shaft and the compression pressure of the bellows creates the seal against the flange. The advantage of this type of seal is that there are no wearing surfaces, so the seal can last a very long time. The other type of seal is called a lip seal. The seal on this type is made with a nitrile (rubber) o-ring. If something should damage the o-ring, then the sealing surface is ruined. In either instance, because shaft seals are more expensive, you need to be careful which one you purchase. Here are a few questions to ask when shopping for a shaft seal: 1) What materials are used to manufacture the seal? (This is important to determine the life of the seal) 2) How long has the seal been manufactured? (To give you an idea if the seal is proven or new to the market) 3) What happens if the water supply is cut off? (This is very important. Some seals will destroy themselves without a water supply. 4) How well does the seal handle vibration or misalignment? (This will cause unnecessary stress on the seal and shaft if there is no flexibility to the seal) Have fun with your boat, don't spend ski time worrying about it! The more maintenance-free you make your boat, the less time you'll spend adjusting the stuffing box. There are many ways to upgrade your boat, so take advantage of the technology available. Consider switching to a shaft seal, it is worth the investment. **Mike Waldin, Sr. is the Marketing Director for A.R.E. Manufacturing, in Oregon. He has written drivetrain articles for WATERSKI magazine, and done extensive research on shaft seals.