There are few areas of neglect of a boat that can cause more costly damage so quickly than a propeller shaft stuffing box that is throwing water around an engine room. And while surveyors have been warning boat owners about this potential costly problem for decades, we continue to see large numbers of boats where the owners seem to be unaware of this, and that this apparently common knowledge is still not so common.
To give you an idea of just how costly the failure to realize that your propeller shafts are throwing water around your engine compartment can be, consider that we recently saw a generator set mounted between two engines, where the side of the generator engine block had been corroded almost completely through. The leaking stuffing box had literally destroyed the generator. In addition to that, the battery charger, engine starter motors were damaged, along with a large number of electrical connections were corroded and caused equipment failures. All totaled, we estimated that this seemingly "minor problem" had caused upwards of $15,000 worth of damage.
All because of a stuffing box throwing water and the lack of an ounce of prevention that costs no more than $5.00 and a half hour of time.
You can add to the likely resulting damage rusted shaft/transmission couplings that will have to be cut off and replaced the next time you have to pull a shaft. That, because the bolts and couplings are so badly wasted that they no longer come apart and have to be cut. This involves a huge amount of labor plus the costs of new couplings. Figure in a few grand more for that damage.
Unfortunately, this is an all too common happening. Sometimes it's not just a failure to install splash guards over the stuffing box, but a failure to fit the guards correctly so as to contain the spray. A stuffing box, also called a packing gland, doesn't have to leak much. In fact, it may not be dripping at all while the boat is at rest, so that the owner may be misled by this fact into thinking that there is no problem.
Moreover, when you look at a stuffing box while underway at speed, you may not be able to actually see what is happening. When a shaft is rotating very fast, it can be creating a very fine mist of salt water spray. So fine that it is not visible. But if you place your palm over the stuffing box, it will come away wet. To make matters worse, your engines are ingesting that mist and severely reducing their life span.
This problem is so easily preventable, that no boat owner should fail to do it. Whether your stuffing boxes are leaking or not, or whether you have "dripless" glands installed or not, never think that the shafts cannot be throwing water.
To create an effective splash guard, the guard needs to completely surround the point where the shaft extends into the gland opening. We often see splash guards cut from a piece of hose in such a way that it only covers the top side of the shaft, which continues to throw water upward from the bottom side of the shaft, making this guard ineffective.
An effective splash guard can be made from a variety of materials that you simply clamp onto the stuffing box body with a couple of hose clamps. Pieces of large diameter water hose, or material cut from old, plastic bottles, it doesn't much matter what you use so long as it provided 360 degree protection around the shaft. The amount of coverage should be at least 4" forward on the shaft from the opening.
In most cases, it takes no more than half an hour to do the job, and can end up saving you thousands of dollars in unwanted damage.
Oh, and by the way, after you install them, don't get the idea that you never have to look that way again. There is a great deal of vibration going on in that area, so be sure to check it out occasionally to be sure your splash guards haven't slipped out of position. They often do.
David Pascoe is a second generation marine surveyor in his family who began his surveying career at age 16 as an apprentice in 1965 as the era of wooden boats was drawing to a close.
Certified by the National Association of Marine Surveyors in 1972, he has conducted over 5,000 pre purchase surveys in addition to having conducted hundreds of boating accident investigations, including fires, sinkings, hull failures and machinery failure analysis.
Over forty years of knowledge and experience are brought to bear in following books. David Pascoe is the author of:
In addition to readers in the United States, boaters and boat industry professionals worldwide from nearly 80 countries have purchased David Pascoe's books, since introduction of his first book in 2001.
In 2012, David Pascoe has retired from marine surveying business at age 65.
On November 23rd, 2018, David Pascoe has passed away at age 71.
Biography - Long version