[Public-List] Dripless shaft seal- a cautionary tale

[Greg Bover]

Just back from a cruise to Maine shortened by a shaft seal problem. As others have opined in the past, dripless shaft seals are a nice thing, but when they fail, the failure tends to be catastrophic.
We had had a wonderful day sailing across Casco Bay and then motoring a few miles up the mouth of the Sheepscot River to Five Islands Harbor, a lovely spot with a welcoming boat club. When I turned off the engine I noticed the bilge pump running much more frequently than it ever does. After inspection of the bilge, I found that the bellows of the shaft seal had cracked where it connects to the shaft tube. A jet of water was streaming into the boat, the bilge pump running about once a minute. I took up the cockpit grating and opened the rectangular access hatch I installed last year to replace the engine mounts. Thank goodness, otherwise I would have been going in over the hot engine. I had a couple of rolls of silicone "Rescue Tape" I had bought a decade ago at a boat show and never used. The great virtue of this tape is that it sticks to itself underwater and self-amalgamates over time. I wrapped several layers around the tail end of the bellows where the crack was and reinforced the tape with three hose clamps. The jet of water was reduced to a fast drip, the bilge pump now ran every twenty minutes or so. Still, unable to trust that the bellows wouldn't crack further, we cancelled the rest of the trip, turned tail, and made a fast passage back to Cape Ann, where we quickly hauled out, as it isn't possible to fix it properly while in the water.
Now that I have read up on dripless shaft seals, I understand that the suggested life of the nitrile bellows is about five years. I've had #114 for twelve years and no idea how long before that the P.O. installed the unit. It just wasn't on my preventive maintenance list. It is now. And I have ordered more silicone tape.

Greg Bover
A-30 #114
PENSIVE FLYER
Gloucester, Mass.