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

[Mike Lehman]

The old bronze stuffing box is more reliable and when teflon packing is
installed properly it can be tighten to a no-drip seal...i check mine
frequently to make sure it doesn't get hot. I've heard stories, like yours,
about sudden failures with bellows and would also worry about freezing in
the winter with water trapped inside the bellows causing premature
failure.  Good to hear you took fast action to prevent sinking.

On Sun, Aug 7, 2022, 12:48 PM Greg Bover via Public-List <
public-list at lists.alberg30.org> wrote:

> 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 th
>  e 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.
>
>
>
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