On Thu, 19 Apr 2012 16:03:01 -0700 (PDT), Bil
wrote:

On Tuesday, April 17, 2012 10:12:05 AM UTC+10, Bruce wrote:

In passing, I always wondered what people using the so called
"dripless" shaft seals do in the event of a catastrophic failure of
the rubber flex housing? With a conventional stuffing box one can
re-pack it with old tee shirts and use Crisco for a lube but what
happens, way out there in the briny, when that red rubber hose bursts?

The usual answer is to avoid catastrophic failure with routine maintenance.

For example, PYI Inc (the manufacturer of the Packless Shaft Seal fitted on my shaft) recommends replacing the rubber bellows every 6 years.

Failures have been reported to be associated with poor engine room practices, including allowing oils and greases to contact the rubber bellows.

Especially in warm tropical water with high organic content, the stator of the PSS can stick to the rotor. Rotating the shaft by hand to break the stiction reduces stress on the bellows.

Cheers

Bil

Ah yes. Periodic Preventative Maintenance. The trouble is that while I
know a lot of people who talk about it I know even more who have
suffered major problems. Guys who's propeller and shaft suddenly part
company with the boat; guys who can't wind up the jib because the
upper bearing disintegrated; guys who's throttle or shift cable fall
off because the little cotter pin broke. I even knew a guy who's
warning buzzer kept going off; probably faulty wiring, he thought. It
turned you that it was low oil pressure warning..... because the oil
level was so low.

And that is to ignore those who's exhaust elbow falls off, the exhaust
hose that splits (No, I don't now how old it was... came with the
boat, I guess) and the sheave at the top of the mast falls off because
the shaft was worn through (Oh! you are supposed to grease that?).

While I give maintenance its due I also try to built things that when
all else fails can be repaired with an apron string and some duct
tape.
--
Cheers,

Bruce