PYI Shaft Seal

We just installed a new PYI on our boat. The original was around 10 years old, which is when they recommend replacement. It probably would have lasted much longer but for one very scary incident. The hose clamps on the stern tube end had worked loose and the bellows rotated along with the graphite ring. This caused the cooling line to wrap around the shaft, cutting off the flow of the cooling water, which resulted in a major overheat. This happened at the end of a several day long trip as we put the boat up on plane to blow out the engine (we had been running around 8-9 knots for several days, and this happened at 14 knots). By the time we noticed the smell of burning plastic and opened up the hatch to the shaft log there was smoke pouring out. Took four gallons of water poured on the shaft and seal before it stopped steaming to the point where I could touch it. Lesson learned - MAKE SURE YOU CHECK THOSE HOSE CLAMPS AS REGULAR MAINTENANCE.

As to the strength and quality of the unit, I was actually able to get it back in place and readjusted to the the point where we were only getting a few drips at low RPM. This allowed us to get back to the dock. I replaced the whole unit with the help of a friend while the boat was in the water. I don't recommend this, but the bilge pump had no problem keeping up while we swapped parts (about an hour), plus we had another pump standing by. I also had to replace the inner cutless bearing becuase the rubber had melted from the heat. So far no problems. Checking the bellows clamps is a noted maintenance item, as is readjusting the ring if it starts to leak at speed, so I blame this one on myself. Worst part is I spent hours in the ER tightening every engine clamp when we bought the boat last year, but never got around to checking the clamps on the shaft seal.

With low speed shafts like many trawlers...a tradition stuffing box with the new Teflon packing can be fine tuned to only have an ooze of water and it will stay cool...generally after an 8 hour run I bet less than a cup may have come in the boat...sometimes I'm not sure any came in but the shaft is moist and cool.

I used rad hose clamps for several years after taking on LOTS of water twice but switched to a shaft zinc (clamp style) flat on the ends. Have had no trouble but after reading all this I'm tempted to install 2 hose clamps in addition.

But if I actually think of this as that big a threat I probably should pull out the PSS and go back to a regular stuffing box. Think'in

....wonder what Dashew uses.

IntervaleII said:

Another option for those who are considering installing a dripless shaft seal is Tides Marine, shaft seals. You are able to put an extra seal on the shaft which allows you to change out the seal if it starts to leak while in the water.
Just another option

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Early this year during a haul-out, I changed out my old PSS seal for a Tides Marine unit. Expensive, but excellent reputation. My PSS was plain old worn out and I couldn't get it to stop misting. Once back in the water, the Tides Marine unit wouldn't seal. The Yard was perplexed since they had installed so many of the units and it never failed them before. I mic'd the shaft and it was barely 2000ths out in the seal area. After adjusting to no avail, I yanked the boat again and put back the PSS seal. Frankly, I prefer the Tides Marine design, and it's true....the water gush of the PSS unit does concern me, but it's done a good job for years, so... One thing though....I ran into the owner of Tides Marine at the Miami Show and he gave me his card...good for a free seal on the next haul-out. He thinks the metal spring must have been missing from the inside of the lip seal. Possible.

skidgear said:

....wonder what Dashew uses.

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Probably whatever he wants...but does it really matter????... as thousands of seasoned boaters have have millions of sea miles under their keels that either support or don't the products out there.

These days with Teflon packing...I think I get more water in the hull from the assorted leaks and condensation than I do from a conventional packing...no way I'm changing as it's as simple as it gets and the old issue of dripping is all but gone.

skidgear said:

....wonder what Dashew uses.

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Better yet, what does the USCG use on their new craft?

But if I actually think of this as that big a threat I probably should pull out the PSS and go back to a regular stuffing box. Think'in __________________

Duramax solves all the shaft seal problems with out the chance of a 5000GPH leak,