Dripless shaft seal owners beware.

[er9]

i guess this is probably geared more towards my fellow inexperienced sailors who are new to owning a sailboat and may not have tons of experience yet.

i came back to the boat last night after being away for a few days to discover my bilge full of sea water. i thought maybe it was my heat exchanger leaking from the zinc bolt i installed last time i was on the boat. i quickly dismissed it because it was a lot of water.

immediately dove into the engine compartment to find an uncomfortable amount of water dripping from the dripless shaft seal between the carbon ring and the stainless ring. apparently sea water had slowly worked its way between the two and salt crystals began to build up and seperate them.

i have been working on my engine for 6-8 months so the engine hasn't been started in a long time. i started the engine this week when i completed some of the repairs but never put the boat in gear so the shaft hasn't had a chance to spin in 6-8 months. apparently because i hadn't in so long the sealing surface between the carbon stator and the stainless ring began to corrode or have salt/debris get between them. enough to cause a nice leak.

the fix was simply to start the engine and put it in gear for 20-30 mins in my slip to wear/clean that sealing surface. its now drip free again.

so if you have a dripless seal it might be worth turning on the engine and putting it in gear once in a while as well, especially if you expect to not be able to get back to or take the boat out for a while...or if you plan to start doing some engine work where the boat may not be started again for quite some time. run it in gear for a while before you start to tear the engine apart.

i do have an older drip less seal and im not sure if there are newer versions that prevent this sort of thing? i'd be interested in hearing any advice or recommendations if the do exist.

[GILow]

From that description I wonder if you have enough compression on the seal. It would be worth checking against the specs.

[er9]

Originally Posted by GILow

From that description I wonder if you have enough compression on the seal. It would be worth checking against the specs.

thanks...thats a good question? i guess i should try to find out what type it is and check. I can confirm that when i burp the seal the sea water does come out under a fair amount of pressure. it sprays out. i dont know though if thats any indication of the correct amount of compression though. it has been trouble free for the past three years but we used to take the boat out regularly before i started the engine work.

[GILow]

Pressure is simply a product of the depth below the waterline that the seal is situated. The make of seal does not change that.

My type is a PSS and the compression pressure is about what you’d expect, kinda firm, not particularly high or low. But yeah, the water comes out in quite a spray when I burp it.

It certainly sounds odd to me. I’ve thought about it a bit more and I wondered if maybe something small like a bit of seaweed might have somehow become trapped between the faces to allow that sort of seepage. My high school chemistry tells me salt crystals would have been washed out faster than they could form. I have trouble imagining them building up and causing a leak.

Oh, and sorry if you know this already, but just in case, most of these seals require that you replace the grub screws if you loosen them or reset the seal on the shaft, so do make sure you have fresh grub screws on hand if you do find you have to move the seal to adjust the compression.

I also fit a shaft anode in front of the seal as a fail-safe if the seal disk locking grub screws fail.

[wingless]

Originally Posted by er9

i came back to the boat last night after being away for a few days to discover my bilge full of sea water.

Doesn't the boat have automatic bilge pump(s) that would conceal this low ingress dripping?

If those pump(s) / switches are not operating properly, then those problems should be immediately corrected.

[ArmyDaveNY]

I would contact the manufacturer and see what they say. Perhaps they have seen this before.


Good luck with it.

[Scaramanga F25]

I just do not trust this type of seal. I never have had a problem with the traditional stuffing box type in 41 years. You can even repack in the water.

[Valmika]

Also a warning to new DSS Owners. When I got my first boat with one I was told they never need to be serviced. It lasted four years before it starting leaking. When I replaced it I found out I was supposed to lube it at least once a year with a small plastic tool that goes around the propshaft (from inside the boat) with grease on it. Since then I have never had an issue.
The tool is just a small circle piece of plastic that you load some grease on and shove into the inboard end of your DSS


http://www.cruisersforum.com/forums/...ls-126730.html

[170122]

Good information, I just did it and my leak stopped..

Originally Posted by er9

i guess this is probably geared more towards my fellow inexperienced sailors who are new to owning a sailboat and may not have tons of experience yet.

i came back to the boat last night after being away for a few days to discover my bilge full of sea water. i thought maybe it was my heat exchanger leaking from the zinc bolt i installed last time i was on the boat. i quickly dismissed it because it was a lot of water.

immediately dove into the engine compartment to find an uncomfortable amount of water dripping from the dripless shaft seal between the carbon ring and the stainless ring. apparently sea water had slowly worked its way between the two and salt crystals began to build up and seperate them.

i have been working on my engine for 6-8 months so the engine hasn't been started in a long time. i started the engine this week when i completed some of the repairs but never put the boat in gear so the shaft hasn't had a chance to spin in 6-8 months. apparently because i hadn't in so long the sealing surface between the carbon stator and the stainless ring began to corrode or have salt/debris get between them. enough to cause a nice leak.

the fix was simply to start the engine and put it in gear for 20-30 mins in my slip to wear/clean that sealing surface. its now drip free again.

so if you have a dripless seal it might be worth turning on the engine and putting it in gear once in a while as well, especially if you expect to not be able to get back to or take the boat out for a while...or if you plan to start doing some engine work where the boat may not be started again for quite some time. run it in gear for a while before you start to tear the engine apart.

i do have an older drip less seal and im not sure if there are newer versions that prevent this sort of thing? i'd be interested in hearing any advice or recommendations if the do exist.

[sailingchiro]

I have seen mine leak and typically it is a piece of sand, shell, or barnacle. Typically after cleaning my bottom. Open it up and let is wash away. If that doesn't do it, grab a rag and slide in the joint and spin around the shaft. Open back up and wash any residue out. Probably once a year.

[KadeyKrogen38]

Also do not forget that the bellows have a life span and have to be replaced, I believe every seven years is the recommendation.

[Althebass]

Originally Posted by GILow

I also fit a shaft anode in front of the seal as a fail-safe if the seal disk locking grub screws fail.

I think this fail-safe arrangement should be standard on all these shaft seals. Recently my PSS failed because the grub screws let go, so the slip ring slid forward and there was a big leak all of a sudden! Previously I've used a Jubilee clip but when I fitted a new prop shaft I omitted to refit one.


You might well ask why the grub screws failed. Well, I'd been in a tight manoeuvring situation in a narrow creek with a strong side wind - you get the picture - so I'd been overly quick going from forward to reverse, back and forth, in order to point my lovely long keel yacht in the desired direction. Them grub screws didn't like that! Moral: pause between selecting forward and reverse! (and drop your anchor to turn!)

[coastalexplorer]

Drip-less seals are NOT all created equal , the one that I removed from by boat was made by a manufacturer who vulcanized rubber around a steel spring, the rubber had perished so the spring had rusted. which possibly accounted for the previous owner reporting that when he bought the vessel there was 3inches of water in the bilge. ( think there were other contributing sources for this but the vessel had already been in dry-land storage for three years)


The company of PYI in Washingting state sell the PSS (packless sealing System) The bellow for their product is made completely out of Nitrile rubber without any springs in side, their installation and maintenance instructions an very detailed and copy write protected.


However Two important observations from that are>-

*6 year service life.
*do not use silicone, oil or grease to try to lubricate it.

I seem to recall they said I could use dish washing liquid to help with assembly.
*the amount of pre-load on the Nitrile bellows is specified,


To set this I applied the pressure with a clamp, measured it with a vernier Caliper, and asked my assistant on the outside of the vessel to lock the barrel shaped shaft zinc up against the back end of the stern tube to hold it there. This makes placement of the transmission and engine simple.
The zinc can be moved later.

[Symphony]

I have had 4 PYI PSS dripless systems in 4 different boats over the past 20 years. Older models need to be burped after haul-out, newer models have a small hose vent. Spec was a bellows life of 6-7 years, but none of mine ever needed replacement as they looked excellent even after 10 years. Clean the faces of the bearing in or out of the water, take a look at it when the engine is running - if there’s trouble or debris in the bearing you’ll see a fine mist blowing salt on your bilge and marine gear.

Consider the system and bellows like a large thru-hull, checking the bellows and its connections at both ends. Total failure of a bellows would be catastrophic though due to lack of any valve at the hull. They are very nice and allow for a dry bilge with no problem, but I know an expert delivery captain who despises them after a near sinking.

I’ll keep them on my current boat but I check them every time I get on board.

[leftbrainstuff]

Originally Posted by GILow

Pressure is simply a product of the depth below the waterline that the seal is situated. The make of seal does not change that.

My type is a PSS and the compression pressure is about what you’d expect, kinda firm, not particularly high or low. But yeah, the water comes out in quite a spray when I burp it.

It certainly sounds odd to me. I’ve thought about it a bit more and I wondered if maybe something small like a bit of seaweed might have somehow become trapped between the faces to allow that sort of seepage. My high school chemistry tells me salt crystals would have been washed out faster than they could form. I have trouble imagining them building up and causing a leak.

Oh, and sorry if you know this already, but just in case, most of these seals require that you replace the grub screws if you loosen them or reset the seal on the shaft, so do make sure you have fresh grub screws on hand if you do find you have to move the seal to adjust the compression.

I also fit a shaft anode in front of the seal as a fail-safe if the seal disk locking grub screws fail.

That's good advice