leaking deep sea seal

[stephen_warby]

I can't tell how happy I am to find this forum!
I've read PBO fro that last ten years or more and could never get enough and I now I can actually ask questions!
My question this time concerns the Deep Sea Seal (rubber boots with bronzy ring sort of surface to surface seal) on my propellor shaft. It was new and after 3 years with the boat ashore for refit it has leaked for the last 3 years when the engine is running. My boat is steel so I really don't want a leak. I contacted the manufacturers and they werehelpful but not sure. I have checked that it is evenly aligned, pushed the two boots closer together but the seal still leaks after all this time. The boat is coming out of the water in 8 weeks and I want to get it working if possible. It has been sugested to me that there is grit caught in the seal or that I should grind the surfaces down a bit with wet and dry paper over a peice of glass but that could make it worse. Does anyone have experience of this sort of problem and maybe a solution?

Thanks Stephen

 

[Guest]

I had one installed on my last boat. year one was excellent, but by year 3 it was weeping. it also had a tendency for the ring to stick to the bronze. took it off, took it to the boat show and raised the problem on the stand. didnt intend to embarrass them but they gave me a new one which i then sold on to someone else at the club!

i didnt think it was a good system so i changed over to one of those where you have a brass sleeve round the shaft, sealed with lip seals and filled with oil from a reservoir. it proved to be excellent, with never a single drop of water for all the time we had the boat.

the deep sea seal will wear in use, and unless you are lucky enough for it to wear completely evenly across the whole area that is covered by the mating surfaces, it seems to me that it will weep a bit. ceratinly, mine did. but then, so does a stuffing gland.

 

[jfkal]

Fully agree. New one or better oil seal type.

 

[ChrisP]

I fitted them to my Freeman and had nothing but trouble with them. I turned out the the the bronzre ring had seperated from the rubber mount and the water was passing round the back of the ring and getting in that way. We even found a leaf stuck in there. The manufacturers finaly coughed up but I went back to a packed gland and no further trouble.
Horror of horror's when we bought our present boat there lurking in the gloom. You guessed it, deep sea seals. But I have to say in the year we've had the boat the only water we've had in is when we threw an engine mounting and the shaft went out of line.

Fingers crossed.
ChrisP;o)

What do you mean the sea gull in front's walking !!!

 

[philip_stevens]

A friend of mine changed from a Volvo lip seal to a Deep Sea Seal. Why? I could never understand. He never had a leak with the Volvo seal, but changed it when he replaced his engine.

The Deep Sea Seal is the same as the Crane seals we used on pumps on the containerships I was on (before I retired). These (Crane) were stainless steel plates on one side, with a ring of a ceramic on the other face. Deep Sea seals are similar with a "brass" plate affixed to the stern tube with a ring of copper impregnated tufnol on the shaft.

What appears to make them leak, is corrosion within the tufnol/brass contact area. The Fulmar that had this on, leaked like hell when put into the water after wintering ashore. So much so, that I had to dry out between tides as it was pouring/spraying in. The remedy was to put extra fine emery/crocus paper between the faces and rotate the emery/crocus against the brass plate, and then do the opposite against the tufnol - keeping the emery/crocus fixed in this instance.

Do not put any lubrication between the faces after bedding in. The faces must be lubricant free during use.

When winterising, pull the shaft ring away from the tube plate and spray with (the dreaded) WD40. This is one of the times when I will advise use of WD40. After the winter clean both faces with spirits and you "should" get a dry joint.

Anyway, this is what I had to do with the friends boat when I was looking after her. He forgot to pull the faces apart or apply any anti corrosion liquid. It may work for you.

regards,
Philip

 

[30boat]

I think you've been unlucky.In my experience the deep sea seal is very efective providing everything is properly aligned.I've fitted one to my Fulmar after having one for the last 6 years on my previous boat with no problems whatsoever.What will make them leak is excessive movement either sideways or fore and aft.I have an aquadrive wich efectively keeps the seal aligned at all times.There was a thread some time ago with nothing but praise for these seals.

 

[stephen_warby]

Thanks heaps for the reponses. I see hope for my boat's little problem. What grade of emery paper would you recommend, 500, 1000?

Cheers
Stephen

 

[philip_stevens]

VERY fine - like wet and dry for car rubbing down/finishing. Start with 500 and finish with 1000.

It's worth a go.

Good luck.

regards,
Philip

 

[stephen_warby]

Thanks a million Phillip!

 

[vyv_cox]

Don't miss the point made earlier. The grinding marks must be concentric. If you use a reciprocating action the seal will not function. Use this motion initially if you need to take out deep scores but finish off by the circular action described. The finest papers you can get should be used, they are available up to 4000 grit. Commercially these seals are finished by polishing and lapping and the flatness is measured in light bands. You won't achieve this but it should be possible to improve on the current situation. Polishing/grinding with the paper on a small square of plate glass is an old method to achieve good flatness.

Mechanical seals can work fine, but what they really cannot cope with is abrasive particles. When reassembling the unit, flush the stern tube, shaft and the seal with water from a hosepipe. If there is any sand or mud on the hull around the propshaft, clean that off as well.

 

[philip_stevens]

Vyv,
thanks for expanding (expounding?) my method. I knew that what I did, worked, but explaining it was more difficult. Yes, I did rotate the "shaft" element abrasive against the tube part, and kept the tube abrasive fixed while rotating the shaft part. That made the abrasions concentric. As I said, it did work - after having to rush to put the boat aground.

regards,
Philip