Wear in stern tube bearing

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Merlyn
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Re: Wear in stern tube bearing

Postby Merlyn » Mon Dec 05, 2016 12:37 am

Apportation of blame exercise here by the sounds of things?
Off with the engineers hat and on with the Sherlock Holmes lookalike job.
Like DW said checking logs, that special oil usage,( if it's monitored ) quizzing crew members etc etc.
Might be worth bearing in mind a lot of the smaller stuff re sterntubes has a water rail in and a water rail out fed under pressure.
Worked on a lot of those with never much troubles.
No lube oil feed whatsoever.
Just a visible water flow on some installations to see at a glance all is ok.
Surely someone must have noticed abnormal sterntube lube useage.
Might be worth a letter from the shaft/bearing manufactures, the written word never lies re the concerning failure rates/times / human error side of things.
It's a good launch platform for getting to the bottom of it all.
Difficult one to pin the blame in one place I would think.
Mr nobody again.
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

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Big Pete
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Re: Wear in stern tube bearing

Postby Big Pete » Thu Dec 15, 2016 5:58 am

I was interested to see the earlier mention of draining emulsified oil from the stern tube in Port. I was on one ship with a leaking stern tube seal where the Super was most insistent that we should shut off the header tank in Port and drain the emulsified oil from the stern tube by undoing the oil inlet pipe from the header tank to the stern tube, at the stern tube. In order to "Freshen up the oil", In my experience what then happened was that clean Sea Water then flowed into the outboard, lower end of the stern tube and displaced the emulsified oil into the Bilges, filling the stern tube with pure Sea / Dock Water making the situation worse rather than better.
I agree that the wear rate appears to be incredible and I find it very difficult to believe that that much wear happened in a couple of weeks, however I can not offer any evidence that would stand up in Court, only Gut feeling, the same as everyone else appears to have over this suggested wear rate. It appears most likely that there was a problem of oil loss and emulsification for months or years before the catastrophic failure that you describe. The records of oil consumption could be a key here, records of oil ordered and delivered and inventories if these are properly recorded of course. Although if the stern tube is using the same oil as the main engines it is difficult to prove where it went. Much easier if the stern tubes use a unique grade. But then if someone was trying to cover up excessive oil loss they would just chuck MELO in the stern tube, the MELO consumption is so large that an excessive stern tube consumption could be lost in it.
I imagine there are big insurance claims at stake here as well as the Engineers jobs being on the line.
I hope you can manage to find some evidence for what really happened.

BP.
It is always better to ask a stupid question than to do a stupid thing.

popeye62
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Re: Wear in stern tube bearing

Postby popeye62 » Fri Dec 16, 2016 12:40 am

Thanks Big Pete, all spot on and pretty much where I'm at. The LO is MELO and no there are no records. Now using Hydrox which if they had been using originally we would not be in this situation but that costs money and as we all know what ship owners are like.
Thanks Merlyn, it is nigh on impossible to get anything in writing from an OEM, a ship owner or a yard. I have made contact off the record with the industry and even then no-one can give me a definitive answer. I am just going to put my case forward, what I believe, and let them prove me wrong.

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Big Pete
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Re: Wear in stern tube bearing

Postby Big Pete » Fri Dec 16, 2016 1:43 am

One other thought, we had a thread on here about stern tube wear down readings, which might be worth reading.
In my opinion the sum of the Top and Bottom wear down / poker gauge readings should remain constant . It is the change in the difference between top and bottom readings that indicates the wear, since the previous reading, In my experience most Chiefs and Supers don't understand this, and "Flog" the wear down readings to something that they think shows a small but negligible wear down. It would be interesting to see if the recorded wear down readings make sense or are just random "Flogging of the Log.
Good Luck, and Merry Xmas!

BP.
It is always better to ask a stupid question than to do a stupid thing.

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D Winsor
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Re: Wear in stern tube bearing

Postby D Winsor » Fri Dec 16, 2016 4:32 am

I guess you are probably too far along in the repair at this point but did you consider retrofitting the sterntube with a water cooled and lubricated Thordon Bearing?
Over the past few years companies here in Canada that operate ships on the Great Lakes, a highly regulated and environmentally sensitive area when it comes to oil discharges accidental or otherwise, have been very proactive in the retrofitting their older ships with oil filled sterntubes and current crop of new ships with these type of bearings. So far they have worked quite well even in less ideal conditions, muddy & silty water,ice and shallow water cavitation, that would destroy some wooden stave or cutlass rubber sterntubes and the seals on oil filled tubes. Plus doing so eliminates a major environmental pollution hazard and all the very expensive legal consequences related to the uncontrolled discharge of oil.
Troubleshooting 101 "Don't over think it - K.I.S.S. it"

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JK
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Re: Wear in stern tube bearing

Postby JK » Fri Dec 16, 2016 3:30 pm

Thordon does a bearing suitable for silty water. I used it in smaller ship with good results.

I read this thread this morning and had a laugh at the bucketing of emulsified oil. That was the very first job I was given when I joined my first ship as a junior. Misery loves company and 35 years later the oiler who was with me for those 2 days is still a good friend.
I had to pick the phone up and have a yack at him. Only difference is we're older, he's investigates and I do projects. We've come a long way baby LOL


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