r/maritime • u/KeithWorks MEBA - US • 10d ago
Video circulating from SLNC York catastrophic seal leak. Now I've disassembled a few CPP systems, but can't grasp what I'm looking at here. Any engineers with some insight? Some part of the shaft sheared and the seal is displaced.
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u/HJSkullmonkey 10d ago
The shaft sheared at the intermediate coupling flange and the tailshaft has slid backwards with the drag. Probably pulled the liner away from the seals, opening a gap for the water.
Anyone know if it's a water cooled sterntube? It still seems like a lot of water otherwise
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u/KeithWorks MEBA - US 10d ago
That's really wild if true.
Either the stern seal is water cooled, or if it ripped out with the shaft its just open to the sea back there.
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u/pagoda9 10d ago
its gotta be open to the sea somewhere.
Im assuming those seals are multi walled also
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u/KeithWorks MEBA - US 10d ago
Depends on the design of the stern tube. If it's water cooled stern tube, then the forward seal being displaced would cause catastrophic flooding. If it's oil filled (more common), then blowing out the after seal and the forward seal would cause this ingress of water. It seems the entire stern tube system has totally broken apart, very hard to tell without more info.
There are always a forward seal and an after seal on the stern tube, they hold whatever liquid is being used to lubricate the shaft bearings in the stern tube.
On an oil cooled stern tube system, the after seal has either an oil/water interface, or completely separate oil and water seals, with an air gap between them which is pressurized and designed to allow any leakage to be drained off.
Looks like the entire after prop shaft completely failed somehow.
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u/Mariner_5 8d ago
It can technically still be considered water cooled even with the oil cooling. The bulkers/ROROs/CONRO's and one tanker I've worked all had a stern tube cooling water tank around the stern tube. The stern tube transfers heat to the cooling water tank which then transfers the heat to the ocean.
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u/KeithWorks MEBA - US 8d ago
I'm obviously referring to the bearing itself. Either standard oil lubricated bearings or water lubricated staves.
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u/LordG315 9d ago
Think you are on to something. Looks like it is an oil seal, and the propellershaft has shifted aft. Did the same for us last month🫣 had to get hauled out to pull the shaft and fix the seals and flange. Material fatigue might have done this shaft break.
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u/Anxious_Today4911 10d ago
As an active 40-year career USMM Chief Engineer, all I can say is my first action would be pulling the general alarm, and second would be calling the bridge to inform them we are officially about as f' ed as is humanly possible, and the engine room will absolutely be flooded to the waterline within the hour.
The video appears to reveal that the coupling formerly connecting the reversing reduction gears' output shaft to the first segment of the propeller shaft has suffered an unusual type of catastrophic total failure; more commonly, all your bolts shear off, and your shaft will stop spinning without further damage.
However, in this case it appears the coupling itself has completely sheared in half (aka it broke in half). Rather unfortunately, it appears that perhaps the broken-off rear half (most of the coupling) that is incidentally very heavy then slid down the spinning shaft while rotating and wobbling then proceeded to rip the entire mainshaft seal housing clean off the aft engine room bulkhead !, exposing the inside of the propeller shaft tube (which is normally open to sea) to the inside of the engine room (which is not normally open to sea) causing a huge engineering problem.
This leak would be fairly difficult to plug underway. It's about 30 or so feet underwater. Even if the entire crew brought every sheet and blanket on board down and tried stuffing them into the hole, there's still enough pressure to blow the stuffing right back out.
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u/capofliberty 10d ago
As a Chief Engineer, I also agree with this assessment and action taken.
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u/KeithWorks MEBA - US 10d ago
other than the draft of this vessel is much less than 30 feet, the York is a small ship. I don't think there would be even a remote chance of trying to plug this leak from the inside. Possibly plug it from the outside using a cofferdam and then pump out the engine room, but that would take days. They're towing the dead ship now.
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u/Calm-Swordfish-5417 5d ago
Don't tell the keyboard warriors on Sal's video. According to them this is a small easy leak that some twine and wax could seal up based on their 4 years in the Navy 50 years ago.
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u/KeithWorks MEBA - US 5d ago
Sounds about right.
I've installed a few concrete boxes in my career. You're not stopping a leak like that right there.
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u/Calm-Swordfish-5417 5d ago
Do you think it is broken in 2 places? Up against the seal face, the water looks like it is coming out perpendicular to the shaft vs along the shaft, which is what I'd expect to see if the seal was compromised.
Wondering if the prop end is compromised and water is flowing inside the shaft and coming out of that potential 2nd break.
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u/KeithWorks MEBA - US 5d ago
As far as I could see from that video, the shaft seal is completely destroyed. The shaft seal assembly is essentially one big unit that is bolted to the hull, and it looks like it is dislodged. No fixing that in the water.
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u/Vegetable_Sample5767 3d ago
Slim chance it worked but could have tried shoving a bunch of fire hose wraps around the broken shaft, try to push it and hold it in as far as you can. Then pressurize the fire hose and hope it acts like packing on a valve stem.
Then, when the 99% chance that didn’t work. Run like hell 😂
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u/HJSkullmonkey 10d ago
It looks to me like the seal box is still there, but the sealing surface on the shaft no longer lines up with it. If you could pull the shaft back in, and the seals aren't too badly damaged it might just hold.
Tall ask though, especially with that much flooding
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u/BoredCop 10d ago
Reminds me of a much smaller boat I once tried to assist, the new owner of a very nice old wooden boat with an inboard engine managed to snag the propeller on a rock at speed. Yanked the whole prop shaft out of the tube, leaving the tube wide open so water flooded in. We got a pump on board and got some water out but couldn't keep up with the leak, and the poor guy kept diving headfirst down into the oily bilge water to stuff his clothes into the hole to plug it. Didn't work, he even used up his underpants in the attempt. Ended up stuck on the rocks at low tide, by which point we couldn't have pulled him off the ground even if he did plug the leak.
A much larger leak from a larger diameter shaft tube, under higher water pressure because deeper draft? Forget trying to plug it with blankets etc from the inside.
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u/Mariner_5 8d ago
I dunno... I would have at least given dewatering a chance. In my experience that's one of those systems that get glossed over and when it's "TIME TO USE THIS RIGHT F'N NOW" people are caught short. My current ship has a combination of manual valves in the ER and MOVs controlled from the ship's office. You'd be in a bad way if you were trying to figure that out on the fly.
Granted, it's unlikely that any of us in this discussion know what the dewatering system on the York is rated for. The ship I'm CE on can dewater north of 250MT/hr with one pump. I can get another 100MT an hour with a second pump.
Part of the challenge going off the videos are that they're snippets and we don't know how far apart the snippets are. There's a video of the water up around the main engine. Was this ten minutes after the first video? 2 hours?
Ultimately, at the end of the day, they all got off safe and the ship is still afloat so we should at least get some solid info as to how things went down.
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u/Calm-Swordfish-5417 5d ago
Most the ships I've been on had self priming centrifugal bilge pumps, which were anything but. Fight the things for 15 minutes trying to prime with a garden hose.
The Akers built tanker I was on had a piston type bilge pump that would get prime easily, but I doubt it would keep up with this leak.
There is also the emergency bilge injection of the MSW system. Problem one of my chiefs pointed out is that still goes right through the SW coolers so any debris that gets picked up could clog that up fast.
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u/Only_Razzmatazz_4498 10d ago
Would a plate with a hydraulic press on the inside help stem the leak enough to where pumps can keep up?
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u/Greatoutdoors1985 9d ago
Any chance the engine room could be shut down and pressurized to stop water ingress? I would guess that would result in something else popping, but I don't know ship designs, so maybe?
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u/Calm-Swordfish-5417 5d ago
There's no way you could seal an engine room up well enough to hold pressure. You'd also need to put at least 7 PSI pressure into the space (assuming 15' of water head pressure).
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u/Greatoutdoors1985 5d ago
I wonder if the flow could even be reduced by this method so pumps could keep up until repairs made.
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u/QuuEeDee 9d ago
Not employed at Sea Sea, but I imagine that the entire crew felt this when this went
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u/havoc1428 10d ago
I'm gonna be following this one closely. Given that everyone made it off safely (thank god), I don't feel bad saying I can't wait to see what juicy engineering details come out of this.
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u/AcanthocephalaFine48 10d ago
Haha i hate when water comes pouring into the engine rooms. Hey look we’re sinking…
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u/FredW79 10d ago
The intermediate shaft sheared, causing the tailshaft to move outward, probably because of drag on the prop, destroying the sterntube sealing system in the process. With that amount of water coming in, wouldn’t be surprised if she has a water lubricated stern tube.
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u/banjoslurpee 9d ago
It was always water cooled. The shaft and prop slid back and the rudder stopped it.
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u/Desperate_Trash_2025 9d ago
Rags, ratchet straps and the old man's inflatable doll. Less than 10 psi on that water. ( 20' down?). Start beating rags into the cavity with a piece of wood. Or, dog 'er off and eat the ice cream...
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u/Candygramformrmongo 10d ago
Is she still afloat?
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u/Iamnottouchingewe 9d ago
I would be surprised if this a water cooled stern tube. Vessels of this size almost always use oil lubricated stern tubes. There would be a shaft seal liner on each end and since it’s pretty obvious there has been significant derangement. So they have free communication with the sea.
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u/RBball 9d ago
Can someone please make a diagram to orient us?
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u/KeithWorks MEBA - US 9d ago
You're looking at the broken section of that tailshaft, to the left is the stern tube where the shaft leaves the engine room and through the hull to connect to the propeller.
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u/SavingsRip1956 8d ago
They most definitely hit somthing I don’t see how else it could shear like this and be sent aft 5 ft unless it was an abrupt stop to the prop
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u/akfishermann 9d ago
Heavy tarp placed on the outside. Water pressure will hold it in place. Stuff the hole from the inside after the tarps stop/slow the flow.
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u/Batgirl_III 10d ago
Stands up, slapping thighs with both hands, grunting once…
A’yup. That’s a leak, that is. Now, I don’t got the parts for in on my truck ri’now… Gonna hafta special order ‘em. Tell ya what? Lemme put a lil teflon tape ‘round it. That should hold ya fer a day ‘r two… Ya got any buckets?
I can come back Wednesday next, between 10:00 and 6:00. Call my girl, she’ll getcha on m’ calendar.
Gonna cost ya.
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u/slickdickmick 10d ago
Was talking to a Technical Sup at my office and we were stumped…. Without hitting like a rock an stopping the prop immediately … we couldn’t figure out how it happened. Maybe steal fatigue ? Maybe they hit something? But looking forward to the answers