this should not happen

[Kevin]

Multiple injuries after ship tips over at Edinburgh dockyard - BBC News

[Knocklouder]

Ouch!!

[Keith Black]

 Reminds of a time in Alaska when a container barge tied up to the Diamond E docks in Egegik, Alaska. The tides in the Egegik River in Bristol Bay can range from  17 + feet to less than a foot. Anyway, this barge tied up at high tide to the dock's dolphins. The hawsers were steel cable but the barge crew didn't shaken off the hawsers (after tying up they went to one bar in the village and immediately forgot about the barge) as the tide ran out. Welp, when the tide neared low point the hawsers tightened around the dolphins till the tops (above the where the hawsers where attached) exploded, literally, and of course the barge listed some 30 degrees to port away from the dock threatening to dump it's container cargo into the river. It was a six hour mad scramble trying to keep the barge from rolling till the tide started coming in enough to float the hull. It took another 24 hours burying deadmen below and above the dock where the barge could attach and finish unloading. 

 

 Needless to say, it's exciting times when a large ship rolls are almost rolls. Luckily in the above incident there wasn't a loss of life. Being crushed to death in those circumstances is a very real possibility........they that go down to sea in ships. 

[mgdawson]

Speaking from my limited experience of drydocking ships, I just don't see how that could have happened unless there was a serious error in the blocking.

 

It'll be interesting to see what conclusions the investigation comes to.

[Dr PR]

Accidents should never happen - but they do.

[Rik Thistle]

Given the number of casualties, some of them serious, it seems the structure supporting the hull in the dry dock gave way suddenly - no one had warning so no chance to brace themselves.

 

The Petrel has been moored at Leith since September 3, 2020, due to "operational challenges" from the pandemic, according to a statement on the vessel's social media page. - https://www.edinburghlive.co.uk/news/edinburgh-news/seven-casualties-remain-edinburgh-hospital-26543218

 

So the ship had been sitting in dry dock for around 2 1/2 yrs, and probably not moved. I wonder what the inspection procedure is for checking the integrity of the supports, as time goes by?

 

Richard

[realworkingsailor]

I doubt the ship was dry docked for that amount of time. That would cost a fortune, and cost the commercial shipyard a lot of lost business having a dock occupied for that amount of time. Tied up at a lay-by berth is what they’re referring to.
 

Modern dock supports are steel with wood bolsters bolted in place on top.
I did read that there were high winds at the time the ship was knocked off the blocks so it’s possible that either the blocks were not in the right place, or the ship shifted during the pump out and didn’t land correctly on the blocks. I wouldn’t speculate any further until the MAIB or whichever investigation authority is overseeing this incident, publishes its report.

 

Andy

[Kevin]

1 hour ago, realworkingsailor said:

I doubt the ship was dry docked for that amount of time. That would cost a fortune, and cost the commercial shipyard a lot of lost business having a dock occupied for that amount of time. Tied up at a lay-by berth is what they’re referring to.
 

Modern dock supports are steel with wood bolsters bolted in place on top.
I did read that there were high winds at the time the ship was knocked off the blocks so it’s possible that either the blocks were not in the right place, or the ship shifted during the pump out and didn’t land correctly on the blocks. I wouldn’t speculate any further until the MAIB or whichever investigation authority is overseeing this incident, publishes its report.

 

Andy

from the photo she looks quite cleans so possibly flooding up, and caught by the gusting winds

[realworkingsailor]

7 minutes ago, Kevin said:

from the photo she looks quite cleans so possibly flooding up, and caught by the gusting winds

Possibly painted while in the dock. Surprisingly, with the right amount of labour a large ship can be fully sandblasted and painted in a remarkably short period of time (about a week).
If the ship was in any way waterborne at the time, it shouldn’t have toppled like that, unless something serious was done to alter the CG of the ship. Most, if not all, commercial dry docks don’t use the old methods where there’s only a single row of blocks under the keel and shoring beams to hold the ship up. Although there are still more blocks down the centreline, there are typically one or more rows of blocks on each side, depending on how wide the ship is. 
 

Submarines are, of course, the exception as they usually don’t have flat bottoms…. 😁 
 

Andy

[Matt D]

Caption on a photo about halfway down the article: “The Petrel was pictured in an neighbouring berth in January, before being moved into the dry dock.”

 

So she has only been in dry dock a short while.

[Jim Rogers]

In 1977 I was stationed on the USS Piedmont AD17 and we were in dry dock at the Todd Shipyard in Norfolk VA.  They decided to refloat the ship on a Sunday afternoon using the duty section. I was sleeping down in the ASROC shop when one of my buddies comes running down screaming ‘Jim they just passed Abandon Ship’ I told him that was ‘ BS you don’t abandon ship in a dry dock’ and then I hear ‘All Hands Abandon Ship, this is not a drill ‘. HOLY CRAP. Off we dash up to the main deck. Then over the 1MC, ‘All Hands belay our last. All hands move to Starboard side Main Deck and remain until further instruction’….

 What had happened was they had removed all the machines from the starboard side of the machine shop and left all the matching machines on the port side. These were some giant lathes and presses that could be used to machine Battleship engine parts and they weighed tons. They had not compensated for the weight loss and as soon as the ship started floating He, yes HE Doc Piedmont the only He ship in the Navy, started rolling Port and slipping off the blocks. Quite the list, they used the crew as a counter balance until we could be dry docked again on the blocks. They mustered the relief duty section early so we could have breaks. Took several hours to get corrected.

[Kevin]

1 hour ago, realworkingsailor said:

Possibly painted while in the dock. Surprisingly, with the right amount of labour a large ship can be fully sandblasted and painted in a remarkably short period of time (about a week).
If the ship was in any way waterborne at the time, it shouldn’t have toppled like that, unless something serious was done to alter the CG of the ship. Most, if not all, commercial dry docks don’t use the old methods where there’s only a single row of blocks under the keel and shoring beams to hold the ship up. Although there are still more blocks down the centreline, there are typically one or more rows of blocks on each side, depending on how wide the ship is. 
 

Submarines are, of course, the exception as they usually don’t have flat bottoms…. 😁 
 

Andy

each class of sub had its own set of curved blocks, however the old diesel boats had a flat bottom to enable sitting on the seabed, and i remember standard blocks with wooden props to keep her upright

Edited March 25, 2023 by Kevin

[Robere210]

Ai Yi Yi!! Somebody screwed up.  Glad no one was killed.

[Rik Thistle]

An insight as to why the vessel might have shifted ..... UPDATE: R/V Petrel - https://www.youtube.com/watch?v=Mg8nZy7KVTw 

 

TLDR: The side braces may have failed or been fitted incorrectly. Some of the Comments below the YT video are interesting.

 

One of the Comments raises the issue about the side braces/shores being used in tension rather than compression, since compression will lead to buckling whereas tension tends to (usually) stretch the brace material within it's elastic limit. But if tension is used then that means the brace must be securely attached to the dock and the hull.

 

Richard

Edited April 12, 2023 by Rik Thistle

[realworkingsailor]

Interesting video. Also interesting that the dry dock in question uses the older method, keel blocks and shores.

 

If the vlogger is correct in his assessment, it looks like a lack of shoring is probably the root cause of this incident. Not sure what their calculation criteria are, but that would highlight a failure to take into account wind loading on the superstructure of the ship. That helipad forward could potentially catch a lot of wind depending on how turbulent it was around the bow (updrafts?)
 

I’d be careful about some of those video feedback comments, I skimmed through a few and I have less than complimentary opinions about more than a few of them. Generally speaking shores are used in compression, as it does not require fittings to be welded to the hull (costly and time consuming). Shores are more commonly fixed to the hull if it’s a long term dry docking, think museum ship.
 

Andy

[Rik Thistle]

Andy,

 

Yes, some of the Comments were a bit confusing, but some seemed to show experience in that industry. I have no experience in that industry - I'm just an ex-Mechanical Design Engineer interested in all forms of technology.

 

For me, what came out of the video and the Comments was that the vessel would carry with it instructions on how to 'dry dock' it. The vessel owners would then sign off on whether that work was done correctly. Then as painting the hull etc was carried out the maintenance team would have to follow a strict set of procedures eg maintaining the CoG position.

 

It will be interesting to see what the Investigators come up with.

 

Richard

 

[NavyShooter]

Rumble I heard was that they were painting the hull, and so my thought is that maybe they had some of the shoring had been removed to paint a section, then they put it back in place incorrectly?  The Shores are supposed to be lined up correctly with the hull frames to give the right support.  If they'd removed some shores, and put them back slightly offset from the actual frame, then it would be pressing on the hull plate rather than the frame, which has some give to it, and in high winds (25 knot winds were forecast that day?), could have compressed/loosened the shores, and if one or two fell due to improper placement, then it would likely lead to a domino effect.

 

 

[realworkingsailor]

The CG question/comment is a bit of a red herring. If the CG was so high that it alone caused the ship to topple in while dry dock, there’s no way that ship should ever even have been allowed near water to begin with.  

As an engineer I’m sure you already know that an object on solid ground will not topple over unless its CG is forced outside of its footprint on the ground.
 

For anyone else who’s unsure:  if you consider a transport truck (or lorry, whatever your personal terminology preference), regardless of how high the load is, the vehicle remains stable provided the centre of gravity remains somewhere between the outside edge of the tires (tyres).
 

In the case of this ship in dry dock, correctly shored (or blocked) the CG would have had to shift laterally, beyond the ship’s side (or outermost row of blocks) for it to topple. If the shores were fixed to the ship’s side, the CG would have to shift beyond where the shores meet the dockside.
 

I’ve seen the docking plans for the dry cargo ships I’ve worked on. Most of them just show the required block placement, the drain plugs for the various tanks, as well as other various inlets and outlets in the hull (pump intakes, etc). I don’t recall seeing much on shoring, as it has become an extremely rare form of dry docking.

 

For what it’s worth, even on an extremely shapely hull form, like the Petrel, there was enough of a flat bottom that an outboard row of blocks could have been placed (even if it was only in the midship area). She didn’t specifically need to be dry docked as she was.

 

I agree, though, that it will be interesting to see what the MAIB has to say.

 

Andy

[Kevin]