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Andy

Cargo ship capsizes in Channel

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43 minutes ago, Gareth said:

That's astonishing!

Will they sink it as a hazard I wonder, or where will it end up if drifting 'west' towards Cotentin?

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She's now accompanied by the Galatea, a British registered wreck marker plus a French & a Danish warship.

Abeille Languedoc is also enroute.

Edited by jonno

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It seems they managed to get a tow line attached to her this afternoon by paying it through the bow thruster tunnel and are now trying to pull her towards the coast before the weather deteriorates later this evening. There are also 4 cargo-hold hatch-covers floating around which the British ship is trying to recover or, if it's not possible, mark so they don't present a danger to other shipping. 

https://cherbourg.maville.com/actu/actudet_-cherbourg.-le-cargo-naufrage-est-remorque-par-l-abeille-liberte_loc-3405892_actu.Htm

Ed

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Quite extraordinary that a simple collision with a fishing vessel should result in turning turtle.  I’d have thought she’d either have been badly damaged (and therefore just sunk) or not.  Can’t conceive of how a collision with a little fishing boat could have resulted in a 180 degree capsize.  Unless she was overloaded and therefore highly unstable?  But cudos to the salvage company if they manage to safe her.

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But Deborah isn't just a little fishing boat Gareth; she actually measures almost 38 metres long according to AIS, that's nearly half the length of Britannica HAV at 82 metres so maybe not quite so astonishing after all. But you would have thought with all the gadgets available today this sort of collision should be a thing of the past....

Chris

DEBORAH

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Still astonishing Chris - turning turtle is not a normal response to a collision.  Usually takes exceptionally high seas to achieve that.  I could understand her just sinking in a hurry.  But turning turtle whilst still afloat is very peculiar.  Somehow or other, the stability of the ship must have been severely compromised without taking on enough water to sink her outright.  Difficult to conceive that just taking on water could have resulted in that.  Something like getting caught up in trawling nets might explain it?

Whatever it was that caused the ship to turn over was clearly not catastrophic, but a slow development of the situation.  The crew had time to evacuate to lifeboats.  Very odd.

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It would be helpful to see a photo of the the trawler taken since the incident to see the damage she has sustained. That might shed some light on the sequence of events and the relative positions of the vessels at the time, particularly as it seems the collision was in broad daylight. Ed

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2 hours ago, Gareth said:

Difficult to conceive that just taking on water could have resulted in that.

Free surface effect is just as deadly to bulk carriers as it is to ferries especially on a vessel with such a shallow freeboard as those like Britannica HAV. Didn't sink though?

Edited by jonno

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Free surface effect requires ingress of water above the waterline.  Maybe something like that happened as the two vessels separated.  But I thought that it was only roro vessels that had the large uncomparentalised areas of deck that the FSE needed?

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She was carrying a cargo of steel, if the hold started to flood quickly and then she started to list the steel moved and over she went and the weight of the steel went through the hatch’s, they were reported to be floating and a hazard to shipping. If that was the case the ship would still have a fair amount of buoyancy.

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There are plenty of photos of her online lying very low in the water. If that was the case here, probably confirmed by the photo of the damage to the trawler, then the fishing vessel's prow might have broken open one hatch while at the same time pushing the ship even lower in the water and inducing the start of a roll over. Then the water pouring into the damaged hold did the rest. If the other 3 hatches held until she was upside down, and only broke off due to the weight of the cargo breaking loose, then the air inside would be plenty to keep her afloat. She also has very little superstructure to weigh her down. Ed. 

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FSE will occur anywhere it has the space to do so it's just less of an issue the lower it occurs.

What about what we have here, a sudden explosive penetration on her port or starboard side made by a vessel under power, this will immediately cause the vessel to list then roll back again allowing the sea in. As the water returns to its initial ingress point very rapidly due to velocity it causes a rocking motion increased by her load moving which creates more instability and FSE.

We have volume of liquid + Inundation velocity + turbulent flow which creates free surface vortices especially in unbaffled vessels and a heavy insecure load not ot mention a very shallow actual freeboard, possibly C2 and around 500mm and not the one created by her augmented hold height. 

This hold height is probably what kept her afloat, trapped air in a large area unconnected to the main body of the vessel by doorways or shafts... a bit like  Burt Lancaster and Nick Cravat in the Crimson Pirate walking along the seabed in an upturned lifeboat and copied by Johnny Depp.

Solas regs for freight shipping are slightly different to that of pax vessels. One is set up for the safe rescue of the crew the other for the safe evacuation of passengers and safe rescue of the crew. None of them are particularly concerned with the ultimate fate of the vessel plus there's a big difference between rescue and evacuation.

Sinking... or not yet anyway. 

One main theory which is regularly used.

Once a vessel turns over the water equalises to sea level, flowing back down from the spaces which are now above the waterline with the remaining space filled with air keeping her buoyant. The more compressed this air is the more buoyant she becomes especially in the tight engine spaces which are now above and trapped in crew spaces below. The more compartmentalised a vessel is the longer they remain afloat. Air can be compressed far more than seawater and consequently weighs more. At equalisation buoyancy wins the battle... Physics hasn't changed unless we've all moved to Jupiter.

The downside is that sooner or later the compressed air becomes so pressurised that false non structure walls collapse allowing water to fill the spaces as it re equalises making the hull heavier which in turn increases the air pressure. On and on it goes until eventually the air can escape consistently and regularly, possibly through a blown prop shaft seal for example, she'll then founder and be lost.

Towing the capsized hull of Britannica HAV to Le Havre means they can continue pumping air in to her until the owners decide her fate.

Ferries. 

 RoPax vessels are now built on the assumption they will suffer from FSE, it's why the more modern ships can still be stable with a 60cm depth across their vehicle deck 3, they have vehicle deck compartment shutters, faster, larger volume pumps and have watertight fire doors upto deck 5 (like the Pont), they can roll a lot further without being inundated on the opposite side... unless the damage is so catastrophic that the vessel will be lost anyway.

It's a design which also stops them capsizing when they are flooded with tonnes of seawater combatting fire hence the reason why Norman Atlantic remained afloat. An area can be sealed allowing the fire to fought in a more controllable way and more importantly limit the amount of oxygen they get. A Visentini's may not be the most gracious of vessels but they are built very well.

 

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