AndyPandy
Well-Known Member
Might be interesting
sinking of the Concordia on ch4 now
- Thread starter AndyPandy
- Start date
sailorman
Well-Known Member
Housey Housey 
Greenheart
Well-Known Member
I hope you gents are watching this. Really shows how close to a wholesale calamity it came. Scary stuff.
FWB
N/A
Sobering.
AndyPandy
Well-Known Member
Yep, very scary indeed.
Fire99
Well-Known Member
An interesting watch. Some of the crew seemed completely out of their depth (excuse the pun)..
All the modern safety gear but one thing seems to have been overlooked.. Crew training in the event of this kind of situation.
All the modern safety gear but one thing seems to have been overlooked.. Crew training in the event of this kind of situation.
Greenheart
Well-Known Member
Considering the enormity of the construction programme involved in building a ship this size, how prohibitively would it be increased, by adding a second, inner skin, all the way up to the waterline? So that a catastrophic rupture of the outer hull, wouldn't flood the ship?
I think I heard that plenty of modern oil tankers do that already, rather than risk the hideous pollution we've seen previously.
I guess the inner skin would need to be well inboard of the outer, to avoid the same rupturing element - but presumably the thickness of the inner skin could be considerably lighter - in use, it might be damming thousands of tonnes of water, but it wouldn't have to resist waves and turbulence.
Seeing that such a design alteration would have saved Titanic and Costa Concordia and who knows how many other total losses, it might be worth calculating what percentage an 'inner skin' would add in costs, to be set against the potential cost of losing the ship.
I think I heard that plenty of modern oil tankers do that already, rather than risk the hideous pollution we've seen previously.
I guess the inner skin would need to be well inboard of the outer, to avoid the same rupturing element - but presumably the thickness of the inner skin could be considerably lighter - in use, it might be damming thousands of tonnes of water, but it wouldn't have to resist waves and turbulence.
Seeing that such a design alteration would have saved Titanic and Costa Concordia and who knows how many other total losses, it might be worth calculating what percentage an 'inner skin' would add in costs, to be set against the potential cost of losing the ship.
saltylegs
Well-Known Member
IIRC Titanic had the inner skin but not all the way to the top. (prepared to be corrected).
but the scary bit with the concordia was that she was in 100 m (according to the bridge voice records) and drifted to the shore, imagine if she had rooled in the deeper water
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Greenheart
Well-Known Member
That's the point, as I understand it: cruise ships today take care to double the hull in places, but not as high as the waterline. So, any serious damage below the waterline but above the double hull, may spell the ship's end.
I was amazed to read that Costa Concordia is expected to be refloated and returned to her construction yard, mainly with the use of vast buoyancy tanks. That, I'll want to see!
Woodlouse
Well-Known Member
Both Titanic and Costa Concordia had double bottoms, but the second skin didn't extend at all to the sides of either ship.
I believe double bottoms have been common place in iron ships for a very long time. A complete double hull however is just not worth the extra cost. The theory being that having water tight bulkheads should in most cases prevent the ship from foundering. Why this didn't work for Titanic is well documented, what happened to the Concordia I don't know, I've not been following the story that closely.
Double hulls are mandatory for all new oil tankers and have been for some time (since about the Exxon Valdez). This is because of the obvious ramifications of rupturing the hull whether it endangers the ship or not. Normal passenger and cargo ships aren't such a danger to the environment if they're damaged or sunk.
I believe double bottoms have been common place in iron ships for a very long time. A complete double hull however is just not worth the extra cost. The theory being that having water tight bulkheads should in most cases prevent the ship from foundering. Why this didn't work for Titanic is well documented, what happened to the Concordia I don't know, I've not been following the story that closely.
Double hulls are mandatory for all new oil tankers and have been for some time (since about the Exxon Valdez). This is because of the obvious ramifications of rupturing the hull whether it endangers the ship or not. Normal passenger and cargo ships aren't such a danger to the environment if they're damaged or sunk.
Greenheart
Well-Known Member
I can well believe that expense has been the reason for not doubling the whole submerged hull, hitherto...but I can't believe it stands up as a good enough reason, against the loss of a £half-billion ship. And that's aside from the unquantifiable loss of life.
Woodlouse
Well-Known Member
As I said, water tight bulkheads should be enough to save the ship. In the instances that they're not I would have thought it likely that a double hull wouldn't do so either. It was a monstrous great rip in the side of the ship, who's to say it wouldn't have been deep enough to tear though an inner skin too.
landlockedpirate
Well-Known Member
It was difficult to tell from the footage but it looked like the watertight doors were not closed till about 30mins after the original collision.
Greenheart
Well-Known Member
It's certainly odd, that lots of really spectacularly awful incidents seem to have involved ships equipped with watertight doors which weren't utilised properly.
Is it too much, to suggest designing permanent restrictions into (presently) open stretches of under-waterline space, which are supposedly made safe by assiduous application of watertight doors?
If those sections of the hull were only ever accessible by stairways from above, they'd also only be at risk from flooding if penetrated from outside the hull.
In a hull the size of Concordia's, twenty permanently sealed sections would still be vast areas - not exactly claustrophobia-inducing - but damage such as Concordia or even Titanic suffered, would only have flooded localised portions of the ship.
Easier than a second, inner hull, surely? And safer, in a range of circumstances that are by their nature, unforseeable.
Is it too much, to suggest designing permanent restrictions into (presently) open stretches of under-waterline space, which are supposedly made safe by assiduous application of watertight doors?
If those sections of the hull were only ever accessible by stairways from above, they'd also only be at risk from flooding if penetrated from outside the hull.
In a hull the size of Concordia's, twenty permanently sealed sections would still be vast areas - not exactly claustrophobia-inducing - but damage such as Concordia or even Titanic suffered, would only have flooded localised portions of the ship.
Easier than a second, inner hull, surely? And safer, in a range of circumstances that are by their nature, unforseeable.
prv
Well-Known Member
In theory, of course, someone ought to be in command on the bridge, to close the doors as soon as there's any possibility of a problem. As we saw in this case (as well as another in the other sinking cruise-ships programme Channel 4 did recently) the officers all promptly ran away as soon as it started going wrong.
A good compromise would be for them to adopt the procedures that Stavros has for the watertight doors - if she had been sailing around that island the doors would have been closed as a precaution, as they always are when entering or leaving port, passing close to any other land, or in fog. It's a perfectly normal evolution on that ship, not an emergency action per se.
Tis a bit of a bugger though when you're in the shower in compartment two when they close the doors, and your berth is in compartment three. You have to go up the stairs by the front of the galley, trot down the side-deck draped in a towel, and go back down the main companionway from the waist (where everyone hangs around) and past the mess-room. Don't ask me how I know this
Pete
Greenheart
Well-Known Member
More midnight speculation...cripes, it's getting late...
Doubtless, segmented accommodation plans would limit the freedom of movement and convenience of the crew...but given the disasterous freedom of movement by water, which open areas permit, surely permanently sealed sections make sense?
It's only below the waterline, I'm supposing, that this would be necessary - because if one of 20 sealed areas supporting no more than 5% of the total displacement each, is breached, then it's unlikely the ship will list (or go down by the nose) far enough, to endanger accommodation areas above the waterline...
It'd be a lot of extra steel, and lots of stairways. But fairly small beer, compared with the £19,000,000 excess (yes, really!) which was part of Concordia's insurance.
It seems such an obvious preventative to monumentally dreadful sinkings, I can't figure why ships aren't built this way. I guess I haven't thought of something.
Perhaps there ought, in the ideal 'unsinkable' ship, to be a whole sealable deck, at the waterline - ie, watertight doors in the floor - such that however bad the damage below the waterline, that portion of the hull can be isolated.
So, if the whole 'bilge' flooded, she'd still float...very deep in the water, and very vulnerable...but not an imminent total loss.
If I recall correctly, Titanic sank because incoming water drew the bow down, and nothing prevented its rising within the comparmentalised hull - so when the hull dipped under the increased displacement, the water flooded vertically, over the 'sealed' sections.
If the waterline had been sealable - by the deck at that point being built as strongly as the outer hull, with watertight doors enabling access except during inundation - then the flooded 'bilge' could scarcely have sunk the ship. No?
Maybe access hatches in the deck, could have 'floating' watertight doors - which wouldn't need operators - they'd sit in frames beneath the hatchways, allowing free movement, but when flooded, would float up into the space that needs sealing...
...some sort of light alloy, I s'pose, resting on enough foam to float it.
Doubtless, segmented accommodation plans would limit the freedom of movement and convenience of the crew...but given the disasterous freedom of movement by water, which open areas permit, surely permanently sealed sections make sense?
It's only below the waterline, I'm supposing, that this would be necessary - because if one of 20 sealed areas supporting no more than 5% of the total displacement each, is breached, then it's unlikely the ship will list (or go down by the nose) far enough, to endanger accommodation areas above the waterline...
It'd be a lot of extra steel, and lots of stairways. But fairly small beer, compared with the £19,000,000 excess (yes, really!) which was part of Concordia's insurance.
It seems such an obvious preventative to monumentally dreadful sinkings, I can't figure why ships aren't built this way. I guess I haven't thought of something.
Perhaps there ought, in the ideal 'unsinkable' ship, to be a whole sealable deck, at the waterline - ie, watertight doors in the floor - such that however bad the damage below the waterline, that portion of the hull can be isolated.
So, if the whole 'bilge' flooded, she'd still float...very deep in the water, and very vulnerable...but not an imminent total loss.
If I recall correctly, Titanic sank because incoming water drew the bow down, and nothing prevented its rising within the comparmentalised hull - so when the hull dipped under the increased displacement, the water flooded vertically, over the 'sealed' sections.
If the waterline had been sealable - by the deck at that point being built as strongly as the outer hull, with watertight doors enabling access except during inundation - then the flooded 'bilge' could scarcely have sunk the ship. No?
Maybe access hatches in the deck, could have 'floating' watertight doors - which wouldn't need operators - they'd sit in frames beneath the hatchways, allowing free movement, but when flooded, would float up into the space that needs sealing...
...some sort of light alloy, I s'pose, resting on enough foam to float it.
Greenheart
Well-Known Member
Hmmm...
...then again, if the whole hull beneath the waterline was flooded...a space c250m x c40m x c10m...that's approaching 100,000 tonnes of buoyancy, gone. So presumably she'd sink, even if the water could rise no further...
...but if the below-waterline area is made up of permanently sealed compartments, too...
...well, it's got to be worth model-testing. A sealable deck at the waterline, and permanently sealed compartments below the waterline.
Anybody know when the report on Concordia's loss is due?
...then again, if the whole hull beneath the waterline was flooded...a space c250m x c40m x c10m...that's approaching 100,000 tonnes of buoyancy, gone. So presumably she'd sink, even if the water could rise no further...
...but if the below-waterline area is made up of permanently sealed compartments, too...
...well, it's got to be worth model-testing. A sealable deck at the waterline, and permanently sealed compartments below the waterline.
Anybody know when the report on Concordia's loss is due?
Bajansailor
Well-Known Member
Dan, nobody cut any corners re safety or seaworthiness when they designed and built that ship.
The design had to be approved by the Classification Society concerned, and they all have extremely rigourous standards, and they would have kept a very close eye on her throughout the building process.
Passenger ships have to comply with a two compartment standard of sub-division - this means that the ship has to stay afloat if any two compartments in the ship are both flooded.
(Cargo ships, ie those that do not carry passengers, are generally only required to have a one compartment standard).
The ship designers have a graph called the Curve of Floodable Lengths, and by using this they can work out suitable longitudinal locations for the transverse watertight bulkheads. The aim is to try and get the biggest compartment allowable under the curve.
Because pax ships have to comply with a 2 compartment standard, the allowable sizes of the compartments at the ends are often smaller, as two flooded compartments at the bow or stern will cause the ship to trim down by the bow or stern a lot more than if the two same size compartments were amidships.
You have done a lot of hypothesising (? cannae spell it properly) above, but the bottom line is probably (IMHO) that when the rocks ripped the hull open after she came into contact with them, the resultant gash in the side of the hull spanned more than two compartments - I think various reports said it was at least 50 m. long.
If this is correct, then even if all of the watertight doors below the waterline were closed at the time of impact, then 3 (or even more perhaps) compartments would still have been breached, causing a huge loss of stability, and ultimately (in this case) capsizing - it is fortunate that this happened in relatively shallow water, although one would hope that if it had happened in deeper water she might have just assumed an extreme angle of loll and stayed there (but I would not want to bet on this happening).
A classic example of a vessel being stable at an extreme angle of loll was the car carrier Cougar Ace when she capsized - there is a good photo of her here.
http://en.wikipedia.org/wiki/MV_Cougar_Ace
She is floating in deep water here, not touching the bottom.
"OK, so why not make it a rule now that all future new build passenger ships have a 3 compartment standard instead?"
Well, this just would not be feasible.
At all.
For so many reasons.
Just imagine what the reaction would be if you proposed this to the IMO!
Or to ship owners, designers, and classification societies.
I don't know if a 2 compartment standard existed for pax ships when Titanic sank - probably not.
It must have taken a lot of effort to make it a requirement, and it probably only came into place as a result of major accidents (perhaps like Titanic?) happening.
Didn't the Titanic have watertight bulkheads but not full height?
If a compartment is breached, then some buoyancy is lost, and the ship sinks a bit deeper - if this is deep enough for the water to spill over the top of the 'watertight' bulkhead, then the situation quickly become much worse.
An analogy could be filling the sections in an ice tray from a tap with the tray at an angle under the tap.
You can fill a section perhaps half full, but because it is at an angle the water is already lapping over the top into the next section.
And even if the Titanic had a 2 compartment standard of sub-division, it is probable that more than 2 compartments were torn open when she came into contact with the iceberg - rather like the Concordia when she encountered those allegedly uncharted rocks.....
PRV Pete makes a very good point above re how all of the watertight doors should have been closed as a routine precaution when they were passing close to land - especially as they were intending to pass very close to this particular island.
In addition to the TSYT brig Stavros, most cruise ships will do just this whenever they enter leave port, are close to land, or in fog.
Probably when they are in shipping lanes as well.
And this is a major procedure to do each time, re closing all of the watertight doors on every deck that has them.
Although it is possible to close all of the watertight doors from the bridge immediately in an emergency by simply pressing buttons, they are not allowed to do this for the routine precaution closings, as there is then a very real risk that somebody could get caught in the door as it is closing.
So this means that various crew members are assigned to go and close all of the doors - to do this, they have to manually hold the closing button down until the door has fully closed (or opened).
And this takes time.
When all of the water tight door lights on the bridge display change from red to green, then they know that all are closed.
I have sailed on Stavros a couple of times as one of the volunteer crew, and one of my jobs was opening and closing the W/T doors whenever we were entering or leaving a port or anchorage.
She only has 3 watertight doors along her length on the accommodation deck, but they would each take a few minutes to manually close - I had ear plugs, as the siren was right next to my lughole while pressing the closing button......
The design had to be approved by the Classification Society concerned, and they all have extremely rigourous standards, and they would have kept a very close eye on her throughout the building process.
Passenger ships have to comply with a two compartment standard of sub-division - this means that the ship has to stay afloat if any two compartments in the ship are both flooded.
(Cargo ships, ie those that do not carry passengers, are generally only required to have a one compartment standard).
The ship designers have a graph called the Curve of Floodable Lengths, and by using this they can work out suitable longitudinal locations for the transverse watertight bulkheads. The aim is to try and get the biggest compartment allowable under the curve.
Because pax ships have to comply with a 2 compartment standard, the allowable sizes of the compartments at the ends are often smaller, as two flooded compartments at the bow or stern will cause the ship to trim down by the bow or stern a lot more than if the two same size compartments were amidships.
You have done a lot of hypothesising (? cannae spell it properly) above, but the bottom line is probably (IMHO) that when the rocks ripped the hull open after she came into contact with them, the resultant gash in the side of the hull spanned more than two compartments - I think various reports said it was at least 50 m. long.
If this is correct, then even if all of the watertight doors below the waterline were closed at the time of impact, then 3 (or even more perhaps) compartments would still have been breached, causing a huge loss of stability, and ultimately (in this case) capsizing - it is fortunate that this happened in relatively shallow water, although one would hope that if it had happened in deeper water she might have just assumed an extreme angle of loll and stayed there (but I would not want to bet on this happening).
A classic example of a vessel being stable at an extreme angle of loll was the car carrier Cougar Ace when she capsized - there is a good photo of her here.
http://en.wikipedia.org/wiki/MV_Cougar_Ace
She is floating in deep water here, not touching the bottom.
"OK, so why not make it a rule now that all future new build passenger ships have a 3 compartment standard instead?"
Well, this just would not be feasible.
At all.
For so many reasons.
Just imagine what the reaction would be if you proposed this to the IMO!
Or to ship owners, designers, and classification societies.
I don't know if a 2 compartment standard existed for pax ships when Titanic sank - probably not.
It must have taken a lot of effort to make it a requirement, and it probably only came into place as a result of major accidents (perhaps like Titanic?) happening.
Didn't the Titanic have watertight bulkheads but not full height?
If a compartment is breached, then some buoyancy is lost, and the ship sinks a bit deeper - if this is deep enough for the water to spill over the top of the 'watertight' bulkhead, then the situation quickly become much worse.
An analogy could be filling the sections in an ice tray from a tap with the tray at an angle under the tap.
You can fill a section perhaps half full, but because it is at an angle the water is already lapping over the top into the next section.
And even if the Titanic had a 2 compartment standard of sub-division, it is probable that more than 2 compartments were torn open when she came into contact with the iceberg - rather like the Concordia when she encountered those allegedly uncharted rocks.....
PRV Pete makes a very good point above re how all of the watertight doors should have been closed as a routine precaution when they were passing close to land - especially as they were intending to pass very close to this particular island.
In addition to the TSYT brig Stavros, most cruise ships will do just this whenever they enter leave port, are close to land, or in fog.
Probably when they are in shipping lanes as well.
And this is a major procedure to do each time, re closing all of the watertight doors on every deck that has them.
Although it is possible to close all of the watertight doors from the bridge immediately in an emergency by simply pressing buttons, they are not allowed to do this for the routine precaution closings, as there is then a very real risk that somebody could get caught in the door as it is closing.
So this means that various crew members are assigned to go and close all of the doors - to do this, they have to manually hold the closing button down until the door has fully closed (or opened).
And this takes time.
When all of the water tight door lights on the bridge display change from red to green, then they know that all are closed.
I have sailed on Stavros a couple of times as one of the volunteer crew, and one of my jobs was opening and closing the W/T doors whenever we were entering or leaving a port or anchorage.
She only has 3 watertight doors along her length on the accommodation deck, but they would each take a few minutes to manually close - I had ear plugs, as the siren was right next to my lughole while pressing the closing button......
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sailorman
Well-Known Member
[Didn't the Titanic have watertight bulkheads but not full height? ]
correct
correct
Fire99
Well-Known Member
I have to say that In my opinion, there is only so much you can protect against 'mechanically'. There are (supposedly) extremely well qualified crew on board to minimise risk.
In the case of the Concordia, the issue 'appears' that serious human error caused the accident and subsequent loss of life. There are only so many fail-safes that you can put in place and ultimately if the Captain chooses to effectively sail a ship into an Island, it's hard to 100% protect against it.
I guess if the ship was almost (and I hate to use the word) 'unsinkable', it would be prohibitively expensive and the accommodation / experience for the guests, would be compromised.
There will always be 'acceptable' risk in all that we do.
In the case of the Concordia, the issue 'appears' that serious human error caused the accident and subsequent loss of life. There are only so many fail-safes that you can put in place and ultimately if the Captain chooses to effectively sail a ship into an Island, it's hard to 100% protect against it.
I guess if the ship was almost (and I hate to use the word) 'unsinkable', it would be prohibitively expensive and the accommodation / experience for the guests, would be compromised.
There will always be 'acceptable' risk in all that we do.
