What a herald of free enterprise!
The world’s largest cruise liner on Friday began its maiden voyage to Florida, gliding out from a shipyard in Finland with an amphitheater, basketball courts and an ice rink on board.
The 16-deck Oasis of the Seas spans 1,200 feet (360 meters) from bow to stern. Its 2,700 cabins can accommodate 6,300 passengers and 2,100 crew.
Commissioned by Royal Caribbean International, the ship cost euro1 billion ($1.5 billion) and took two and a half years to build at the STX Finland Oy shipyard in Turku, southwestern Finland.
The liner has four swimming pools, volleyball and basketball courts, and a youth zone with theme parks and nurseries for children. There is also an ice rink that seats 780 spectators and a small-scale golf course.
One teensy-weensy little thing they forgot:
STABILITY!!!
Do you think it’s naughty of me to run this again?
If that one rolls, imagine what the monster will do? Wonder why this doesn’t cross the designers’ minds? Ho hum.
Filed under: Leisure, travel & sport, Society & human issues
Noooooo
I never liked the ferry crossing to France or Ireland……thanks for making my mind up for me when it comes to a cruise!!!!!
That’s Poseidon Adventure stuff mate!!!!
That’s no Contessa 32.
Well, ship stability is definitely not my field. However, James seems to have somewhat tempted me, so I’ll have a go with a few tens of minutes of looking in Wikipedia and some vague recollections of the Herald of Free Enterprise disaster.
Wikipedia on ship stability: http://en.wikipedia.org/wiki/Ship_stability
And the linked Wikipedia article on center of buoyancy: http://en.wikipedia.org/wiki/Center_of_buoyancy
And, for the record, on the Herald of Free Enterprise: http://en.wikipedia.org/wiki/Herald_of_free_enterprise
Unfortunately nothing useful found so far on the ship architecture of the Oasis of the Seas: only how wonderful will be the passenger experience.
My very quick interpretation. Ships are designed to be stable. Unless the cargo shifts, they flood or some other disaster such as really extreme weather strikes, they are stable enough.
To mitigate against various disasters, and flooding, bulkheads (both fore-and-aft and across the ship) are usually installed. These much reduce the risk to stability from flooding. Various stabilisers (mechanical and/or hydraulic weight-shifting/pumping mechanisms are also used on larger ships), both to reduce risk to stability (generally and in emergency) and to improve passenger/crew comfort.
The Herald of Free Enterprise was a ship type (roll-on-roll-off ferry) at greater risk because of the lack of bulkheads necessary for its designed function. It rolled over because it flooded. It flooded because the main loading doors were left open. The doors were left open because of a combination/sequence of human errors.
The relevance of the Herald of Free Enterprise disaster to the risk of rolling of the Oasis of the Seas is very small, at least in my humble opinion and on the basis of evidence presented so far by James. But I know nothing about ship stability, apart from what the last half hour (plus a bit of physics) has taught me.
James will now make me look uninformed, by producing that bit of backup material held, in reserve to support the next stage of his argument.
)
Best regards
Charles roring [naval architect] writes:
He concludes from that that the modern cruise ship is stable. Now, anyone with a knowledge of basic physics knows that putting swimming pools on top decks of a boat already 16 stories high but about twelve across is fine in flat seas and with stabilizers.
Any sailor involved with hydrofoils can tell you that they don’t always work because the sea is not flat. It has this annoying tendency to make waves and those waves come at you from different directions. Look at the ship in the vid – its stabilizers are of no effect in a beam sea. Layman hear the word stabilizers and think oh goody – well, that’s all right then.
What are they though? They are gyroscopically controlled devices which create opposite forces to roll. Now Nigel, I’m the first to admit that in calm and medium seas, they work well and ships tend to avoid the bad weather as far as possible. However, as a commenter called Dreadnought wrote on a naval site:
The thing is, there is no reason to suppose, particularly up this end of the earth, that you’re not going to hit rough weather. Have you ever listened to the shipping forecast? What’s worse, the ship is holding a course and in fact cannot immediately alter its course at that size so we get the breaching effect which you saw in the vid. You were right to slap my wrist over the HofFE because she was a different craft, with different problems. However, she was also much lower in the water than this craft and not made of the ultralight material.
In the end, common sense, not just the technical stuff above should tell you that that craft – have a good look at it, with sloshing swimming pools on the top deck, in even a twenty foot swell, is going to set up a rolling moment which, true – the stabilizers will counter but then the roll becomes progressively more, even if the sea does not noticeably increase in force.
This is unstable enough to be a worry.
The thing which worries me most is that the architects have done what they thought was very clever – thumb their noses at maritime physics and work on the principle of equals and opposites – basic physics. Any small boat designer follows certain principles about centre of buoyancy, centre of lateral stability, draught and so on. There are rules of thumb in this ship which are being ignored, on the principle that they can counter that.
Yes they can – in the sense that someone on one end of a seesaw counters the person at the other end. If one has greater mass, he moves towards the fulcrum. On a boat, computers control this algorithm and thus the boat remains stable. However, the nature of sea, wind and tide produces conditions which add to the calculation and cannot be second guessed – the Michael Fish principle.
It’s the danger of these altering the equation which is the real worry, in the light of the arrogance of the architects who decided to design and build this floating tower of Babel.
We’re you’re coming from, Nigel, dear sir, is the implicit belief in guild professionalism. These lads must know their stuff – ipso facto, the ship is safe. I’m afraid the motivation is not ship’s safety but luxury accommodation for as many paying passengers as they can get in and remember, these people are also up above.
The sea and the wind beg to differ and are not particularly interested in the odds of a disaster.
I respond to James’ comment of October 31, 2009 at 16:22.
James quotes, I think approvingly, Charles Roring [naval architect] on criticising swimming pools 16 decks above sea level. I cannot dispute this criticism. That is except on the grounds that natural sunshine is, presumably, valued by the customers more than the artificial light available on lower decks, and even (with no worse light) in the very bowels of the ship: a good place for all that extra water. That is, for the 16th deck swimming pool, providing there is sufficient additional ballast to avoid raising the centre of gravity (which, of course) raises ship running costs. There might also be some other safety disadvantages, though I suspect they are second-order effects only.
However, James finishes with “We’re you’re coming from, Nigel, dear sir, is the implicit belief in guild professionalism. These lads must know their stuff – ipso facto, the ship is safe. I’m afraid the motivation is not ship’s safety but luxury accommodation for as many paying passengers as they can get in and remember, these people are also up above.”. This, I take as a criticism of the whole class of naval architects, to say nothing of other guilds as well.
Thus we have a disagreement. I do, on the whole, agree with trusting one’s life to expert engineers: I’m an engineer or sorts myself, so of course I probably would. But there is no choice in this modern world. We live longer and die later (and more cosily because of engineers, including those medical engineers called doctors). And in between we live more pleasant lives and generally have a better time.
I am often (highly) critical of engineers who compromise true engineering for additional short-term profit and/or significantly higher risks to customers and others, and I think James knows that, at least partially. James and I have ‘crossed’ on these matters before, IIRC initially on high-speed trains. I do understand his concerns. They are on what are, both seemingly and truly, the use of engineering and technology at the boundary of what is safe. However, things at the boundary must be done: otherwise there is no progress. And most of the time, in fact IMHO nearly all of the time, it works out OK. I also suspect that, where there are problems, the majority are with operational procedures that are not compatible with the engineering analysis of risks. That is, most likely, down to human-to-human communications problems and non-engineering business pressures. Just how does one lay the blame at the door of engineers when, more often than not I suspect, the final decision is with financial and business managers: very likely those less well trained in the proper managing of risk.
On risk, I am very keen on cost-benefit analysis, in Bayesian risk analysis terms (in so far as it can be done), in assessing risks to life and limb. However, this does require that we place a value on life versus a value on benefit: convenience, each man-hour, etc. Many people are unhappy with this sort of equivalence, and I have some tolerance for that view, thought little sympathy in practice. This is because we make decisions on what risk to accept all the time, whether or not we think of it in terms of cost-benefit analysis, Bayesian risk analysis, etc. However, no matter how we think about such risk assessment, there is an interpretation of the decisions we make in terms of such cost-benefit analysis and/or Bayesian risk analysis. From that one can look back and determine relative values on life, injury, etc versus convenience, a man-hour’s value, etc. It is untidy and incomplete, admittedly. However, there always is some implicit balancing of these things.
Given my upbringing in science and engineering, I think it better to tackle such things head-on, rather than beating about the bush with much gnashing of teeth. I also think is is better to rely on expertise, combined with practical knowledge of the real world and human society. Average gut-feel or political or journalist induced ‘mass hysteria’ are far worse determiners for us, of what we should decide.
That’s enough for now, I think. I might post more on James’ response later.
Best regards
Concerning the video of the blue and white cruise liner in distress in heavy seas, is there any information on which ship, where and when this occurred? And the provenance of the video itself?
Best regards
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