Rogue Waves
- Thread starter Rodney
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Bjorn
Off Topic
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And even with a membership it's a pay per information service. However, the numbers I've quoted (26 ships of over 200 meters have been declared a "total loss" over the past five years) are from Lloyd's - pay to check if you want to.
Sure - it is possible, but we have no information leading us to believe it is true. Further, we have no information about ships over 200 meters being sunk/lost because of freak waves.
We have another source saying "in the past two decades, freak waves are suspected of sinking dozens of big ships" .... "dozens", not hundreds, "big ships", not ships over 200 meters in length, "suspected" ....
Do you realize how small a percentage of the ships in the world are that size?
Further, did you read the information below at all?
There had been 142 ships of that size lost at sea in that time frame.
All with clear, known causes.
Main culprits were wars/air forces.
Further, I looked into information about big ships lost in 2004 and what caused the losses:
I have quoted the chairman of Intertanko, who says "It's simply not true".
Since you brought up the IMO, I went through their list of "very serious" and "serious" casualties for the year 2000. Reading through it, as I'm sure you will, keep in mind that a ship more than 200 meters long will be, say, 25,000 tons or more. Here is the info about those big ships from the first page, I challenge you to do your own investigation for the other pages ....
12/12/2000, oil tanker, collision
21/04/2000, livestock carrier, fire
26/02/2000, OBO carrier, explosion
27/05/2000, oil tanker, fire and explosion
01/11/2000, container ship, "other", but the weather was nice
08/02/2000, OBO carrier, fire
21/04/2000, livestock carrier, fire
26/02/2000, OBO carrier, explosion
27/05/2000, oil tanker, fire and explosion
01/11/2000, container ship, "other", but the weather was nice
08/02/2000, OBO carrier, fire
Finally, maybe you could stop wishing it was true, or telling me/us how we haven't posted sufficient evidence against it ... just post the evidence you have for your case. In addition to Rosenthal, who (honestly) exaggerated his case and never posted any evidence for his numbers (or, if he did, please post them here).
I've gone through a lot of lists of sunken ships and looked at the reasons why they went down. Why don't you do the same? Too much work? Worried about what you'll find?
Correa Neto
Philosopher
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There are figures avaliable at those and other papers at the workshop. Perhaps it would be a nice time for you to check them. Besides curing insomnia, it may also cure misinformation.Most of those papers are a good cure for insomnia.But let me ask you this: Are you saying that the erroneous models oceanographers used for years allowed for "extreme" waves, but not for "rogue" waves? If so, what was the maximum wave size those models allowed for?
The point I made was: "We know that rogue waves cause ships to sink year in and year out." I then cited the figure of 200 ships of more than 200 meters that have reportedly sunk over the past 20 years and argued that it's likely that at least 10% of those ships, or 20 in total, would have sunk due to rogue waves. Let's assume, however, that the 200 figure is an exaggeration. Fine. We now have documented proof that 3848 ships were lost just during 1985-2000. That works out to more than 240 per year. So, if even 1% of those losses were due to rogue waves, my statement that "we know that rogue waves cause ships to sink year in and year out" would be accurate. Now, admittedly, it is not confirmed that 1% of those losses were due to rogue waves, but based on the fact that we now know that rogue waves occur every day and that anecdotal evidence strongly indicates that such waves have sunk or damaged a number of ships, it's very likely that 1% is conservative in the extreme.
So the bottom line is, at this point, it's not that big of a deal to me whether 200 ships of more than 200 meters have sunk during the past 20 years. However, I still would like to know where that figure came from.
is not the same as
is it? And
don't add to the confidence level, do they?
The fundamental issue is whether, prior to 1995, oceanographers' models accounted for extreme waves. I don't see anything in the papers that you've cited that indicates they did.
Depends on your perspective. I'm confident that my statement that "we know that rogue waves cause ships to sink year in and year out" will be proven accurate.
No, it certainly will not.
"Rogue waves cause ships to sink year in and year out" might conceivably be proven accurate, though there's little evidence to support it and rather a lot against. I consider the odds to be vanishingly small but they are nonzero.
You cannot, however, state that "we know" this when available evidence demonstrates clearly that "we" do not know any such thing.
Correa Neto
Philosopher
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Have your really read them? Read carefully and you will find.
Now, are you talking about extreme or rogue waves?
If you are talking about extreme waves, then the answer is: Oceanographers knew about them and studied them. Insurance companies and engineers took them in to account. For the third or fourth time I point you to http://www.ifremer.fr/web-com/stw2004/rw/fullpapers/haver.pdf, where you can be able to check it by yourself.
At http://www.ifremer.fr/web-com/stw2004/rw/fullpapers/kjeldsen.pdf you will also find data on the sinkings known or suspected to be the result of rogue waves. You will also find diagrams showing that the shape is a key factor.
The fundamental issue, if you are really talking about rogue or freak waves, is when oceanographers obtained the tools to investigate the phenomena. And again, if you read the papers from the 200 workshop, you will see that (a) your claim about reports not being seriously taken is incorrect and (b) some papers were based in data collected since 1984. Its not trivial to study such phenomena, as you seem to think.
No goalposts necessary. He plays in one of those leagues where they don't keep score so no one has hurt feelings. [Goalposts imply scoring implies a factually provable difference between the winner and the loser]
So were any of the 3848 ships lost during 1985-2000 the result of a rogue wave?
Depends upon your interpretation of the evidence.
I don't know. As you've been told over and over again, the burden of proof is upon you, the one making the extraordinary claim, not me. You tell me. I'll expect proper, complete evidence to back it up.
No it doesn't. Please re-read my previous post until you understand the difference between claiming that "x is true" and claiming that "we know that x is true."
The first paper states: "Herein we will define freak waves as typical members of population being defined by physical mechanisms well beyond those underlying 'classical' extreme waves. These types of extreme wave events are not explicitly accounted for in the design process. If such a population exists, it may challenge present design recipes if it significantly affects wave properties (crest heights, wave heights, wave steepness) at a given site corresponding to annual exceedance probabilities of 10^-3 – 10^-5."
If such a population exists? We know that rogue waves exist, and so the author seems to be trying to define a sub-class of rogue waves. Fine by me, but the fact still remains that standard oceanographic models did not account for rogue waves prior to 1995.
The second paper concludes:
• There is a need to increase survivability of modern ships, in such away that a damaged ship with a heeling angel can sustain impacts from large waves and still maintain a marginal dynamic stability.
• The rules and requirements of ship dynamic stability is clearly insufficient. Not only the area below the GZcurve should be taken into account but also the displacement of the ship and the mass moment of inertia given as the radius of gyration. This applies both to intact stability criteria and to criteria for damaged stability.
• High impact forces caused by extreme waves breaking on the superstructure of ships and should be considered. In particular large windows are weak points.
• Dynamic pressures from large amounts of water on deck should be considered. Hatch covers on bulk ships are weak points and should have the same strength as the ship hull.
• A better education of ship officers is needed. In particular we need a better education in ship handling of intact and damaged ships in severe weather conditions. Better guidelines should be given to ship officers regarding the choice of the right time to evacuate a damaged ship, and the time needed to evacuate in severe wave conditions.
• The “tsunami wave model“ reversed in the time domain was found to be a successful mathematical technique for modeling of a 3-dimensional freak wave.
• A risk management model with the scope to avoid capsizing in freak waves in a given sea area can be established as a joint probability model for encounter of a wave with an abnormal wave height and at the same time an abnormal crest front steepness. A successful forecasting of freak waves is already established.
• An international standard is needed for hydrodynamic laboratories performing capsizing experiments with ships and platforms in breaking waves and extreme non-breaking waves. This standard should be based on laboratory measurements of wave kinematics.
So the second paper concludes that current ship design is inadequate to account for rogue waves and should be corrected.
Why is this an "extraordinary claim"? Do you think it's more likely that ships sink in storms in which there are 5-meter waves or 25-meter waves? I think the main problem here is that shipping companies don't want to admit that their ships are not designed to withstand rogue waves and try to slough off losses on "bad weather" without a thorough investigation. However, as the Kjeldsen article that Correa cites notes about one case in which there was a Court of Inquiry: "'ANITA' disappeared completely at sea with the whole crew and no emergency call was ever given. The Court of Inquiry then concluded that the loss can be explained by an event in which a very large wave suddenly broke several hatch covers on deck, and the ship was filled with water and sank before any emergency call was given. The wave that caused the loss of 'ANITA' was probably a freak wave."
Okay, I don't "know" that "rogue waves cause ships to sink year in and year out", but based on evidence that's been developed in recent years, it's about 99% certain.
politas
Pirate King
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So your claim that scientists ignored rogue waves would be false, then?
Because it contradicts evidence, as you've been shown repeatedly.
Ah, a probability! Please show your calculations or wipe that brown stuff off the number.
Hardly. The great majority of oceanographers wrote rogue waves off as exaggerations until the evidence became irrefutable.