Rogue waves.

[river runner]

I just checked out a new book from my library called 'The Wave', about giant rogue waves. Stories of freak waves over eighty feet, three times the height of the waves that came before and after, were long thought to be impossible, myths, tall sailor tales. Apparently they do happen, and scientists have to come up with new models to explain them. Perhaps you've heard of the Ocean Ranger. An oil platform built to withstand 110 ft. seas and 115 mile an hour winds. Thought to be indestructable by it's designers. Destroyed by a freak wave.

[yipster]

Check the search button above on roque waves
a few old treads explain them pretty well

[Tiny Turnip]

http://www.youtube.com/watch?v=DUn8WQ4Y1bM

The link above is to part 1 of 5 of the bbc documentary on freak waves. Parts 2-5 will show on the youtube page.

[jehardiman]

I professionally hate the terms "rouge", "freak", etc. “wave” applied to statistically significant seaway events. While they appear to occur randomly at any one location; that they will occur, and their size, is a statistical certainty. And it was only armchair “scientists” from the last century who used Airy and Stokes wave theory said they could not exist. They have been a fact in Naval Architecture since spectras were first used to describe the seaway over 60 years ago.

[Mr Efficiency]

Unless 'rogue' waves are a breed apart, I suspect they will come as a grouping of above-average waves, a phenomenon known as 'sets' to any experienced surfer or barred inlet boater.

[jehardiman]

Originally Posted by Mr Efficiency

Unless 'rogue' waves are a breed apart, I suspect they will come as a grouping of above-average waves, a phenomenon known as 'sets' to any experienced surfer or barred inlet boater.

Statistically significant seaway events are related to "the Three Sisters", but are formed by a much larger concentration of the many, many individual wavetrain maxima. While sets are fairly predictable, involving only a few dominate wavetrains, very large events that are 5 to 6 times the significant seaway height are much more rare.

[Tiny Turnip]

According to the documentary, they are, kind of, a breed apart. The thinking seems to be that generally, wave size follows a linear mathematical model, (Airy) which is adequate for most cases. This model also predicts that the chances of a wave three times the height of the norm for a particular set of conditions is virtually zero. (one would occur every 10000 years.) 'Anecdotal' evidence from sailors would suggest a much higher frequency of occurrence, but had normally been dismissed as exaggeration because this did not fit the model. When such a wave was *recorded* (plot above) by the North sea oil platform Draupner, in 1995, serious investigation began, including satellite radar scanning for 'abnormal' waves, and a much higher incidence of these was found. IIRC, the documentary quotes 10 in a couple of weeks, globally I think. These 'freak' waves, typically 3 times the height of their average neighbours, only seem to occur in already heightened sea states, with 'normal' waves around the 10-12 metre mark. (As I understand it, you don't get 6 metre 'freaks' in a 2 metre sea state.) They are isolated events. Furthermore, they have the same wavelength as the normals, so they are much, much steeper, and tend to break. A mathematical model developed from quantum physics seems to fit. The 'freak' somehow robs energy from its immediate neighbours, so the waves immediately next to them are shorter than the norm, and they also develop correspondingly deeper troughs either side.

Local conditions, currents etc can increase the frequency of occurrence.

The pressure they can exert is immense. 100 tons per square metre is quoted, c/w 6 tons per square metre for a 12 metre wave, accounting for the catastrophic damage to ships seen not infrequently when struck by such a wave.

That's, broadly, what I got from the documentary. Its edited and voiced with the usual melodramatic gravitas, but its fairly compelling viewing.

An interesting article below, too, which goes on to explore the possibility of 'freak' optical waves.

http://skullsinthestars.com/2010/07/...he-laboratory/

[cyclops2]

On a 1 hour special. Quantium Physics is describing the stealing of energy on both sides of the Rouge Wave.
The German satillite DOES find the Rouges around the world & sends warnings to ships where they are located.
Great piece of research. They truly are Rouges. No repeat patterns according to the Germans radar sweeps. Just horrible bad luck to be attacked by a 30 meter one. They do rip bows off of super tankers.

They sink 1 or 2 container ships a year. Reason the Pacific has a massive debry field floating in it.

[Mr Efficiency]

These extreme waves must have cleaned up an awful lot of vessels over the centuries, no doubt accounting for many unexplained losses. The sea is not a place to be getting complacent, I never feel 100% relaxed on the open sea, you always need to be on alert for the unexpected.

[Tiny Turnip]

from the linked article:

The existence and origin of freak waves is not simply a question of academic interest; between 1969 and 1994 at least 22 supertankers are thought to have been sunk by freak waves, with many associated fatalities**.

[cyclops2]

And we thought Pirates caused missing pleasure boats ??

[eyschulman]

The reason more is known about these waves is due to satellites with radar units that can find track and document hight. Not as rare as people thought.

[Leo Lazauskas]

Originally Posted by cyclops2

They sink 1 or 2 container ships a year. Reason the Pacific has a massive debry field floating in it.

No, that's not the reason.

[cyclops2]

Tiny Turnip

Neat name.

[cyclops2]

If you read what is floating in the mess. You will see it is floating wreckage from container ships............Nike sneakers, Containers, etc.

The trees and Sunami stuff will rot & sink. Man made plastic floats forever.