Oh Bugger

[Sunnyseeker]

A friend just sent this, and said he's not sure about an ocean crossing now?
http://news.bbc.co.uk/1/hi/sci/tech/3917539.stm


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[richardandtracy]

Rogue Wave

I'm surprised this is being presented as news.

The BBC did a Horizon programme last year about these waves called 'Rogue Wave'. The analysis presented in the program suggested that they grew up out of normal waves when the wave height approached 30ft. At this height the wave become unstable and effects normally only predicted for chaotic systems take over. In a rather unusual event the rogue wave can suck energy from the waves before & after and use this to build its height to 3 or 4 times normal with the same wavelength - giving a tall wave with a terrifying steepness. This then collapses after a short time as the phenomena is too unstable to last long. It's been suggested that the load inflicted on a vessel when the wave collapses is up to 100 tonne/m^2 (unless it's light enough to be pushed out of the way fast enough).

There was a thread on it here a while back, just can't remember when.

In any case, dont worry about it. It's unlikely that, should you find such a wave, you'll live to regret going out.

Regards

Richard.


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[Rick]

Funny this should appear today - on the Yacht-L list, Geoff posted the following URLs:
http://www.esa.int/esaCP/SEMOKQL26WD_index_0.html
(Obviously BBC journos are like Aussie jounos and willingliy pluck stories from the ether)
and
http://www.math.uio.no/~karstent/waves/index_en.html


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[snowleopard]

yes, but did the article mention where these waves are found? generally deep in the southern ocean and other places sensible yotties don't go.

the only known hot spot that would worry me is in the agulhas current.

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[richardandtracy]

One similar wave's been recorded in an F12 in the N. Sea (IIRC it was 82 ft crest to trough). The oil rig that recorded it had a permanently attached pressure recorder on one leg.

It seems that theses things can occur wherever the wave height exceeds 30ft, so in the middle of a severe storm is possible as well as areas where currents & winds oppose each other in a dramatic way.

Regards

Richard.


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[AndrewB]

Yes and ...

The continental shelf edge in Biscay is a suspect zone, the well known picture of a 100' wave hitting the <A target="_blank" HREF=http://www.viperalley.com/attach/data/1/137794-b.jpg>Recon-Randy</A> was on a normally benign offshore yacht passage route not far from Seattle, etc etc.

Lets face it, the sea is not always the conquered element that sometimes seems to made out here, and blue-water cruising does have risks that must be accepted.