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Smaragdadler · 09-26-05, 04:43 AM

I remember watching a TV-documentation some time ago about Kaventsmanns (aka 'freak'- 'killer'-, 'rogue', 'giant'- or 'monster'-waves'), who can destroy a ship instantly. (*not* Tsunamis - these are a result of earthquakes, volcanic eruptions, underwater landslides, or asteroid impacts which shake the sea floor - they have nothing to do with wave-accumulation, currents and storm) They said that till now it was thought, that this monsterwaves are only fairy-tales by old seamen. But there was a project of some scientist who examined lots of satalite images and they have found them. They said that it occurs not too seldom (in the average two every day somewhere on this planet). Basicly this 'killer-waves' build up randomly from other big waves in heavy storms, but there is a special kind who can occur in calm see. So you have a storm with the biggest waves of a high of say 12m and suddently a 25m monster comes your way. The ones in calm see occur out of nowhere and don't last for a long time, only minutes.

This are the areas where there is a higher chance for Kaventsmanns because of the strong currents. But they can basicly build up everywhere.

The left picture shows a freak wave from the ESA-data. The right picture was taken on the oil freighter Esso Languedoc outside the coast of Durban (1980). The man who took it, Philippe Lijour, estimated the mean wave height when this occurred to be about 5-10 m. The mast on the starboard side is 25 m above the mean sea level. The wave approached from behind and broke over deck, but caused only minor damage.

There seem to be three kinds of freak-waves (which have been reported since centurys, but where not taken for real by scientist for long time):

1) the 'basic' Kaventsmann: a high relative fat wave, which can whirl ships and sink them by throwing them on their side...

2) The Three Sisters: 3 waves of relative middle high, who come with high speed one following the other. Ships can hardly evade them and can not drift over them...

3) The White Wall: An extremly steep 30m (and above!) high wave with a front lenght of up to several kilometers (!!!) It is extremly unstable and vanishes after only some minutes. But if you should ever see such a thing heading to you for real, - just start to pray. It simply crushes all solid objects in its way... (some 100t per quadratmeter)

This three images where choosen by me (Smaragdadler) and may not even show 'the real thing'. The 'white wall'-pic on the far right is defenitley not genuine, but taken from a movie capture...But it will give you the 'idea' (platonic style)....

Till now there is no really solid scientific explanation for explaining this waves, because with standart wave-building models they should occur only once every 10000 years...

Tsunamis are not dangerous in blue water because they are under the surface and become only desastrous when they reach the shore. Freak waves on the other hand are only short living and build up far away from shore. This is why, they where only seen by true sailors for long time, and not many have survived them to tell about it. They are now also believed to be one possible cause for 'vanished' ships, nobody has seen again... Every year around 100 Ships in the world disapear and there is not so much investigation like after an airplane crash.

7m waves in storms is usual, 12m in heavy storms is ok. Till now ships where constructed to face something to 15m waves. In the average you have one short-lived freak-wave per 150,000 km2 ocean. This is still an extremely rare occurrence in its own right. But they are believed to become more 'common' in future, because of climatic change caused by mankind, there will be more storms...

[joke] Ehrm. So, please, please, please Sonalyst - can you...(etc.pp.)

Imagine:

Dangerous Waters 5 - The Wave War
[/joke]

21 July 2004
Giant wave produced with a hydaulically-powered wave generator in the Giant Wave Tank in Hannover in 2002. As part of the MaxWave project, a team at the Technical University of Berlin worked on simulating their production. Their work guided by computer modelling, the team found rogue waves appear to be formed when slow-moving waves are caught up by a succession of faster waves moving at more than twice their speed, then merge together.

Credits: Technical University of Berlin
http://www.esa.int/esaCP/SEMOKQL26WD....html#subhead7

-------------------------------
Links in German:
http://de.wikipedia.org/wiki/Kaventsmann
http://www.br-online.de/wissen-bildu...hung/index.xml
http://weltderwunder.rtl2.de/wdw/Nat..._Killerwellen/

Here is an article in English-language:
http://www.esa.int/esaCP/SEMOKQL26WD_index_0.html

Wikipedia in English:
http://en.wikipedia.org/wiki/Freak_wave

Freak waves, rogue waves, extreme waves and ocean wave climate:
http://www.math.uio.no/~karstent/waves/index_en.html

09-26-05, 04:43 AM	#25
Smaragdadler XO Join Date: Apr 2005 Location: Thuringia Posts: 429 Downloads: 16 Uploads: 0	I remember watching a TV-documentation some time ago about Kaventsmanns (aka 'freak'- 'killer'-, 'rogue', 'giant'- or 'monster'-waves'), who can destroy a ship instantly. (not Tsunamis - these are a result of earthquakes, volcanic eruptions, underwater landslides, or asteroid impacts which shake the sea floor - they have nothing to do with wave-accumulation, currents and storm) They said that till now it was thought, that this monsterwaves are only fairy-tales by old seamen. But there was a project of some scientist who examined lots of satalite images and they have found them. They said that it occurs not too seldom (in the average two every day somewhere on this planet). Basicly this 'killer-waves' build up randomly from other big waves in heavy storms, but there is a special kind who can occur in calm see. So you have a storm with the biggest waves of a high of say 12m and suddently a 25m monster comes your way. The ones in calm see occur out of nowhere and don't last for a long time, only minutes. This are the areas where there is a higher chance for Kaventsmanns because of the strong currents. But they can basicly build up everywhere. The left picture shows a freak wave from the ESA-data. The right picture was taken on the oil freighter Esso Languedoc outside the coast of Durban (1980). The man who took it, Philippe Lijour, estimated the mean wave height when this occurred to be about 5-10 m. The mast on the starboard side is 25 m above the mean sea level. The wave approached from behind and broke over deck, but caused only minor damage. There seem to be three kinds of freak-waves (which have been reported since centurys, but where not taken for real by scientist for long time): 1) the 'basic' Kaventsmann: a high relative fat wave, which can whirl ships and sink them by throwing them on their side... 2) The Three Sisters: 3 waves of relative middle high, who come with high speed one following the other. Ships can hardly evade them and can not drift over them... 3) The White Wall: An extremly steep 30m (and above!) high wave with a front lenght of up to several kilometers (!!!) It is extremly unstable and vanishes after only some minutes. But if you should ever see such a thing heading to you for real, - just start to pray. It simply crushes all solid objects in its way... (some 100t per quadratmeter) This three images where choosen by me (Smaragdadler) and may not even show 'the real thing'. The 'white wall'-pic on the far right is defenitley not genuine, but taken from a movie capture...But it will give you the 'idea' (platonic style).... Till now there is no really solid scientific explanation for explaining this waves, because with standart wave-building models they should occur only once every 10000 years... Tsunamis are not dangerous in blue water because they are under the surface and become only desastrous when they reach the shore. Freak waves on the other hand are only short living and build up far away from shore. This is why, they where only seen by true sailors for long time, and not many have survived them to tell about it. They are now also believed to be one possible cause for 'vanished' ships, nobody has seen again... Every year around 100 Ships in the world disapear and there is not so much investigation like after an airplane crash. 7m waves in storms is usual, 12m in heavy storms is ok. Till now ships where constructed to face something to 15m waves. In the average you have one short-lived freak-wave per 150,000 km2 ocean. This is still an extremely rare occurrence in its own right. But they are believed to become more 'common' in future, because of climatic change caused by mankind, there will be more storms... [joke] Ehrm. So, please, please, please Sonalyst - can you...(etc.pp.) Imagine: Dangerous Waters 5 - The Wave War [/joke] 21 July 2004 Giant wave produced with a hydaulically-powered wave generator in the Giant Wave Tank in Hannover in 2002. As part of the MaxWave project, a team at the Technical University of Berlin worked on simulating their production. Their work guided by computer modelling, the team found rogue waves appear to be formed when slow-moving waves are caught up by a succession of faster waves moving at more than twice their speed, then merge together. Credits: Technical University of Berlin http://www.esa.int/esaCP/SEMOKQL26WD....html#subhead7 ------------------------------- Links in German: http://de.wikipedia.org/wiki/Kaventsmann http://www.br-online.de/wissen-bildu...hung/index.xml http://weltderwunder.rtl2.de/wdw/Nat..._Killerwellen/ Here is an article in English-language: http://www.esa.int/esaCP/SEMOKQL26WD_index_0.html Wikipedia in English: http://en.wikipedia.org/wiki/Freak_wave Freak waves, rogue waves, extreme waves and ocean wave climate: http://www.math.uio.no/~karstent/waves/index_en.html