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Catalina/Capri 25/250 Sailor's Forums

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The source of Freak Waves

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Steve Blackburn
Master Marine Consultant

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Canada
1091 Posts

Initially Posted - 03/09/2009 : 03:10:49

I thought these were folklore, and so did the scientific community for a long time. However such occurrences do happen more often than one might think. I stumbled on a series of highly interesting BBC videos that proved me wrong. The linear model dictates that even in a fierce storm where the average wave height might be 12 meters (40 feet) that the chance of hitting a 30 meter wave (100 feet) is practically ZERO. Using the linear model the chances of hitting such a wave is 10 to the -5, which is 0.0001%. To put things in perspective that means that a freak wave comes once every 10,000 years.

However they do occur. The combination of wave direction against the current is what gives life to these monsters. In fact there are 2 kinds of waves, the ones who do follow the stable linear model and the unstable non-linear waves that feed off the energy of other waves around them. A few places in the world are known to have the right conditions to summon these beasts. Fortunately most of our cruising grounds are nowhere near there.

You may view the high res videos on my web site:
http://vidanova1.mysailboatblog.com/2009/03/09/freak-waves/

Steve Blackburn, Calgary, AB
C250WB - 1999 - Hull 396

Edited by - Steve Blackburn on 03/09/2009 03:17:32

Derek Crawford
Master Marine Consultant

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USA
3321 Posts

Response Posted - 03/09/2009 : 12:01:32

A little long - but fascinating!

Edited by - on

delliottg
Former Mainsheet C250 Tech Editor

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USA
4479 Posts

Response Posted - 03/09/2009 : 12:16:38

I watched a National Geographic (I think) special on this just a few weeks ago, they identified the eastern coast of South Africa as one of the most likely places for a rogue-non-linear-model wave to occur, and with frightening frequency. They mentioned the 10,000 year concept as well, and showed satellite photos of rogue waves out in the Pacific Ocean, that popped up for no apparent reason. Apparently shipping companies have directed their captains to avoid the east coast of SA & stay further out to sea. Fascinating stuff to watch, but would not want to experience one first hand. I've been in very heavy seas in the Mediterranean, English Channel & North Sea, but never seen a rogue wave, and hope that I never do.

Edited by - on

Nautiduck
Master Marine Consultant

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USA
3704 Posts

Response Posted - 03/09/2009 : 21:07:32

Excellent, thanks for posting that. Come to think of it I like sailing on a lake!

It would be interesting to know how far those non-linear rogue waves travel. Do they just rear up and then crash down or do they travel for a long distance?

Edited by - on

Steve Blackburn
Master Marine Consultant

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Canada
1091 Posts

Response Posted - 03/09/2009 : 23:23:15

From what I read they are short lived. 1-2 minutes only. Lots of math involved in trying to create a model, but I like to simplify things. Basicaly freak waves happen when a storm is brewing and the winds are going in the opposite direction of the current. So that's what you have to watch out for when cruising. Researchers are currently trying to map freak waves covering more than a decade of observations. From what I have seen so far, such waves happen mostly on the higher latitudes aroud the South African tip and northern baltics which is no where near where I plan to cruise.

Edited by - on

DaveR
Master Marine Consultant

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USA
2015 Posts

Response Posted - 03/10/2009 : 07:58:05

Really interesting stuff Steve, thanks for the post!

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ruachwrights
Captain

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USA
258 Posts

Response Posted - 03/10/2009 : 14:31:40

According to a television program I was watching (discovery I think) waves like this can also occur in the Bermuda

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ruachwrights
Captain

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USA
258 Posts

Response Posted - 03/10/2009 : 14:32:52

According to a television program I was watching (discovery I think) waves like this can also occur in the Bermuda Triangle area.

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dmpilc
Master Marine Consultant

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USA
4593 Posts

Response Posted - 03/10/2009 : 15:46:58

Captivating stuff. Thanks for posting it. Really scary. Hope one never comes close to shore.

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Steve Blackburn
Master Marine Consultant

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Canada
1091 Posts

Response Posted - 03/10/2009 : 16:20:17

I don't think they would come to shore because it seems they need a certain depth to sustain the energy. You know, I was just thinking of the Bermuda triangle that might be an area. Lots of currents and high winds there right? Once they have mapped out the occurences we'll know better.

What is really scary is that usually there is a hole in the water of about 40 feet down before the wave, then a rising wall of 60-100 feet.

By the way this subject is one of them that I will NEVER discuss with my wife. That would be the end of my dream to cruise the oceans with her. Again I think this can be managed by not going out in certain conditions, but I know very well that a storm can brew up pretty quickly. The purpose of this post is not to scare you but rather to know how things work to make it less scary!

Edited by - Steve Blackburn on 03/10/2009 16:21:05

ruachwrights
Captain

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USA
258 Posts

Response Posted - 03/10/2009 : 16:57:31

Amen to that Steve. The fact is, sailing is probably more safe than driving. Anyway what is safe? Once when I was swimming across a lake alone after a run I started to cramp up. I realized that forces of nature can take us out pretty much anytime. And even in our homes, forces of nature can "come-a-knockin'". The featured article of the latest edition of Scientific America about non-local physics and entanglement is pretty intriguing- if not world-view shaking. If I understood it correctly a sub-atomic particle on one end of the galaxy can directly influence a sub-atomic particle on the other side of the galaxy even though no intervening particles are moved. Sailors know that anything can happen at anytime- and that even a lake can become unpredictable as if by magic. That's part of the romance.

But back to the subject of rogue waves; one of the more interesting scenarios I saw on the television program I was watching, is when a large wave breaks around an island. When the wave joins together again at the place where the wave was broken-at a point now beyond the island, the force of the two fronts coming together can make the wave suddenly much larger. This is not exactly a rogue wave per-se but it can be pretty dangerous.

Edited by - on

Steve Blackburn
Master Marine Consultant

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Canada
1091 Posts

Response Posted - 03/10/2009 : 17:15:46

Ah yes, you are entering the realm of Quantum Physics here a subject I particularly relish! The theory of Quantum Entanglement. For example if you split an entangled pair of a photon particles and send them a long distances apart they will still be entangled and affect each other. One "knows" what the other is doing no matter the distance. A recent experiment in Geneva reported that at 11 miles apart the 2 particles communicated with a reaction time of 300 trillionths of a second. That is 10,000 times the speed of light. So imagine if you could have 8 of these entangled particles both in 2 separate boxes you could pass 8bit information (just like computers) at insane speeds. A heck of a modem. Applications range from space exploration to telecommunications here on earth. Imagine watching and controlling a Mars rover in real time rather than the the current 10 minutes a signal takes to travel the distance between Earth and Mars. Line of sight doesn't seem to matter either! Now that is the future of our Marine Radios! :-)

Edited by - Steve Blackburn on 03/10/2009 17:16:39

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 03/10/2009 : 20:32:57

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by ruachwrights
 ...when a large wave breaks around an island. When the wave joins together again at the place where the wave was broken-at a point now beyond the island, the force of the two fronts coming together can make the wave suddenly much larger.<hr height="1" noshade id="quote"></blockquote id="quote">This was true in the big tsunami a few years ago--a couple of islands had the greatest damage at the midpoint of the "lee" shore from the tsunami. It's the same principle as the standing waves you can often see where waves reflect off a seawall, such as in an inlet. When waves intersect (such as one wave intersecting one like it that just bounced off a wall), the amplitude of the resulting wave (trough to crest) is additive.

That leads me to a theory I've had on "rogue waves" for some time... that they are the result of a confluence of waves from separate weather systems that might be hundreds or thousands of miles apart. Close to one system, the waves are steep; further from the other system, the waves are much longer and faster--sometimes almost imperceptible except for the "elevator feeling", but still with a significant height. When these waves intersect, their amplitude is additive, possibly creating a wave that's too tall for its wavelength and speed--thus a breaking wall of water. If they're moving in similar directions, that crest will last for a short period--if in very different directions, it will be just momentary (similar to the standing wave), but potentially violent. Then, the waves continue in their respective directions, speeds, and sizes, essentially as if they had never met--perhaps explaining the reported short lives of "rogue waves". This is basic wave mechanics you can illustrate in a large baking pan.

Three weather systems could contribute to an even more extreme result at a point of intersection--the waves are all additive, although the odds of a crest from all three meeting at one point is low enough that it won't happen very often--but it will happen. The rogue will probably be closer to one of the systems, where its waves are shorter-period and steeper. The chances of two or three major weather systems in the same ocean are not exactly one in 10,000 years--at some times of the year they're probably more like one in every few weeks.

The best evidence against my theory is probably that the scientists haven't already come up with it.

Sorry... Somebody else started this.

Edited by - Dave Bristle on 03/10/2009 21:52:12

JohnP
Master Marine Consultant

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1520 Posts

Response Posted - 03/10/2009 : 21:12:44

Hey, Dave, I agree with you that this is a likely explanation that the brilliant, professional scientists have not taken the trouble to refute, at least in that video.

The "linear theory" of a one wave system was proven irrelevant in the videos Steve introduced, but why not the linear theory of a several wave system, as you suggest? It seems surprising to me that other obvious phenomena like that were not discussed.

I've seen rogue mini-waves in the Narragansett Bay and also in the Chesapeake Bay that were much larger than the prevailing waves, and they were always caused by the addition of a large cargo ship's bow wakes to a series of wind waves. These waves were maybe 6 feet high among a constant series of 3 foot waves.

So, how could these eminent theoreticians ignore the Bristle Rogue-Wave Theory? How professional can they be? Don't they read this forum? I bet they are too busy badmouthing each other on the website called Rogue-Wave Anarchy.

Edited by - on

delliottg
Former Mainsheet C250 Tech Editor

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USA
4479 Posts

Response Posted - 03/10/2009 : 21:38:46

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Applications range from space exploration to telecommunications here on earth. Imagine watching and controlling a Mars rover in real time rather than the the current 10 minutes a signal takes to travel the distance between Earth and Mars. Line of sight doesn't seem to matter either! Now that is the future of our Marine Radios! :-)<hr height="1" noshade id="quote"></blockquote id="quote">

As soon as I read this I thought of Heinlein's [url="http://en.wikipedia.org/wiki/Waldo_(short_story)"]Waldo Farthingwaite-Jones[/url].

Edited by - on

Nautiduck
Master Marine Consultant

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USA
3704 Posts

Response Posted - 03/10/2009 : 23:46:05

We encountered a rogue wave a couple of years ago on our lake. It was blowing pretty hard. Most of the waves were about 1' and then suddenly this 3' giant raised up and I thought we were goners. Fortunately the boat dealt with the heavy blow and the only damage was that I dropped my Margarita.

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