Ship-Sinking Monster Waves Revealed

vinlud writes "Once dismissed as a nautical myth, freakish ocean waves that rise as tall as ten-storey apartment blocks have been accepted as a leading cause of large ship sinkings. Results from ESA's ERS satellites helped establish the widespread existence of these 'rogue' waves and are now being used to study their origins. ESA writes about it in a story. More information about this phenomena at the website of Karsten Trulsen, Associate Professor at the University of Oslo."

New Extreme Sport Prediction

[4of12]

Skiers I know have sometimes gone heli-skiing, getting the copter to drop them onto otherwise hard-to-access mountains with pristine deep powder.

There's probably some surfers that have Been There-Done That ® on Diamond Head in Hawaii that would pay for a chance to be dropped down onto a 25-meter wave.

If the ESA satellite data can be used to find the waves before they disappear, some dudes could be riding some truly radical waves.

You shouldn't be

[Spamalamadingdong]

Chance sightings and measurements of these brief phenomena are one thing, a global census-by-sampling is quite another.

But no beach for spectators

[Engineer-Poet]

First, if those waves were moving that fast, they would not be so tall (tsunamis are only inches high as they cross the oceans). Second, the waves would not be dangerous to ships if they were not steep. Third, you could keep up with almost any wave if you used something like a hydrofoil board.

The real problems are that you have to take a boat or aircraft from wave to wave (IF you can forecast them well enough), there is no beach to camp on between waves and no vantage point for spectators. The high costs and difficulty of milking spectators for money makes it unlikely that a sport would develop.

Re:Why not near coasts?

[jerde]

How come these are never reported near coasts? At the frequency they were detected, you think there would be a tsunami event somewhere every week or so.

My understanding of them is that they aren't a single "wave" traveling along, carrying some large amount of energy. Instead, the appearance of a rogue wave is just a temporary concentration of the local wave energy into one spot.

It's a constructive interference effect, and doesn't last long or travel far. Longer waves move more quickly than shorter waves, so by chance you could get a few different waves that all catch up with each other and produce a temporary HUGE wave in one particular location. The individual waves then drift apart as they move at their different rates.

The whole controversy is the math that goes into predicting how common such a coincidence is. I do not actually understand the math involved, but my guess is there is some effect that makes it easier for the waves to line up with each other to cause the effect. (Sort of like a magnetic attraction -- as the waves pass each other, something helps the phases line up more than a simple linear combination would suggest)

There is an EXCELLENT animation [math.uio.no](animated GIF, 1.7MB) on the Karsten Trulsen [math.uio.no] site linked to in the story here. It shows how intentionally lined-up waves of different frequencies will all catch up with each other to form a large local wave. It then also shows how that same sequence of waves can be placed in amidst "normal" ocean waves, and the same effect still appears. Very cool to watch.

A tsunami, on the other hand, IS a single, large-energy wave, and is a completely different phenomenon.

- Peter

"Two large ships per week" ?!

[Anonymous Coward]

The article reads:

two large ships sink every week on average

Is that correct ?