What is a Rogue Wave and why they are so dangerous

Reported by the sailors at least since the 19th century, a rogue wave is a very large, extremely steep, unexpected and suddenly appearing surface wave. It is also called as a freak wave, monster wave, killer wave, and extreme wave.

For centuries, seamen told stories about encounters with extremely big, ship-sinking waves, much bigger than any wave surrounding them. According to sailors, these waves were also so steep – almost vertical, insurmountable walls of water.

Rogue wave (Bay of Biscay)
A merchant ship laboring in heavy seas as a huge wave looms ahead, ca. 1940. Huge waves are common near the 100-feet line in the Bay of Biscay. Picture taken in the Bay of Biscay near the 100-fathom curve, off France, ca. 1940. Published in Fall 1993 issue of Mariner’s Weather Log. Image source: Wikipedia

Until 1995 (see the Draupner wave section below), scientists often dismissed these stories as absurd. But it’s normal given the rarity of credible eyewitnesses, as people who encountered these huge waves usually were not coming back to tell their tale. Furthermore, sailors like made-up stories and exaggerating things. So, rogue waves considered sailors’ yarn, just like giant sea-monsters (i.e. Kraken) or mermaids.

Not only sailors, even scientists who witnessed a rogue wave were ridiculed: for example, In 1826, French scientist, explorer and naval officer Captain Jules Dumont d’Urville (23 May 1790 – 8 May 1842) reported waves as high as 108 feet (33 meters) in the Indian Ocean with three colleagues as witnesses. He was publicly ridiculed by fellow scientist François Arago (26 February 1786 – 2 October 1853), the French mathematician, physicist, astronomer, freemason and politician.

In the early 19th century, it was widely held that no wave could exceed 30 feet (9 meters).

Then, for almost 100 years, scientists and ship designers have used a mathematical system commonly called the Gaussian function (or Gaussian Sea or standard linear model) to predict wave height. According to this model, in a big storm sea with a significant wave height of 12 meters (39 feet), there will hardly ever be a wave higher than 15 meters (49 feet).

If the average wave height is 12 meters (39 feet), the model predicts 30-meters (98-feet) waves can occur only once in ten thousand years.

The mysterious sinking of MS München

On December 12/13 night, 1984, the Greek Panamax freighter Marion received a distress call in the form of SOS code from a huge German carrier named MS München, which was sailing in the North Atlantic. Marion relayed the message to the Soviet freighter Marya Yermolova and the German tug boat Titan. Automatic emergency signals were also received by multiple radio stations starting at 04:43.

No further calls were recorded after 07:34.

There was a fierce storm had been raging since November in the area. But the München had been designed to cope with such conditions. It was 261.4 meters long (858 feet) with a draught of 11 meters (36 feet). Only six-year-old at the time, the ship was one of the newest and most modern carriers of its time. It was even considered as “unsinkable”.

MS München
MS München was one of the newest and most modern carriers of its time. It was even considered as “unsinkable”. Image source: seefunknetz.de

The initial search requested by HMCG was by RAF Nimrod maritime reconnaissance aircraft, coordinated by SRCC RAF Mountbatten. They found nothing. The ship was lost without a trace as if it had never existed.

What followed was the biggest search and rescue operation ever conducted in the North Atlantic. For one week over, 13 aircraft from the United States, the United Kingdom, Portugal, and West Germany, and nearly 80 merchant and naval ships had searched for the München or her crew through an area the size of Mexico.

Despite the intense search operation, only a few life jackets, a single container, and four empty life rafts could be recovered. With these few remains, it was impossible to determine the cause of the sinking.

A week after it had begun, on the evening of December 20, the international search operation officially ended. The West German government and Hapag-Lloyd, the company who owns MS München, decided to search for two more days, with British and American forces supporting them.

Two months later, on February 16, the car transporter Don Carlos salvaged a floating lifeboat from the starboard side of MS München, the last object discovered from her. And this lifeboat provided some clues: the pins, which should have hung vertically, had been bent back from forward to aft, indicating the lifeboat hanging below it had been struck by a huge force, that had run from fore to aft of the ship, and had torn the lifeboat from its pins.

The recovered lifeboat normally hung 20 meters (65 feet) above the waterline. A wave with enough power to do that damage would have needed significantly higher than 20 meters. With the existence of rogue waves then considered so statistically unlikely as to be near impossible (as explained above), the investigation finally concluded that the severe weather had somehow created an “unusual event” that had led to the sinking of the München.

MS München was neither the first ship suddenly disappeared in the middle of the ocean, nor the last one. All these incidents blamed on technical defects, human errors, or design fault.

Until the 1st day of 1995.

Draupner wave: the first rogue wave to be detected

There’s a complex called “Draupner platform” located 160 km (99 mi) offshore from Norway, which is responsible for monitoring pressure, volume and quality of gas flows in Norway’s offshore gas pipelines. The complex consists of seven risers and two riser platforms standing in 70 meters (230 feet) water depth and linked by a bridge.

To ensure the safety of the people on board, the platform is equipped with an extensive array of sensors and and scanners that track among many other things the frequency and height of the waves below.

On January 1, 1995, when significant wave height of approximately 12 meters (39 feet), one of these sensors detected a freak wave with a maximum wave height of 25.6 meters (84 feet) occurred. Its peak elevation above still water level was 18.5 meters (61 feet).

It was more than twice the height of any other wave recorded in hours before and after, and also six meters (20 feet) higher than the hypothetical ocean wave scientists at that time believed would occur only once in 10,000 years.

Furthermore, that huge wave hit the rig at 72 km/h (45 mph)!

Prior to that measurement, no instrument-recorded evidence for rogue waves existed–just anecdotal evidence provided by those who had encountered them at sea.

The reading made by a downwards-pointing laser sensor was also confirmed by a minor damage on the platform.

So, the monster waves in sailors’ tales were real. The Draupner wave or New Year’s wave became the first rogue wave to be detected by a measuring instrument,

Draupner wave record - the first rogue wave to be detected
Draupner wave record. The Draupner wave or New Year’s wave was the first rogue wave to be detected by a measuring instrument.

Queen Elizabeth 2 encounters with a rogue wave

Just a few months later, on September 11, 1995, about 200 miles south of eastern Newfoundland, ocean liner Queen Elizabeth 2 encountered a rogue wave, estimated at 27 meters (89 feet), caused by Hurricane Luis in the North Atlantic Ocean.

The captain of the ship has said that the wave “came out of the darkness” and “looked like the White Cliffs of Dover”.

Rogue waves are really dangerous

Rogue wave
A rogue wave estimated at 18.3 meters (60 feet) in the Gulf Stream off of Charleston, S.C. At the time, surface winds were light at 15 knots. The wave was moving away from the ship after crashing into it moments before this photo was captured. Image source: National Oceanic and Atmospheric Administration (NOAA) website

Rogue waves present considerable danger for several reasons: they are rare, unpredictable, may appear suddenly or without warning, and can impact with tremendous force.

A 12-meter (39 feet) wave in the usual “linear” wave model would have a breaking pressure of 6 metric tons per square meter [t/m2] (8.5 psi). Although modern ships are designed to tolerate a breaking wave of 15 t/m2 (21 psi), a rogue wave can dwarf both of these figures with a breaking pressure of 100 t/m2 (140 psi).

The “three sisters”

Apart from one single rogue wave, the rogue wave may be part of a wave packet consisting of a few rogue waves. Such rogue wave groups have been observed in nature.

A phenomenon which is known as the “Three Sisters” is said to occur in Lake Superior (yes, rogue waves can also occur in lakes) when a series of three large waves forms.

Largest rogue wave ever recorded

At 25.6 meters (84 feet), the Draupner wave still remains the largest rogue wave ever properly measured.

In February 2000, a British oceanographic research vessel, the RRS Discovery, sailing in the Rockall Trough west of Scotland encountered the largest waves ever recorded by scientific instruments in the open ocean, with a significant wave height of 18.5 meters (61 feet) and individual waves up to 29.1 meters (95 feet).

But these waves were not rogue waves. By definition, rogue waves are more precisely defined as waves whose height is more than twice the significant wave height (the mean wave height -trough to crest- of the highest third of the waves).

So, if the significant wave height is only one meter, for example, any wave larger than two meters is a rogue wave.

The biggest wave ever recorded

An earthquake followed by a landslide on July 9, 1958, in Alaska’s Lituya Bay generated a wave 30.5 meters (100 feet) high, the tallest megatsunami and the biggest wave ever documented. When the wave ran ashore, it snapped trees 524 meters (1,714 feet) upslope. Five deaths were recorded, but property damage was minimal because there were few cities or towns nearby.

Rogue Waves – In this episode we will cover the most elusive of all waves and explain where they come from and how dangerous they can be.
With 310 meters of usable length and a width of 5 meters the Large Wave Flume (GWK) in Hanover, Germany is currently the largest wave tank in the world. The wave paddle of the hydraulic wave machine (900 kW) is 7 m tall and includes a ±10 degree rotatable flap. The overall stroke of the wave generator is 4,2 m. By generating small and slow waves followed by faster and bigger waves, rogue waves (or “freak waves”) can be produced. The wave tank is used to simulate the impact on structures or ships.
To simulate the sea conditions even more realistic in the future, the Large Wave Flume will get an additional water current system and a new improved wave generator in the following years.

Sources

M. Özgür Nevres

I am a software developer, an ex-road racing cyclist, and a science enthusiast. Also an animal lover! I write about the planet Earth and science on this website, ourplnt.com. You can check out my social media profiles by clicking on their icons.

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