By definition, a rogue is one who behaves unexpectedly and abnormally, often causing damage to anything nearby. This succinctly describes the extremely large and unpredictable rogue waves that are gaining notoriety on our world’s oceans.
Rogue, freak or killer waves have been part of marine folklore for centuries but have only recently become accepted as real phenomenon. Large and spontaneous, they occur most frequently in the open ocean but have also caused havoc in the U.S. Great Lakes.
Rogues can occur where major storms generate packets of extreme waves that combine and amplify, but also amidst calm seas with virtually no warning and from directions other than prevailing winds and seas. Occasionally they are formed when a large swell approaches and opposes major current systems such as the Atlantic Gulf Stream and the Agulhas Current off South Africa.
Waves are typically classified as rogues when they are 5-8 times higher than the largest waves of the existing sea state. Recent studies have also proven the existence of rogue wave holes, which are not always accompanied by a large wave crest. These deep wave troughs can be equally disastrous for vessels.
Prior to the 20th century, there was little mention of this dangerous phenomenon, likely because ships that encountered rogue waves would never return to port. Nowadays, ships are designed with more structural integrity than in previous years.
Oceanographers, the Office of Naval Research, the American Bureau of Shipping (ABS) and maritime insurance companies are now working diligently to determine the characteristics, probability and impacts of rogue waves to prevent loss of life and commercial assets. Rogue waves are no more prevalent now than in the past – we’re just getting better at documenting occurrences.
In 2007, NOAA compiled a worldwide catalogue of more than 50 maritime incidents likely associated with rogue waves, many having caused sudden loss of ocean-going vessels. Some of them include:
1826, Indian Ocean. French scientist and naval officer Capt. Jules d’Urville reported waves as high as 108 feet, yet was publicly ridiculed by the prime minister as it was believed no wave could exceed 30 feet.
1942, North Atlantic. While carrying 16,082 U.S. troops during wartime, the British passenger liner RMS Queen Mary was broadsided during a gale by a 92-foot wave and listed 52 degrees but slowly righted herself.
1975, Lake Superior. The SS Edmund Fitzgerald of musical fame was a 729-foot bulk cargo vessel that sank suddenly during a gale storm with all 29 crew members aboard. Another ship nearby was hit by two 35-foot waves within 10 minutes of the Fitzgerald’s breaking in two pieces and immediately sinking to the bottom.
1980, offshore Japan. The MV Derbyshire, a 91,655 GRT bulk freighter, was the largest British vessel ever lost at sea, with 44 aboard. The wreck was located in 1994 and subsequent analyses indicated that waves of at least 92 feet caused the cargo hatches to burst, leading to rapid sinking of the vessel.
Beginning in the mid-1990s, many rogue waves have been observed, some using sophisticated technologies that allow valuable, quantitative analyses and subsequent improvements of numerical forecasting models.
1995, North Sea, midway between Scotland and Norway. The stationary Draupner oil production platform, heavily instrumented with engineering sensors, yielded the first scientific confirmation of rogue waves, with a maximum height of 84 feet.
1995, North Atlantic. The cruise liner RMS Queen Elizabeth II encountered a 95-foot rogue wave during a hurricane in the North Atlantic. The captain described it as “a great wall of water … that came out of the darkness and looked like the White Cliffs of Dover.”
2001, South Atlantic. Two Bahamian-registered cruise ships, MS Bremen and MS Caledonian Star, had bridge windows smashed and all power and instrumentation lost upon encountering 98-foot rogue waves.
2005, North Atlantic, offshore Georgia. The cruise liner Norwegian Dawn encountered 70-foot rogue waves that damaged windows on the ninth and 10th decks.
During the past two decades, severe weather has sunk more than 200 supertankers and container ships exceeding 650 feet in length, with rogue waves believed to be the major cause. Surface radar data are increasing our confidence in these observations: data from the Goma oilfield in the North Sea identified 466 rogue waves in 12 years (nine days between rogues) in just this relatively small area. In 2004, scientists analyzing ocean-surface radar images from European Space Agency satellites observed 10 rogue waves of 82 feet or higher during a three-week period – roughly one every two days, on a global basis.
It has also been suggested that rogue waves are responsible for the loss of several low-flying aircraft, namely U.S. Coast Guard helicopters on search and rescue missions. Maybe downed aircraft in the Bermuda Triangle, too.
Next month, I’ll present forensic analyses of rogue wave impacts on sunken vessels, as well as new developments in rogue wave predictions and ABS guidelines.
Scott E. McDowell has a doctorate in ocean physics, is a licensed captain and author of Marinas: a Complete Guide, available at www.scottemcdowell.com. Comment at firstname.lastname@example.org.