Download Scott McDowell, Ph.D. The Reality of Rogue Waves

Scott McDowell, Ph.D.
Sea Science Articles written for The Triton magazine
The Reality of Rogue Waves
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 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 five- to eight 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 in order 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. A subset of these tragedies is
given below.
1826 – Indian Ocean. French scientist and naval officer, Capt. Jules d’Urville reported waves as high as
108 ft, yet was publicly ridiculed by the Prime Minister as it was believed no wave could exceed 30 ft.
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-ft wave and listed 52 degrees but slowly righted
herself.
Scott McDowell, Ph.D.
Sea Science Articles written for The Triton magazine
1975 - Lake Superior. The SS Edmund Fitzgerald of musical fame was a 729-ft bulk cargo vessel that sank
suddenly during a gale storm with all 29 crew members aboard. Another ship nearby was hit by two
35-ft waves within ten 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 ft 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 ft.
1995 – North Atlantic. The cruiser liner RMS Queen Elizabeth II encountered a 95-ft 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, both
had bridge windows smashed and all power and instrumentation lost, upon encountering 98-ft rogue
waves.
2005 – North Atlantic, offshore Georgia. The cruise liner Norwegian Dawn encountered 70-ft rogue
waves that damaged windows on the 9th and 10th decks.
During the past two decades, severe weather has sunk more than 200 supertankers and container ships
exceeding 650 ft in length, with rogue waves are 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 ft 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’s article will present forensic analyses of rogue wave impacts on sunken vessels, as well as
new developments in rogue wave predictions and ABS guidelines.
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