Out of nowhere, rise waves with enough strength to smash a ship

April 24, 2005|By Larry Williams | Larry Williams,PERSPECTIVE EDITOR

The way the captain of the Norwegian Dawn tells the story, the sea was calming after a storm when a 70-foot wave seemed to come out of nowhere and hammer the ship carrying 2,200 passengers on a Bahamas cruise this month.

The wave swept over the 10th deck, smashing windows, flooding 62 cabins and injuring four people.

Like others before him, the captain was bewildered by the watery hammer that struck his ship.

In fact, rogue waves, rising high out of the sea to surprise captains and smash ships, have been part of maritime lore for as long as ships have sailed. But until recently scientists treated many of these stories as tall tales.

But recently scientists have begun stripping away some of the mystery. They are discovering that rogues are a surprisingly common menace - one that forecasters may soon be able to offer help in avoiding.

Last summer, the European Space Agency conducted the first satellite survey of the oceans looking specifically for rogues. In three weeks, the satellites discovered 10 rogues, including some taller than 85 feet.

The scientists involved were reported to have been stunned by the results.

Around the world an estimated one or two ships are lost or damaged at sea every week, including a number of big vessels every year. If rogues are responsible for a significant number of these losses, as is now suspected, the implications for sea safety are significant.

"Severe weather has sunk more than 200 supertankers and container ships exceeding 200 meters in length during the last two decades. Rogue waves are believed to be the major cause in many such cases," says a recent report from the space agency.

With increasing international trade, a growing cruise ship industry and steady expansion of offshore oil exploration, finding ways to anticipate or avoid rogue waves is an important challenge.

Recent evidence of the dangers is plentiful.

In March 2001 in the South Atlantic, a sheer wall of water almost 100 feet tall smashed into the cruise ship Caledonian Star, smashing windows and flooding the command deck.

Weeks earlier, another cruise ship in the same waters, the Bremen, suffered a similar fate. The Bremen was left drifting without navigation or propulsion for two hours.

In 1995, the liner Queen Elizabeth 2 was slapped by a rogue wavein the North Atlantic that Capt. Ronald Warwick said "looked as if we were going into the White Cliffs of Dover," according to the space agency report.

The colliding weather systems that created what has come to be called the Perfect Storm off the coast of New England are believed to have bred a number of rogue waves that sealed the fate of the fishing trawler Andrea Gail and her crew.

Teams of European scientists have been working together in a just-concluded three-year project called "Max Wave" to study the danger. American scientists, including Mark A. Donelan and researchers at the University of Miami's Rosenstiel School of Marine and Atmospheric Science have joined the effort.

Using satellite data from the southeastern United States and northern South America, Donelan and his colleagues hope to develop a system that uses information on the movement of weather systems and ocean currents, and sea depth to offer timely warnings of where rogue waves might occur.

Ships generally try to sail into waves when seas are rough. But Donelan says rogue waves can be particularly devastating because they usually arise from a direction other than the prevailing wave action, smashing the ship on its side.

He says rogue waves are most common and dangerous where there are strong currents like the Gulf Stream off the east coast of the United States, where there is heavy cruise and container ship traffic, and the Agulhas current off the east coast of Africa, where there is a large volume of Mideast supertanker traffic.

Donelan thinks the combination of the currents and two colliding storm systems sometimes focuses waves moving toward each other at an angle to briefly create a rogue wave.

Owen M. Phillips, professor emeritus in the Department of Earth and Planetary Sciences at the Johns Hopkins University agrees. He likens the process to the way a lens focuses light.

Donelan says shallow water can multiply the power of rogue waves by causing them to break with extraordinary power over unprotected ships.

Oil drilling platforms in the North Sea and off the coast of Norway have also been severely damaged when tall rogues have smashed over their lower decks.

Radar data from the North Sea's Goma oil field recorded 466 rogue wave encounters in 12 years, helping to convert previously skeptical scientists, the Eurpean Space Agency said. It noted that statistics showed such large deviations from the surrounding sea state should occur once every 10,000 years.

Donelan hopes warnings could be issued when storm systems are colliding, particularly in areas where there are strong currents and shallow waters.

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