Rogue Giants at Sea, Scientists Find Swells 'More Frequent Than We Expected'
The storm was nothing special. Its waves rocked the Norwegian Dawn just enough so that bartenders on the cruise ship turned to the usual palliative — free drinks.Monster Waves Rogue Giants at Sea

Then, off the coast of Georgia, early on Saturday, April 16, 2005, a giant, seven-story wave appeared out of nowhere. It crashed into the bow, sent deck chairs flying, smashed windows, raced as high as the 10th deck, flooded 62 cabins, injured 4 passengers and sowed widespread fear and panic.

“The ship was like a cork in a bathtub,” recalled Celestine Mcelhatton, a passenger who, along with 2,000 others, eventually made it back to Pier 88 on the Hudson River in Manhattan. Some vowed never to sail again.

Enormous waves that sweep the ocean are traditionally called rogue waves, implying that they have a kind of freakish rarity. Over the decades, skeptical oceanographers have doubted their existence and tended to lump them together with sightings of mermaids and sea monsters.

But scientists are now finding that these giants of the sea are far more common and destructive than once imagined, prompting a rush of new studies and research projects. The goals are to better tally them, understand why they form, explore the possibility of forecasts, and learn how to better protect ships, oil platforms and people.

The stakes are high. In the past two decades, freak waves are suspected of sinking dozens of big ships and taking hundreds of lives. The upshot is that the scientists feel a sense of urgency about the work and growing awe at their subjects.

“I never met, and hope I never will meet, such a monster,” said Wolfgang Rosenthal, a German scientist who helped the European Space Agency pioneer the study of rogue waves by radar satellite. “They are more frequent than we expected.”

Drawing on recent tallies and making tentative extrapolations, Dr. Rosenthal estimated that at any given moment 10 of the giants are churning through the world’s oceans.

In size and reach these waves are quite different from earthquake-induced tsunamis, which form low, almost invisible mounds at sea before gaining height while crashing ashore. Rogue waves seldom, if ever, prowl close to land.

“We know these big waves cannot get into shallow water,” said David W. Wang of the Naval Research Laboratory, the science arm of the Navy and Marine Corps. “That’s a physical limitation.”

By one definition, the titans of the sea rise to heights of at least 25 meters, or 82 feet, about the size of an eight-story building. Scientists have calculated their theoretical maximum at 198 feet — higher than the Statue of Liberty or the Capitol rotunda in Washington. So far, however, they have documented nothing that big. Large rogues seem to average around 100 feet.

Most waves, big and small alike, form when the wind blows across open water. The wind’s force, duration and sweep determine the size of the swells, with big storms building their height. Waves of about 6 feet are common, though ones up to 30 or even 50 feet are considered unexceptional (though terrifying to people in even fairly large boats). As waves gain energy from the wind, they become steeper and the crests can break into whitecaps.

The trough preceding a rogue wave can be quite deep, what nautical lore calls a “hole in the sea.” For anyone on a ship, it is a roller coaster plunge that can be disastrous.

Over the centuries, many accounts have told of monster waves that battered and sank ships. In 1933 in the North Pacific, the Navy oiler Ramapo encountered a huge wave. The crew, calm enough to triangulate from the ship’s superstructure, estimated its height at 112 feet.

In 1966, the Italian cruise ship Michelangelo was steaming toward New York when a giant wave tore a hole in its superstructure, smashed heavy glass 80 feet above the waterline, and killed a crewman and two passengers. In 1978, the München, a German barge carrier, sank in the Atlantic. Surviving bits of twisted wreckage suggested that it surrendered to a wave of great force.

Despite such accounts, many oceanographers were skeptical. The human imagination tended to embellish,