Storms bring dangerous energy to surf

September 01, 1995|By Douglas Birch and Dail Willis | Douglas Birch and Dail Willis,Sun Staff Writers

Heavy weather at sea has turned the waning weeks of the summer into a treacherous time along Atlantic beaches.

A swarm of storms has churned up towering waves and fierce riptides along the Eastern seaboard, claiming the lives of unlucky or inexperienced swimmers and keeping lifeguards scrambling.

"Hurricane Felix was the first storm that really started to bring the heavy surf in," said Dr. Stephen P. Leatherman, director of the laboratory for coastal research at the University of Maryland College Park. Felix was born Aug. 10.

"Now you've got a bunch more of these things out there, and they're still energizing the Atlantic Ocean," he said.

On Wednesday night, a 10-year-old boy, Thomas Kennedy of Boston, was swept out of his father's arms and carried out to sea near 136th Street in Ocean City. He is presumed drowned. He was the fourth drowning victim in Ocean City this summer and, by one unofficial count, at least the 13th along the Atlantic Coast.

But deaths don't tell the whole story.

In one frantic week, beginning Aug. 13, Ocean City's lifeguards plunged in the water 1,559 times to aid swimmers -- more than the entire 1994 total of 1,484 rescues, said Capt. George Schoepf of the city's Beach Patrol.

As of Sunday, the Beach Patrol had gone after swimmers in trouble 4,520 times, about three times last summer's total.

"It's been a very interesting summer," said Captain Schoepf. "The extreme heat, the hurricanes, the nor'easters, the mass amount of people on the beach."

Bill Ryan, director of the rescue service for Nags Head, N.C., said his lifeguards have rescued about 150 people this summer, double last year's total.

One person drowned on the 20 miles of shoreline covered by Mr. Ryan's lifeguards. Those Outer Banks beaches, though, are far less crowded than Ocean City's.

"We've had a lot of heavy surf, a lot of rip currents and a lot of debris in the water," he said.

Coast Guard officials haven't compiled this summer's statistics for the Atlantic Coast yet. But a spokesman said that, in the Middle Atlantic region, there has been an increase in the number of search-and-rescue operations for swimmers.

A dozen tropical storms or hurricanes have already steamed across the Atlantic, with the peak of the season due in about two weeks. This season has already passed the 1936 record of nine named storms by Aug. 23. And it's on a pace to match 1933's record for the most storms of any season.

Yesterday, Hurricanes Humberto, Iris and Luis along with Tropical Storm Karen, were all churning away, stacked up like planes over a crowded airport.

At sea, a good-sized storm can generate 30-foot waves, Dr. Leatherman said. They don't reach shore, because the size of a wave is limited to about four-fifths of the depth of the water it travels through.

But a storm's energy still pumps up the size of coastal surf.

In a typical summer, waves at Ocean City and other Atlantic resorts are generally two to four feet high. Under the influence of the hurricane conga line offshore, they've swollen to four to six feet, Dr. Leatherman said.

Exponential power

The difference between a three-foot wave and a six-foot wave may not seem impressive, especially to the casual swimmer. But Dr. Leatherman, who is writing a book about beach safety, pointed out that the power of a wave grows with the square of its size.

That means that a three-foot wave is nine times more powerful than a one-foot wave. And a five-foot wave is 25 times more powerful than a one-foot wave.

Swimmers caught in heavy surf can get knocked around, pummeled and swept back into the next set of waves by the receding "swash" -- the water from a spent wave -- rushing back from the beach.

Sometimes, big waves come in the form of "shorebreak" waves, which, as their name implies, roll in undisturbed over offshore sandbars and crash directly into the sandy shore. These "can drive you straight into the beach," Dr. Leatherman said. "That's what breaks people's necks."

Shorebreak waves generally occur where the beach slopes steeply into the water. And steep beaches are typically made of coarse sand -- like the sand poured onto Ocean City's beaches during beach replenishment.

But the biggest danger to ocean swimmers generally are riptides.

Strong riptides are generated by heavy surf that piles up water on the beach. The water has nowhere to go, of course, except back out into the ocean. And so it flows along the sand until it finds a seaward current, which generally occurs where there is a break in the offshore sandbar.

The bigger the waves, the more water piles up near shore. The more water that piles up, the stronger the seaward rip current.

"These things can pull you offshore at three, or four or five feet per second," Dr. Leatherman said.

That's about 4 miles an hour, or about the pace of a casual jogger.

Swimmers' big mistake

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