Friday, July 1, 2016

Everything You Know About Surviving Rip Currents Is Wrong (Maybe)

Conventional wisdom says that Jamie MacMahan was doing everything right when, about a decade ago, he found himself caught in a rip current while swimming off the coast of Monterey, California. Rips flow seaward, out to deep water, so beach access signs across the country advise swimmers to paddle parallel to the beach to escape them. The savage, dread-inducing flows kill more beachgoers each year than any other threat and MacMahan, a professor of oceanography and a strong swimmer, was following the “swim parallel” gospel, paddling steadily. But as he thrashed in the cold Pacific, the rip refused to relent. “I thought, ‘That’s interesting,’” MacMahan says.

MacMahan, it’s important to note, had done this to himself. A rip current expert at the Naval Postgraduate School in Monterey, he had volunteered to subject himself to the rip for a safety video the National Oceanic and Atmospheric Organization was filming. With plenty of experience, he wasn’t in serious danger. “But as I was swimming parallel to the shore, left and right, I noticed that it was easier to swim one direction more than the other,” MacMahan says. The safety guidelines he was promoting—the life-saving advice we tell the millions of Americans who flock to the beach each summer—he thought, could be wrong.

In the last five years, MacMahan’s research has upended the field of rip current studies. Since that initial experience in Monterey, he’s used GPS devices to meticulously track nearshore currents in the U.S., England, and France, and has jumped into rips around the world. Rips can form on any beach, MacMahan says, and swimmers usually don’t know a rip’s present until they’re in its clutches. Panicked victims often try to swim directly back to shore—against the powerful offshore flow. Swimmers familiar with rips might try swimming parallel to escape. But MacMahan’s research suggests doing the unthinkable: giving in and going with the flow.

Eighty to 90 percent of rips MacMahan has studied flow in huge circles, from the shallows, out through the breakers and back again, every few minutes. A swimmer stuck in a circulating rip has no way of knowing which way the current is flowing. That means that by swimming parallel to the shore—something signs at nearly every popular beach in the country advise—the swimmer has a 50/50 chance of paddling against the deadly current.

“If you can relax—and it’s a long time, for maybe three minutes—you’re generally going to float back to the beach,” MacMahan says.

It’s a radically simple finding—one that challenges our primordial instincts and everything we think we know about beach safety. The discovery, which MacMahan published in Marine Geology in 2010 and calls rip current “circulation,” is still contentious six years later. His peer-reviewed findings have dramatically changed the way Australia tells its citizens how to survive this menace. But at home, MacMahan’s work is considerably more controversial and his research has opened a gaping divide in the sleepy rip current field.

“The reaction to Jamie’s findings has polarized the community,” says Rob Brander, a prominent rip researcher. For some leaders in the field, MacMahan’s recommendation to simply float through a rip current is, at best, an idea to be ignored and dismissed; at worst, though, the advice is potentially deadly.

by David Ferry, Outside |  Read more:
Image: Todd Quackenbush/Unsplash