Public Education

3 Myths about Rip Currents

BRCH-MAny time you enter the ocean, you enter a dynamic, complex realm, beyond your control and full of surprises. During Rip Current Awareness Week, Sea Grant and our partners focus on educating people about rip currents – one of many physical processes along the coast – because of their potential danger to human life. The United States Lifesaving Association estimates that 80 percent of all rescues at surf beaches are caused by rip currents.

California Sea Grant hopes that by setting the record straight on rip currents – what they are and what they are not – you will be more comfortable in the ocean, less likely to panic when the ocean throws a punch, and more aware of your own limits as an ocean-going swimmer. It’s also plain ole’ good fun to learn about our favorite backyard playground – the beach.

A rip current at Half Moon Bay, extending about 800 feet from shore. Google Earth

A rip current at Half Moon Bay, extending about 800 feet from shore. Google Earth

Myth 1: Rip currents pull you under water.

Fact: Rip currents carry people away from the shore. They are surface currents. They are not “undertows.”

An undertow is a short-lived, sub-surface surge of water associated with wave action. It can drag you down, but it’s not truly treacherous because you won’t be held under for long. Just relax and hold your breath, and you’ll pop to the surface, often on the back side of the waves breaking near shore.

A powerful longshore current sheds eddies into the offshore, creating mega rip currents. Credit: BeachSafe, Australia

A powerful longshore current sheds eddies into the offshore, creating mega rip currents in Orange County. Credit: Tom Cozad

Myth 2: If you get caught in a powerful rip, you can be swept out to sea forever.

Fact: Even under the worst conditions, you won’t be swept to the middle of the ocean, though it could be a long swim back to shore.

Most rip currents are part of a closed circuit, says Robert Anthony Dalrymple, a coastal engineer and rip current scientist at Johns Hopkins University. If you ride a rip current long enough – float along with it – you will usually be taken back to shore by a diffuse, weaker return flow.

The exception to this occurs during fierce storms, when pounding surf sets up powerful longshore currents that shed turbulent eddies. The seaward-flowing arms of these swirling currents may look and feel like “rips,” but they are not part of a circulation cell that will slowly carry you toward shore. Instead you’ll be deposited outside of the surf-zone, sometimes a distance of multiple widths of it. When the surf is big, most people should stay out of the water.

Flash rip currents. Credit: Delaware Sea Grant

Flash rip currents. Credit: Delaware Sea Grant

Myth 3: If you don’t see a rip current, you don’t have to worry about one.

Fact: Rip currents can form spontaneously, in response to the interaction of a lot of waves coming together from many directions at once.

These wave-induced “flash” rips may last only a few minutes or they may pulse – wax and wane – over a longer period of time, says Bob Guza, a coastal oceanography professor at Scripps Institution of Oceanography, UC San Diego, who has studied transient rip current formation in North Carolina and has had California Sea Grant support to study surf-zone dynamics, including rip currents. Flash rip currents are not as powerful or dangerous as other rips but they can nonetheless take people off guard and induce panic.

Read more about breaking the grip of the rip.

Written by Christina S. Johnson, csjohnson@ucsd.edu

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NOAA’s California Sea Grant College Program is a statewide, multi-university program of marine research, extension services, and education activities administered by Scripps Institution of Oceanography at the University of California, San Diego. It is one of 33 Sea Grant programs and is part of the National Oceanic and Atmospheric Administration (NOAA), U.S. Department of Commerce. Visit our website (www.csgc.ucsd.edu) to sign up for email news or follow us on Facebook or Twitter.

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3 thoughts on “3 Myths about Rip Currents

  1. Pingback: Why Are Atlantic Puffins in Danger? | Marine Science Today

  2. Pingback: Watch: rip current in wave tank | Our Ocean

  3. Pingback: Dangerous 2-3 foot surf | Our Ocean

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