The Great Bondi Rip Experiment

By Dan Hutton on October 27, 2010 in

Summer’s almost here and Christmas is just around the corner so I’m very tempted to devote this entire article to plugging my new book, ‘Dr Rip’s Essential Beach Book; everything you wanted to know about surf, sand and rips’, which should be required reading for anyone who goes to the beach (and makes a terrific stocking stuffer to boot!). But that would be indulging in shameless self-promotion, so I’ll talk about the rip current experiment I did at Bondi in early September instead.

Last summer saw a huge debate in the media about whether you should ‘swim parallel’ or ‘stay afloat’ if you get caught in a rip. For many years, the traditional wisdom was that rips flow way out to sea, so getting out of them by swimming to the side before this happens makes good sense… if you can swim. Surf Life Saving Australia launched a national rip education campaign based on the message, “To escape a rip, swim parallel to the beach”. They were accused by a lot of people of choosing a ‘dangerous’ message. The ‘stay afloat’ advocates reckoned that staying calm and signaling for help was a better way to go. This was backed up by scientific experiments in the US, UK and France that showed rips flow in circles without going beyond the breaking waves about 80% of the time. So if you stay afloat, the odds are in your favour that you’ll naturally get swept back onto the safety of shallow sandbars (eventually).

Sounds good, but what about the 20% of the time that the rips spit you out the back? Who’s going to save you then, especially on unpatrolled beaches where almost all drownings occur?

The debate continued to rage on, so the SLSA helped us do our own experiment at Bondi. We chucked a bunch of drifters that looked like mini rockets into a rip in the middle of the beach. The drifters floated through the surf like a swimmer would and had GPS units attached to tell us how fast and far they went and where they ended up. We also had teams of swimmers (with GPS units strapped on) enter the rip to test the ‘stay afloat’ and ‘swim parallel’ options. As it turns out, about 90% of the time the drifters went in circles. All the swimmers who swam parallel made it out of the rip onto the sandbar and all the people ‘staying afloat’ ended up on the sandbar too.

So what did we learn? We learned that the rip behaved like most other rips – good swimmers can swim parallel to get out but staying afloat works too. And so the debate goes on.

While it’s good to have both messages out there, I strongly suspect that the average person who gets caught in a rip panics and all the advice goes out the window as they freak out. It’s much better not to get in a rip in the first place, which means you should learn how to spot a rip.

Conveniently, there just happens to be a chapter in my book devoted to that, and you can order a discounted copy at www.scienceofthesurf.com!

‘Dr Rip’s Essential Beach Book; everything you wanted to know about surf, sand and rips’ is available in all good book stores.