NEED TO KNOW
MYTHBUSTING:
RIP CURRENTS
Find out what’s really going on when a rip hits
Words: Tim Scott and Sarah Thompson | Photos: Plymouth University, RNLI/(Nigel Millard, Nathan Williams)
In March this year, St Agnes Lifeguard
Jos Lawrence was patrolling the
beach at Chapel Porth when he
noticed a surfer being swept
suddenly out to sea. ‘As soon as
the guy’s feet left the ground he was
very quickly out of sight,’ he recalls.
Jos knew immediately that the surfer
had been caught out by a rip current.
Jos grabbed a rescue board and
headed out to help the surfer,
guiding him out of the current until
it had eased off and the pair were
able to safely head back to shore.
‘He was okay but in a state of shock
about how quickly everything
had happened.’
ORIGIN OF A MYTH
Rip rescues always attract media
attention because so many people
can get caught out at once. But
they are often incorrectly explained,
with theories of ‘flash rip’ currents
appearing out of nowhere, and the
infamous ‘collapsing sandbar’.
But as Dr Rob Brander, explains in
Dr Rip’s Essential Beach Book:
‘Sandbars just do not collapse.’
He believes the myth is rooted
in a famous rescue at Bondi Beach
in 1938. With around 30,000 people
on the beach, many were bathing
on the shallow sandbars when three
large waves broke on the shore.
Suddenly hundreds of bathers were
dragged into a deep channel and out
to sea. To many, it felt like the ground
gave way beneath their feet. Sixty
surf lifesavers helped almost 300
bathers, of which 35 were rescued
unconscious and revived, while sadly
5 drowned – all in under 30 minutes.
‘HE WAS IN A STATE OF SHOCK
ABOUT HOW QUICKLY
EVERYTHING HAD HAPPENED.’
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NEED TO KNOW
‘It is still often reported as being
caused by a collapsing sandbar,’
explains Rob, ‘but there is a much
more likely explanation: pulsing rip
currents.’ Pulsing rip currents, often
caused by the pumping of a rip
current by a larger group of waves,
can raise water levels in the surf
and increase rip speed.
300 BATHERS
WERE CAUGHT OUT
AT BONDI IN
30 MINUTES
SWIM BETWEEN THE FLAGS
Rip current rescues are the most
common environmental cause of
incidents recorded by RNLI lifeguards,
with over 1,000 people being rescued
from rips every year. Rescues often
happen on the busiest surf beaches
on the exposed south-west coast of
England and Wales, usually on days
when all the elements come together:
a volatile mix of strong rip currents
and sunny weather with lots of people.
Many beach goers are unaware of the
dangers of rip currents.
By understanding how rip currents work,
lifeguards prevent people from getting
into trouble in the first place. Lifeguard
Manager Dickon Berriman explains:
‘Prevention is 95% of what we do, so
awareness is key. Rips can be in different
places each day, so we monitor the
sandbars constantly to ensure people
are safe.’
‘Always swim between the flags’ is a key
RNLI safety message, as lifeguards place
the red and yellow flags in the safest
place on the beach, away from any rip
currents. On busy days there might also
be a lifeguard in the water, providing a
physical barrier between bathers and the
danger area, and lifeguards sometimes
use a PA system to talk to people in the
water. Lifeguards are keen to understand
more about the rip currents, to help
save more lives at sea.
WHAT IS A
RIP CURRENT?
Rip currents are seawarddirected flows or ‘rips’ of water,
driven by breaking waves.
They originate close to the
shoreline and extend out to sea.
They are sometimes referred
to as ‘rip tides’, but they have
nothing to do with the tide.
Rips can travel at up to
4.5mph – almost as fast as an
Olympic swimmer. They are
most commonly found on surf
beaches that have sandbars with
deeper channels between them.
The channels cause variations in
water depth, and therefore the
wave breaking, along the beach.
Rip currents pose such a threat
because they can:
• move someone from a
position of relative safety
to a position of danger in
a very short time
• sweep people into deeper
water further from the shore,
making them feel like the
ground’s disappearing from
under them
• drag people to a region
of heavy breaking waves,
or towards rocks or
coastal structures.
NEED TO KNOW
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INNOVATION THAT LIVES ON
The RNLI teamed up with Plymouth
University for an innovative project to
improve beach safety. From 2010–13,
the researchers at the university’s School
of Marine Science and Engineering
conducted extensive field experiments
to measure the speed and direction of rip
currents. The project was funded by the
Natural Environment Research Council.
The research team, some of whom
are former lifeguards themselves,
then compared the results of these
experiments to RNLI incident data to
identify the conditions when bathers
are most at risk. They turned complex
science into findings that the RNLI can
apply to running our lifeguard service.
Already the results of the study have
been used to develop a pilot rip forecast
system for our lifeguards, in partnership
with the Met Office. It provides
information about rip hazards up to
5 days in advance on 38 of the RNLI’s
lifeguarded beaches. The forecast helps
the RNLI plan lifeguard staffing levels
and manage the safe bathing area.
The public can swim between the flags
in the knowledge that it’s the safest
place to be.
FIND
OUT MORE
Find out more about our
work with Plymouth University here: ripcurrents.co.uk
Have you been caught in a rip? Tell us how you
escaped: @BethanyRHope [email protected]
‘PEOPLE MAKE THE
MISTAKE OF ENTERING
THE WATER WHERE
IT LOOKS CALM’
CIRCULATION: Rips are part of a
circulation pattern. Waves in the surf
zone travel towards the shore, then
break on shallow sandbars, pushing
water towards the shore. Rips return
that water back to the sea.
NECKS AND FEEDERS: Rip feeders
run from the breaking waves towards
the rip channels. In the gap between
sandbars, the feeder turns away from
the shore and water flows out to sea.
Dark streaks caused
by a lack of waves
breaking in the deeper
channels. Rip currents
flow in these channels
A rippled patch
of sea, when the
water around is
generally calm
Other indicators include:
Foam on
the water’s
surface
Debris
floating out
to sea
Discoloured, brown
water caused by
stirring sands
MASS RIP RESCUES: WHY THEY HAPPEN
GOOD WEATHER: When more
people are enjoying the beach, more
people are likely to be caught out.
MODERATE OF BENIGN SWELL
CONDITIONS: Many mass rescues
happen when wave height is below
1m – conditions that seem family
friendly – but when rips are still
relatively strong.
CHANGING CONDITIONS: A rapid
change in conditions (in seconds or
hours), particularly when things have
been calm for a while, can catch
large numbers of bathers off guard
at the same time.
1,000
PEOPLE ARE RESCUED
FROM RIP CURRENTS
EVERY YEAR
NEED TO KNOW
HOW TO SPOT A
RIP CURRENT
BREAKTHROUGH AND
CIRCULATION: Rips ease off when
the currents ‘break through’ the
sandbars and the line of breaking
waves, spreading out and weakening
until the flow disappears. Or the rip
flow turns back towards the breaking
waves and joins the onshore flow.
MORE THAN
6
NEED TO KNOW
RIP CURRENTS DECONSTRUCTED
GETTING OUT
OF TROUBLE
Swimming between the red and yellow flags
is the best way to stay safe. However, if you
are caught in a rip or strong current, always
obey the three Rs:
•Relax: Stay calm and float.
Do not swim against the current,
swim parallel to the shore to escape it.
•Raise an arm to signal for help.
If possible, shout to shore.
•Rescue: Float and wait for assistance.
Don’t panic. Obey lifeguard directions.
If you think you are able to swim in, swim
parallel to the beach towards the breaking
waves. When you’re out of the effects of the
rip, make your way to shore. If you can wade
rather than swim, do so.
RIP CURRENT
NEED TO KNOW
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