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Small waves? Big trouble!   by Daren Jenne

Enjoying our waters, and when not to go out

August 2019

'The waves don’t look that big.' 'I will only go out up to my knees.' 'I’m a strong swimmer. I’ll be fine.' As a veteran ocean lifeguard, I have heard the above statements time and time again from beach-goers wanting to swim in dangerous conditions.

Now that Phuket’s waves have temporarily become smaller, it is tempting to take a jump into the warm waters of the Andaman Sea. Is it safe to do so?

That depends on your swimming ability and experience with the ocean. Read on to learn more.

Long or short period – what’s the difference?

Over the last two weeks, two-to-three metre waves have pounded Phuket’s west coast beaches. As big as that sounds, the real danger lies not only in the size of the waves, but their frequency, or how often they break.

‘Long period’ swells hit Phuket’s west coast shores only occasionally. This type of wave is created by far-away storms and the winds they spin up over the distant ocean. The waves created by these winds arrive at Phuket’s beaches 14 or more seconds apart. As they approach the shore and ‘feel’ the shallower water, the top of the wave eventually overtakes the bottom, and the wave breaks. For surfers, these are dream waves. For swimmers, these waves can be powerful, and should be approached with caution.

However, the longer period in-between waves provides time to take a few breaths, and get ready to dive under the next wave. These waves also come in groups, with long, calm lulls in between. While these lulls can provide tired swimmers time to recover before the next group of waves arrive, they can also be deceptive.

Inexperienced ocean swimmers may only watch the ocean for a minute or so, before deciding the waves look very small, and then enter the water. In reality, they have observed the ocean during a lull when no long-period waves are arriving. Then, once they are out in the water, another group of large ‘set’ waves arrives, which can overwhelm them.

Wind swell

Unfortunately, Phuket’s prevailing and dominant source of waves are ‘short period’ wind swell. These waves are whipped up by the local winds of the SW monsoon. They blow towards the northeast right across Phuket’s beaches. The result? These waves are spaced only six to eight seconds apart. When local wind waves reach over two metres, they are extremely dangerous, because swimmers in distress have very little time to surface and breathe before the next wave hits them.

Plus, short period wind waves have few lulls in-between sets of larger waves. Once tired, inexperienced ocean swimmers, and even strong pool swimmers can become quickly overwhelmed by the frequency of the turbulent whitewater waves. Plus, there is almost always a background long period swell ‘hiding’ in the near constant short-period wave train. When these hidden long period waves combine with the already strong wind swell, the power of the surf becomes very intense, and wave heights increase suddenly and unpredictably.

Flash rip currents

This combination of waves also creates Phuket’s infamous flash rip currents. These pulsing, outward-going currents can reach incredible strength and speed. They can form suddenly in one area of the beach, where anyone in the water above their knees could suddenly be in danger. As soon as these waves begin to break, the water can suddenly rise. Those who were previously wading suddenly find the water over their waist and pulling strongly outward. Then, these currents suddenly dissipate, only to reappear in a few minutes in another area of the beach. Even the fastest and strongest swimmers can not make forward progress swimming against these currents. Unaccompanied children are especially vulnerable to this type of sudden, outgoing current.

Anyone entering the sea on Phuket’s west coast beaches, where consistent, breaking waves are present, should only do so in swimming areas marked by red-and-yellow flags. If these flags are not present, or if red flags are flying, swimmers should stay out of the water completely.

Always respect the power of Mother Ocean. If in doubt, don’t go out.


Daren Jenner is a the Thailand Section Chief at the International Surf Lifesaving Association. islasurf.org
Phone: 081 747 7733 and +171 4465 4200
Feature extract from The Phuket News

  Photo gallery : Small waves? Big trouble!

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