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Yesterday, Monday 5 August 2013, will go down in the history books at Dungeons. Not because it was the biggest swell ever – there have certainly been bigger – but because it was one of the most perfect swells in living memory. It’s hard to put an exact size on it. Some surfers were calling it 20 foot, others 30 foot plus, but safe to say the sublime conditions enabled many of the takers to paddle in to the wave of their life.
Jemsav from swell.co.za looks at why this was such a special swell.
WHAT MAKES A PERFECT BIG WAVE SWELL?
By: Jemsav / swell.co.za
A simple barometer of how clean and precise any particular swell is going to be is to look at the wave period. Easy rule of thumb: the longer the period, the cleaner the swell. If it arrives at the same time as a wild, perpendicular short period swell, or a screaming onshore wind (duh!) then the long period swell itself may be clean, but the surf won’t be. However we’ll stick to the simple rule of thumb as a good one.
Longer period swells aren’t all bells and whistles, they do have a downside. Another way of saying “long period” is “low frequency”, so these swells can have a long wait between sets. A second consideration is that if your local is a bland beach, and there is no variety of swell arriving, you could find yourself staring at one giant straight hander.
If you can deal with those two terrible downsides (left field suggestion here: drive to a better suited beach, apply extra sunscreen), then the upside of a long period swell is that the waves will be cleaner, they will wrap more, focus onto headlands and reefs better, and they will shoal more.
Once a wave has moved out its fetch, the motion of the wave train will clean up the swell as it moves. Smaller waves decay or get incorporated into bigger waves. The lumps are ironed out. Longer period swells pass more easily through opposing winds – although for our south swells in South Africa, that isn’t a major consideration.
Large swells like the one that hit the Cape yesterday with periods in the 18 to 20 second range are not particularly common in ZA – there’s only so much distance between us and South America. A big 19 second swell like this one has had its energy added as far away as we can hope. And a 5m swell at 19 seconds along our coast is a very good hand. It’s like getting dealt a pair of aces in your favourite card gambling game. Add to that light local winds and no competing swells, and you’re sitting with four of kind. It’s time to cash in.
Some swell stats from Monday and Tuesday in Cape Town:
The swell peaked at 5.38m at 11 o’clock at night on the 5th (last night)
The period peaked at 18.91 seconds at 5pm on the 5th (last night)
Swell direction was 235 degrees
If you thought the video was rad, just wait till you check out our exclusive Dungeons gallery featuring some of the best moments from yesterday’s massive swell.