22 Seconds ...

Twenty two seconds: the time it takes to take a leak, or to walk to the fridge and back with a drink. But we're not talking every day time. We're talking about a swell moving at 35 metres per second (126km/h).

We're talking about a wave 775 metres long, with energy extending 368 metres into the ocean deep. We're talking about a wave with almost unbelievable power for its size - a 15 foot swell in the ocean that becomes an angry, spitting 30 foot axe murderer at the shore.

The anatomy of the 22 second swell that arrived late on Big Wednesday, 19 March 2014, will always be remembered - in my archive anyway - as having the longest period (and therefore biggest energy) I have ever seen.

The swell arrived late, but worth waiting for. In Cape Town, it showed 19.9 seconds. The true forecast showed a peak of 21.6 seconds for the first and fastest sets - the forerunners - that hit the West Coast on Wednesday evening.

Wednesday evening showed signs, but the grunt was still to come. Photo Brenton Beach

Driving past Camps Bay at 7pm on Big Wednesday, I could see 15 foot lines grind through off the backline at Glen Beach. But by 11pm, a friend and I witnessed something special. Standing at the La Med side of the bay, we gaped at the furious mayhem that spread out from the boulders below us to the bay beyond.

We were watching a World War II bombing raid metres from the shrapnel. The noise was deafening as roiling, tsunami-like surges burst and cracked and roared over the rocks, followed by another white-water wall sweeping from giant sets breaking in inky darkness a mile offshore. We could dimly see the blurred white detonations at the edge of the glow cast from the beachfront lights.

We were watching a World War II bombing raid metres from the shrapnel. The noise was deafening as roiling, tsunami-like surges burst and cracked and roared over the rocks, followed by another white-water wall sweeping from giant sets breaking in inky darkness a mile offshore. We could dimly see the blurred white detonations at the edge of the glow cast from the beachfront lights.

But right in front of us, we could not only hear and see explosive bursts of spray cutting the night sky like foam bullets, but we could feel each jarring "whump" with our feet as shockwaves shivered the granite.

To witness such natural violence was awesome and inspiring. No-one knows how big it got on Wednesday night. Judging by the midnight vigil at the foot of the Twelve Apostles, that Wednesday evening and Thursday morning straddled each flank of a sharply angled upturned V, with a peak of 50 foot or more taking place between 11pm and 3 in the morning.

Wednesday evening showed signs, but the grunt was still to come. Photo Brenton Beach

According to boffins, the maximum wind-generated swell reaches 23 seconds. It's unlikely we will see another one like this in a long time.

A forecasted height of 15 feet at 22 seconds in the open ocean means heights of 25 feet from trough to crest. But when these ocean orcs begin to rumble over the sea bed as they shoal towards shore, they compress into a moving mountain range, far bigger for those paddling in and out of yawning valleys.

At the peak of this swell, which took place out of sight in the middle of the night, there would have been wave faces of 50-70 feet at places like Tafelberg, or SW Reefs. By 4.30pm out at Dungeons, it was a messy 10-15 foot. Although it was building rapidly, there was a leftover westerly bumpy on it, and daylight was running out. Gratification was delayed.

The big wave crew, who had been swarming all over Hout Bay during the afternoon, did not have much time. They managed a few as dusk was fading into nightfall, but the first 20-25ft sets appeared too late.

Boom. An L-Bomb goes off in the deep, more than 2,000 nautical miles from Cape Town.

What's an hour or two after a three-day journey across 2000 nautical miles of open ocean? The generating storm peaked east of the Sandwich Islands off the bottom of South America early Monday. As the low pressure system deepened peak winds strengthened. At its peak, the pressure had reached 945MB and 70kts of wind was blasting in a fat sausage about 200 miles wide and 800 miles long, give or take. That's some fetch.

Thursday dawned a beauty. By the time the big wave crew were on it, the swell had settled into a thumping 25 foot swell that behaved more like 40 foot swell when it broke. It was a little buckled, and doubled up, as though another swell had been sown in among the set waves.

The swell peaked late Wednesday night, but Thursday morning was still scary. Photo Brenton Beach

The peak period had eased to around 16 seconds. But there was still plenty of juice to keep the guys honest. The grizzled local crew, including Simon Lowe, James Taylor, Jem Johnson, Andy Marr and Mike Schlebach, were looking for the bombs. Mad Mike Baleta and Simon Lowe practised a few "step-offs" in another long lull. Mike was jumping directly onto his board off the jetski, and trying to pull straight into the wave. He claims Simon used him as a test dummy, and he got a couple of beatings.

As Mike says: "The morning was 20-25 foot and huge but big and wild and with a huge amount of energy and volume. Simon Lowe and Jem Johnson were out there, and probably should have been towing. The swell was weird, with almost two directions, and with an immense energy. They were very hard to catch. I arrived a bit later. The bombs, the set waves, just wouldn't let us in.

"Most of the big waves that came through were not ridden. During the low tide, nothing happened for an hour. The afternoon cleaned up and was really fun, but again, really hard to hook the big ones. I have never been in waves like that, with such power. It was so powerful. Swell was beautiful, but it just wouldn't let us in."

The Durban guys were there in considerable force, including Josh Redman, who now must be considered almost a veteran by now after several trips to Hawaii, and numerous sessions at Dungeons. With him were hungry youngsters such as Slade Prestwich, Dale Staples, and young Koby Oberholzer, who were looking for some experience.

Local boys Mikey February and Matt Bromley were out, hooking into a few bombs. In the case of Bromley, it was more than a few. According to guys watching from the channel, he was a stand out, riding the lions shore of the spoils. While perhaps not hooking the bombs, he was riding flatout with total control, and ratched up an impressive tally.

Might as well feast on this one, because it's unlikely we'll see another swell like this for a long time.

Unless global warming has other ideas.