Massive Atlantic Wave DOESN'T Set Record

Ben Freeston

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Updated 1089d ago

A record breaking 62ft monster wave was recorded in the Atlantic recently. At least that's according to the headlines. Except it's not true. We already know there have been waves bigger than 62ft in the Atlantic - we've even seen GMAC and crew surfing them. So what's going on?

How do wave buoys measure waves?

To qualify the story correctly you'd first have to mention that this is the record for a wave recorded by a wave buoy. Given how much debate we have about measuring waves this is a much more interesting story for the science minded surfer. These things are designed to measure waves right? Well certainly they do a better job than a few surfers drawing photoshop lines on photos of giant Nazare, but even they don't have a perfect system. A wave buoy is just a jumble of electronics in a watertight can anchored to the seabed on a flexible chain and rope anchor. To measure a wave we need to know the height of this wavebuoy above the seabed, or water level at the peak and trough of a wave. And to do this with a sensible degree of precision we'd want something fixed to measure the wave buoy's distance.

This is much more difficult than it sounds. Perhaps the most obvious answer would be GPS, but this has struggled with accurate altitude so hasn't been widely used to date. Instead the easiest and most popular option to deploy is a wave buoy fitted with the same kind of accelerometers you'd find in a mobile phone. These track the changes in acceleration as the buoy rises and falls with passing waves. If you know acceleration and time you know speed. If you know speed and time you know distance. It's remarkably simple and, on average, remarkably accurate. But there's the rub: For measuring a single individual wave the process isn't perfect and this error grows bigger in the extreme conditions of the largest waves. Instead the standard approach is to measure 'significant height'. This is the average of the largest third of all the waves over (in the case of the wave buoy) 20 minutes. This is the same number that you'll see on your surf forecast. That's what wave buoys typically, reliably report and that's what ACTUALLY happened here.

A typical wave buoy with a great view mooring in Alaska in (unusually) calm waters.

A typical wave buoy with a great view mooring in Alaska in (unusually) calm waters.

© 2019 - AOOS

The Real Story

So rather than a single giant wave of 62ft the real story is actually more interesting. What was recorded, in 2013, in the cold, wave rich waters between Iceland and the UK - was a succession of waves over 20 minutes of which the AVERAGE of the largest third was a record breaking 62ft. Splitting hairs? Definitely not. What we also know is that the largest wave over time is likely to be up to twice as large as this 'significant height'. That's a potential 124ft wave in this swell, which would comfortably top previous records: The 78ft wave GMAC rode at Nazare. The 1958 Tsunami in Alaska. The laser measured Draupner wave confirmed at 84ft.

Of course we can't confirm this value but we're almost certainly still well shy of measuring, let alone finding and riding, the largest waves on the planet.

Significant Height (green) versus Max Height (Black) for 2014 Hercules in shallow water in the UK. You can see the high variability in maximum height and that the largest wave is almost twice the significant height.

Significant Height (green) versus Max Height (Black) for 2014 Hercules in shallow water in the UK. You can see the high variability in maximum height and that the largest wave is almost twice the significant height.

© 2019 - Channel Coast Observatory