Sailors' Tall Tales
For as long as men have gone to sea, they have told stories of monstrous waves — single walls of water that rose from nowhere, towering far above the surrounding seas, and swallowed ships whole. Oceanographers dismissed these accounts for most of the 20th century. The prevailing mathematical models of ocean waves, based on linear wave theory, predicted that waves more than twice the height of the surrounding sea state were vanishingly improbable — a once-in-ten-thousand-years freak. In practice, the models said, waves this extreme simply did not occur.
Sailors knew better. But nobody had ever measured one.
New Year's Day, 1995
The Draupner platform is a gas pipeline support complex in the North Sea, roughly 160 kilometres south-west of the tip of Norway, standing in about 70 metres of water. It was fitted with state-of-the-art instrumentation, including a downward-pointing laser rangefinder mounted beneath the platform deck that measured the distance to the sea surface every 0.5 seconds.
On 1 January 1995, a severe storm was battering the North Sea. The significant wave height — the average of the highest third of waves — was approximately 12 metres. Rough, but not exceptional for a North Sea winter storm.
At 15:20, the laser recorded a single wave with a crest-to-trough height of 25.6 metres (84 feet). It rose 18.5 metres above mean sea level. It lasted roughly 12 seconds. And then it was gone.
Before the Proof: MS München
The Draupner measurement vindicated decades of anecdotal evidence. Perhaps no case was more compelling than that of MS München, a 261-metre German LASH carrier that vanished in the North Atlantic on 12 December 1978 with all 28 crew.
The München was one of the most modern and seaworthy cargo ships afloat. She sent a single distress signal, then silence. Despite a massive search involving over 110 aircraft and 80 ships, almost nothing was found. The few pieces of wreckage recovered told a chilling story: a starboard lifeboat davit had been wrenched outward by extreme force — and it was mounted 20 metres above the waterline. The forward mast was found crumpled as though struck from above.
In 1978, no wave model could explain damage at that height. After the Draupner measurement, the explanation became obvious.
The QE2 Encounter
Just nine months after the Draupner measurement, on 11 September 1995, the ocean liner Queen Elizabeth 2 encountered a rogue wave during Hurricane Luis in the North Atlantic. Captain Ronald Warwick described seeing a wall of water on the radar screen and thought it was a cliff: "It looked as though we were heading straight for the white cliffs of Dover." The wave, estimated at 29 metres, struck the bow and briefly submerged the foredeck. The ship survived, but the encounter underlined that rogues were not just a North Sea phenomenon.
How Rogue Waves Form
The Draupner measurement triggered a revolution in physical oceanography. Researchers identified several mechanisms that can produce rogues:
Constructive interference. In a chaotic sea state, waves of different lengths and speeds travel in different directions. Occasionally, by pure chance, several waves align and their crests stack. The combined wave can be far larger than any individual component. This is the simplest mechanism and probably the most common.
Current focusing. When waves run into a strong opposing current — such as the Agulhas Current off South Africa or the Gulf Stream — the current compresses wave energy into a smaller area, amplifying wave height dramatically. The south-east coast of South Africa is notorious for this effect; the area has sunk numerous ships.
Nonlinear effects. In certain conditions, waves can "steal" energy from their neighbours through a process called modulational instability (also known as the Benjamin-Feir instability). One wave grows at the expense of those around it, producing a single anomalous peak. This is the most recent and most mathematically complex explanation, and is thought to be responsible for the Draupner wave itself.
The Toll
Between 1969 and 1994, over 200 supertankers and container ships of more than 200 metres in length were lost at sea. Many sank in circumstances consistent with rogue wave encounters — sudden catastrophic hull failure in heavy weather, often with no distress call. The European Space Agency's MaxWave project, using satellite radar altimetry, identified 10 individual rogue waves over 25 metres high in a three-week survey period alone.
Rogue waves are not rare. They are common. We simply couldn't see them until we had the instruments to look.
Further Reading
- Wikipedia Draupner Wave — Wikipedia
- Wikipedia Rogue Wave — Wikipedia
- Wikipedia MS München — Wikipedia
- Science Scientists Recreated the Draupner Wave in a Lab — ScienceAlert
- ESA Ship-sinking Monster Waves Revealed by ESA Satellites