Rogue waves have long divided sailors and scientists. Some question their existence, other schools of thought suggest that ‘freak’ waves are actually more common than first thought.

But for those who have experienced a ‘rogue’ wave, towering over their yacht before wreaking havoc, there is little question over their potency.

There have been several incidences where ocean racing yachts have encountered unusually severe waves. Alex Thomson and Guillermo Altadill were rolled and dismasted in Hugo Boss, by what they reported to be a rogue wave some 82 miles off the coast of Spain in the 2015 Transat Jacques Vabre.

In 2010 Sebastien Josse and Jean-François Cuzon were airlifted from BT after it was struck by a huge wave some 210 miles north-west of the Azores. The pair were sailing in 30-50 knots of wind when “a hydrodynamic event of significance” hit the yacht, stoving in the coachroof and flooding the yacht.

BT was recovered and surveyed. What convinced the designers, Farr Yacht Design, that the destruction was the result of a so-called rogue wave, was that besides the coachroof breakages, damage was also seen in other areas that had undergone repeated significant loading during other races.

After analysing the yacht, they reported: “One can say in all seriousness that if the coachroof had been twice as strong we would likely still have seen damage, which gives some idea of how far outside the normal bounds this event was.”

Rolled single-handed

Sir Robin Knox-Johnston recalls being hit by a wave twice the size of the swell in the Southern Ocean in 1968: “The wind had been building for a while but was showing signs of easing so I went on deck to see whether it was yet safe to put up more sail.

“The swell was huge, 40-50ft, but that on its own is not a problem. However, as I looked astern I could see a monster [wave] coming towards me, a combination of the swell and sea, at least 80ft high, breaking at the top and stretching from horizon to horizon.

“It surged towards us and I knew I had no time to get below but I could not stay on deck or I would be washed away. I climbed the rigging and hung tight as the wave arrived and completely covered the boat.

“For what seemed an eternity there was me and two masts sticking up above the ocean, and then Suhaili bounced back to the surface. The 600ft of warps streamed astern had prevented her from surging forward and broaching.”

Solo adventurer Roger Taylor translated a new book on rogue waves, Anatomy of a Monster, from the original French. “I learned a lot, and will never look at a sea state in quite the same way again,” Taylor comments.

“I now understand immeasurably more about what is actually going on as the waves fold and unfold, and will, I think, be a better seaman for it.”

Taylor has himself twice been rolled by rogue waves: “My most extreme roll was during the 1974 Singlehanded Trans-Tasman Race, not far north of 40˚ South. It was a humdinger of a Tasman storm, and my 19ft sloop Roc had already been put on her beam ends once.

I was sitting below, and fortunately clinging on to the companionway ladder, when a second rogue took over proceedings. The world went black, a Niagara-type roar wound itself up, and there we were, spinning our way through 90 degrees, and then 180 degrees, and then… I really don’t know.

“I don’t know whether we went through the whole 360 degrees, or whether we came back up the same way. Upside down in a pitch-black washing machine, with sound effects to match, I lost all sense of orientation.

“What I do know for sure is that we reached 180 degrees. I had tomatoes preserved in glass jars under one of the bunks. The bunk tops came off, the jars fell and smashed on the robustly constructed coachroof.

“When Roc righted herself, more or less instantly, tomato goo and broken glass were dripping down on to me.

“Roc, despite her size, was a strongly designed yacht and she came through unscathed. She had a sliding hatch, though, and despite the double baffles and towels I had used to try to increase its water-tightness, the pressure inside the wave was enough to force a fair amount of water through the baffles. Since then I have only ever gone to sea with proper sealing hatches.

“I was certainly glad to have a sealing hatch when my junk-rigged Corribee, Mingming, met a bad wave in the Davis Strait, a hundred miles or so off the west coast of Greenland.

“We had been running north-west before a south-south-easterly gale for nearly two days, under bare poles. My Windpilot self-steering gear had kept us on track the whole time, with the wind a couple of points off the port quarter.

“Although a big sea was running, Mingming felt comfortable and I had no thoughts about launching my drogue.

“A characteristic of rogue waves is that they often appear at an angle to the prevailing wave train. This is often what makes them so dangerous.

“I was half-dozing in my one narrow starboard bunk when I took to the air. I can only surmise that a big wave had come in from the wrong quarter, pushing the stern round through the wind and bringing us beam on to the sea.

“In the process my leeward bunk was converted to a windward berth, and as we were put on our beam ends I went for a flight across Mingming’s tiny cabin. The trajectory was not far, but enough to break my rib against the corner of the chart table.

“Since then I have fixed webbing straps to my bunks so that I can lash myself in.”