curve. That is, a rogue wave is a statistical improbability, but not an impossibility, and no freakish interaction is required to explain its existence.
Any of these effects might combine with other mechanisms (unknown or listed above) to produce superwaves.
There’s no lack of mention of big waves in the literature of small-boat sailing. Here is one from Joshua Slocum’s famous book Sailing Alone Around the World (available in many editions more than a century after its first publication):16
“My ship [the year was 1895] passed in safety Bahia Blanca, also the Gulf of St. Matias and the mighty Gulf of St. George [along the Argentine coast in the South Atlantic]. Hoping that she might go clear of the destructive tide-races, the dread of big craft or little along this coast, I gave all the capes a berth of about fifty miles, for these dangers extend many miles from the land. But where the sloop avoided one danger she encountered another. For, one day, well off the Patagonian coast, while the sloop was reaching under short sail, a tremendous wave, the culmination, it 27
More on Big Waves
A graph line of a superwave formed from a background of smaller, random waves. The enlarged wave may take energy from the adjacent waves on either side. The greatly enlarged wave may have a life of only a minute or two.
seemed, of many waves, rolled down upon her in a storm, roaring as it came. I had only a moment to get all sail down and myself up on the peak halliards, out of dan- ger, when I saw the mighty crest towering masthead high above me. The mountain of water submerged my vessel. She shook in every timber and reeled under the weight of the sea, but rose quickly out of it, and rode grandly over the rollers that followed. It may have been a minute that from my hold in the rigging I could see no part of the Spray’s hull. Perhaps it was even less time than that, but it seemed a long while, for under great excitement one lives fast, and in a few seconds one may think a great deal of one’s past life. No only did the past, with electric speed, flash before me, but I had time while in my hazardous position for resolutions for the future that would take a long time to fulfill. The first one was, I remember, that if the Spray came through this danger I would dedicate my best energies to building a larger ship on her lines, which I hope yet to do. Other promises, less easily kept, I should have made under protest. However, the incident, which filled me with fear, was only one more test of the Spray’s seaworthiness. It reassured me against rude Cape Horn.”
Here’s another account, this one from Alain Gerbault’s Flight of the Firecrest, first pub- lished in English in 1926:17
“It was a dirty looking morning on the 20th [of August, 1925] and the climax of all the gales that had gone before. It was the day, too, when the Firecrest came near to making the port of missing ships. As far as the eye could see there was nothing but an angry welter of water, overhung with a low-lying canopy of leaden, scurrying clouds, driving before the gale.
“By ten o’clock the wind had increased to hurricane force. The seas ran short and viciously. Their curling crests racing before the thrust of the wind seemed to be torn into little whirlpools before they broke into a lather of soapy foam. These great seas bore down on the little cutter as though they were finally bent on her destruction. But she rose to them and fought her way through them in a way that made me want to sing a poem in her praise.
“Then, in a moment, I seemed engulfed in disaster. The incident occurred just after noon. The Firecrest was sailing full and by, under a bit of her mainsail and jib. Suddenly I saw, towering on my limited horizon, a huge wave, rearing its curling, snowy crest so high that it dwarfed all others I had ever seen. I could hardly believe my eyes. It was a thing of beauty as well as of awe as it came roaring down upon us.
“Knowing that if I stayed on deck I would meet death by being washed overboard, I had just time to climb into the rigging, and was about half-way to the masthead when it burst upon the Firecrest in fury, burying her from my sight under tons of solid water and a lather of foam. The gallant little boat staggered and reeled under the blow,
until I began to wonder anxiously whether she was going to founder or fight her way back to the surface.
“Slowly she came out of the smother of it, and the great wave roared away to lee- ward. I slid down from my perch in the rigging to discover that it had broken off the outboard part of the bowsprit. Held by the jibstay it laid in a maze of rigging and sail under the lee rail, where every sea used it as battering ram against the planking, threat- ening at every blow to stave a hole in the hull.
“The mast was also swaying dangerously as the Firecrest rolled. Somehow the shrouds had become loose at the masthead. There was now a fair prospect that the cut- ter would roll the mast out of her, even if the broken bowsprit failed to stave the hole it seemed trying for. The wind cut my face with stinging force, and the deck was, most of the time, awash with breaking seas.
“But I was obliged to jump to work to save both boat and life . . .”
And finally, here’s an account from Jean Gau, which appeared in To Challenge a Dis- tant Sea:18
“Sometime during the night of February 27 [1965] the catastrophe occurred. “About three in the morning I heard a strange noise approaching my boat [a 30-foot Tahiti Ketch designed by John Hanna]. I could not believe my ears. What is happening? Probably nothing—or something. I thought: It must be a furious wave that is coming, head first, and about to tumble on deck? Instinctively I grabbed the side of the bunk. Suddenly in a terrifying din, like an explosion, an enormous wave hit the port side and tons of water fell on deck. I was thrown violently against the ribs of the boat, to be immediately covered by all sorts of items, sail bags, charts, books.
“Atom had capsized!
“Her keel now lay over my head!
“All openings were tightly closed at the time except for a small porthole on the after wall of the cabin. Through that opening a powerful jet of water now spewed into the cabin. My heart sank for I expected this to be the last blow. I remained breathless for seconds. ‘I am finished,’ was all that I could think of. I had suspected that one day I would meet at sea one of those ultimate waves that would bury my boat and me com- pletely. I now believed it was all over. Alone in the moving darkness, entangled and nearly buried under debris, frightened, unable to get up and help myself, succumbing to an acceptance of death, I was suddenly aware that Atom had righted herself! Her heavy iron shoe had saved us.
“In an effort to overcome my sense of distress and hopelessness, I decided that I had to get out of that cabin! Freeing myself, hurting and bruised, I hurried topside. A dreadful turmoil was raging about the boat. . . . Atom had been dismasted!
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“What a horrible sight—bowsprit, stumps of masts, spars, splintered booms, sails, and lines torn and tugging to leeward, all held by tangled shrouds and halyards. Gone, too, was the dinghy. All [this] had happened in a few seconds!”
All three of these sailors—Joshua Slocum, Alain Gerbault, and Jean Gau—success- fully overcame being swamped and damaged and, like good sailors, continued their voyages.
T
SUNAMISTsunamis are fast surface waves capable of traveling great distances. They are caused by seismic events and take some hours to cross an ocean so that warnings are possible if an alarm system has been set up. A tsunami, a Japanese word from tsu (port) + nami (wave), maintains significant energy levels until it finally breaks with catastrophic force in shoal waters. In Chile, on May 22, 1960, a severe undersea earthquake cre- ated tsunamis (pronounced ts nä me) that traveled to New Zealand, 6,000 nautical miles away, where they raised water levels almost 8 feet in some east coast ports.
In December 2004, an immense tsunami struck the coastal areas along the eastern Indian Ocean. More than 225,000 people were killed and huge breaking waves (up to 100 feet high) caused catastrophic damage along the coastal areas.
Generally tsunamis involve a series of waves that break on shore. In between the separate waves, the water is sucked out of coastal harbors and rivers. Out and in! Out and in! My friend Ross Norgrove was aboard his yacht White Squall in a small harbor on New Zealand’s east coast when the May 1960 tsunami hit.
“I remember it all perfectly,” Ross told me. “First we had a surge in the water level in the harbor. Then all the water ran out and the different boats were in the mud, some on their sides. The dumbbells were on the harbor floor, picking up fish. The smart people were running for the hills. I checked my anchor and then took off to high ground. Sure enough, in a little while the water came back and poured into the harbor higher than ever.”
By chance I visited Hilo, Hawaii, a few weeks after the same Chilean tsunami had struck the islands. Hilo had been the worst hit and had suffered waves up to 35 feet, which destroyed the waterfront. I remember being impressed by a long row of parking meters that were all twisted and bent and knocked flat.
But I am talking about shore damage. At sea the height of tsunami waves is only a foot or two and almost unnoticeable. Tsunamis out on the ocean can be ignored.
S
WELLWhen the weather changes and the wind moves away from a section of the ocean over which it has been blowing for some hours, the shape and character of the waves
become different. Without the nexus of a constant wind, the crests diminish in height and become more rounded and even-sided. This form of the sea is called swell, and can travel for thousands of miles.
Swell moves across the ocean from the area in which it originates toward a distant shore in trains, or groups of waves that can be thought of as bundles of energy. The velocity of a wave train is only about half normal speed, because at the front of the train some of the energy of the swell is used to put water particles into orbit. This causes the forwardmost waves to lose their energy and disappear. New waves appear at the back of the train, however, so the total number of waves is unchanged. Knowledge of this speed reduction is important, because forecasters use it to predict the arrival of waves from far-off storms.
“A wave group whose period averages twelve seconds will take two days to cross one thousand miles of open ocean,” writes Willard Bascom. An individual 12-second wave will take only half as long.19
The onset of pronounced swell is well known to hurricane watchers and small- boat sailors because it means that trouble is coming. The larger the swell, the bigger the approaching problem.
But enough inquiry into the quirky behavior of waves. As mariners we’re full of cu- riosity about the sea, but as small-boat sailors confronting foul weather our concerns are more immediate and practical. We want to know what to do about the conditions at hand or just ahead. That’s what we’ll explore next.
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