Believable?
Believable?
Does anyone know the total number of ships of these classes existing in the world today?
If 200 ships represents 10% of the total, I really doubt the statictic. If 200 represents 0.1% it gets to be sort of believable.
Ships sink all the time & don't really make the news unless they cause a major oil spill or some other event. The crew of most ships are mostly foreigners and are primarily loners of some sort to choose that life. I doubt the loss of a ship will all hands would be front page news, esp. since the exact time & date would not be known with any certainty. More like a disappearance.
The Smeeton's sailboat was running in the center of the Atlantic with following seas of 60'-70', when the huge swells began to break and pitchpoled ('end-oed') the yacht. Mrs. Smeeton was at the tiller and would have been lost if Smeeton had not caught sight of her rain slicker in the water next to the boat when he came on deck.
This incredible story, and two others, can be found in a book called "Great Voyages In Small Boats". The breaking waves were attributed to 'shoal water' of 100' depth in the middle of the Atlantic.
The one man that lived said it happened so fast he thought he tripped and fell overboard. When he looked around the boat was upside down. Lucky he was found alive. Another was found dead and my son-in-law was never seen again. My daughter is here on Maui now for the Holidays trying to cope with it all. Prayers are welcome.
by Charles Thrasher, Bluewater staff
Bluewater's Newsletter #7 - Waves, wind & weather : Rogue Waves
The imaginative cartographers of the Middle Ages labeled much of the Atlantic the "Sea of Darkness" and warned mariners: "Here there be monsters." The oceans are mostly charted now and imagination has succumbed to knowledge but the monsters remain; brief, fleeting beasts with an existence as ephemeral as a mayfly but savage enough to sink a modern ship with a single blow. Rogue waves. Even the name connotes rampage and destruction like the charge of an outcast elephant. Like the rogue elephant, their appearance can be abrupt and devastating.
A rogue wave is the coincidence of several wave trains, the crest of one train superimposed and amplifying others. The typical life span of a rogue is measured in seconds. Abruptly they heave themselves above the surrounding waves and abruptly they dissipate, but within that brief span of coincidence a rogue can rise to monstrous heights.
The existence of a rogue wave is predictable only as a statistical probability - the percentage of probability that a wave of a specific height will occur within a specific area during a specific period of time, typically a period of years. That's not much comfort for a sailor looking warily over his shoulder for the sudden onslaught of a rogue. One thing is obvious: big seas breed bigger rogues. And the seas are getting bigger.
For the last 20 years a British ship has been anchored off Land's End, Cornwall, its crew patiently measuring the heights of endless waves. In those 20 years the average height of storm waves buffeting the anchored ship has risen from 39 feet to an intimidating 57 feet. (God alone knows how they manage to keep a crew onboard.) More typical wave heights have increased from 7.4 feet to 9 feet. The cause of this increase is still unknown.
How big are really big waves? In 1966 the passenger ship Michaelango was struck by a wave that stove-in ports 81 feet above her waterline. The bow section was flooded and three passengers killed. In 1965 the heavy cruiser USS Pittsburgh had 90 feet of her bow torn off by a wave. In 1933, the U.S.S. Ramapo reported the largest wave ever accurately measured at sea - 112 feet. The largest wave until Halloween, 1991.
It was the storm expected once every 10,000 years. A low-pressure system stalled off the coast of Nova Scotia. All the elements necessary to create massive waves were present - a wind of 70 knots blowing across unobstructed water for a prolonged period. These elements - wind strength, fetch and duration - resulted in waves reliably measured at 150 feet! Over a thousand miles away the residents of Melbourne, Florida gathered on their boardwalk to watch 15 foot surf thunder against the shore.
Oddly enough, the strongest winds don't create the largest waves. Winds in excess of 70 knots begin to topple waves and 100 knot winds will flatten them. Wind, however, isn't the only force that can make a wave dangerous. A strong current running opposite the direction of wave propagation can both heighten and steepen waves. There is a place off the pitch of Africa where a strong opposing current, huge waves and heavy shipping traffic intersect. It's a place where ships are known to vanish silently with all hands.
I mentioned hat the height of a wave is determined by three factors - wind speed, fetch and duration. In the Southern Ocean the fetch is almost endless, encircling the entire planet. The waves generated by that ocean are formidable. When the powerful Agulhas Current opposes these waves, the results are phenomenal.
The Agulhas Current is similar to the Gulf Stream and the Black Current (Kuroshio) of Japan. All are western boundary currents, among the most intense of ocean currents. The Agulhas can attain a velocity of eight feet per second driving south along the eastern coast of South Africa. When it rounds the Cape of Good Hope, the current is channeled by the steeply sloping continental shelf of Africa into the prevailing westerly winds of the Roaring Forties and their attendant waves. A strong current suddenly opposes large waves driven by relentless winds across a vast ocean. Conditions are ideal for the formation of rogue waves of staggering height.
A breaking wave can exert considerable pressure, as much as one ton per square foot. Imagine the damage resulting from a 100 foot wave breaking on the bow of a modern ship. She can founder, her buoyancy negated by the weight of water shipped on deck, or her bow can be holed. But at least a rogue wave is something a watch officer can see, and perhaps take steps to mitigate the damage.
The most alarming rogue may not be the crest at all but the trough. Where the troughs of numerous wave trains coincide, huge holes may suddenly appear in the ocean. Rogue troughs are secretive beasts and rarely seen. Their inverted profiles make them even more elusive than rogue waves. A ship's bow may fall into an enormous hole without warning. Driven by gravity and momentum, the bow may dive so deep it never rises. A modern ship with all the imaginable safeguards can go down before there is time to broadcast a Mayday.
Not all rogues are monstrous and alien. You can find them in your bathtub or the Intracoastal Waterway. Waves reflected from a vertical surface (like the sides of your bathtub or the concrete bulkheads that often form the banks of the ICW) lose little of their energy. Recent research indicates that when the crests (or troughs) of both the original and reflected wave are exactly synchronized, even though they're traveling in opposite directions, a wave can result that's taller than the sum of the individual waves. In other words, a true rogue. Rogues are likely to form in the lee of islands where waves, refracted by the island, rejoin at an acute angle.
There is at least one thing easily learned from the study of rogue waves - avoid the conditions likely to create them, especially a strong current running contrary to heavy seas. One excellent example is the Gulf Stream during a strong northerly wind. The actual danger in such conditions may be much greater than you might assume from a marine weather report.
Hogwash! ...Talk about a hoax!
Al Gore, the inventor of the Internet said that he invented monster waves by accident when he invented global warming?
Come to think of it, Froude numbers aren't to neighborly either.
"seiche
n.
From Swiss-French. A natural, standing wave in the water of a lake, bay, etc., caused by changes in atmospheric pressure, seismic disturbances, winds, waves, tides, etc.: it continues after the generating force stops."
These are different from "soliton" waves, which are another story altogether.
--Boris