Wednesday, July 11, 2012

Driven Forth Before the Wind – The Rogue Wave Zone off South Africa

As mentioned in the last post, the area around the coast of South Africa is referred to as a major Rogue Wave Zone. Anciently, sailors often whispered of monster waves when ships mysteriously sunk but, until now, no one quite believed them. However, recently, with filming from space by the European Space Agency, these freak waves have been spotted as tall as ten-story buildings!

Although of different sources, Tunamis and Rogue, or Giant, waves (also called Freak, Monster and Maverick waves) have the same devastating power. The principal difference between them is that rogue waves rarely hit land and when they do they invariably get classed as Tsunamis without further distinction.

Rogue waves generally go unnoticed by the general public, except for the occasional extraordinary stories told by people who have experienced such phenomena. As an example, in 1995, the cruiser liner Queen Elizabeth II met a 95-foot high rogue wave, which Captain Ronald Warwick described as "a great wall of water… it looked as if we were going into the White Cliffs of Dover." Cargo ships, tankers, containers and passenger ships where disappearing for no apparent reason leaving little or no trace in these Rogue Wave Zones. Ships had been disappearing in mysterious ways ever since history has been recorded and until recently such disappearances where considered nautical myth of legendary origins.

Rogue waves have, however, recently become the subject of some very serious study. Preliminary results diagnosed the cause and Merchant companies the world over were soon aware of the results of the studies...the news was alarming. The cause of the alarm? Scientists had diagnosed the reason for the loss of the ships, normally built to resist "normal" sized storm waves (± 50 feet), as being the result of rogue waves of exceptional size and force, often as much as twice or three times the height of the average storm wave.

Merchant companies, and even countries, were confronted with the fact that their ships, super tankers of more than 250,000 tons and container ships of 650-feet length, were not as invulnerable as they believed. The prospect of having to pay billions in rebuilding their merchant fleet caused panic.

Monster Rogue Waves are, for the time being, so unforeseeable and so strong (100 tons/M²) that a 100-fot wave can sink a ±250,000 ton tanker in a flash, knocking holes straight through a ship's hull like a battering ram. Monster Rogue Waves can also seriously damage a ± 800-foot high North Sea offshore rig, the equivalent of a seventy story skyscraper!

Once considered freak events, the acceleration in communications and the access to satellite images from agencies, such space-reporting is proving that Rogue Waves are in fact quite common. Scientists are able to establish risk zones around the globe where such phenomena frequently happen. As a result Merchant companies are now able to reroute their shipping to go around these regions, save billions in insurance and avoid having to reconstruct their fleets.

One famous example of a zone where Rogue Waves are frequent is just off the coast of South Africa where the Agulhas Current runs Northeast/Southwest down from the Indian Ocean. This current is a warm water current and when it is met with an ascending cold water current, originating from the Southern Atlantic/Antarctic ocean conditions are ideal for the creation of Monster Rogue Waves. This is because in this area 1) one or two waves of lesser power and dimensions collide in open sea causing a compression that has no issue but upwards, and 2) where underwater currents clash and prevailing winds change direction and tides.

This condition has always existed around the tip of South Africa, as noted by early Portuguese sailors which, when encountering such waves, called them freak or monster waves—but very few survived the experience in the “Graveyard of Ships.” 

It is interesting that modern man (historians and scholars) so glibly claim that the Lehi Colony of “landlubbers” sailed westward around the tip of Africa and across the Atlantic to the Land of Promise. Such an event in 600 B.C. would have been not only improbable, but incredibly dangerous—so much so, that experienced seamen 2000 years later, found it nearly impossible to make such a trip until they eventually learned (after the loss of numerous vessels in the “Graveyard of Ships”) how to sail around Africa.

(See the next post, “Driven Forth Before the Wind – Eastward Across the Indian Ocean,” to show the improbability of a wind-driven ship broaching the strong Indonesian currents and winds)               

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