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How demanding and hostile can the high seas be to shipping and what is a superwave.
Ask any mariner, who has experienced really bad weather, for his impression of the sea and the response will invariably include the word “respect”. When a ship is going through severe weather, the most common thought of those on board will be along the lines “why am I here?”
The sea is a demanding mistress and shows no respect for those who ply their trade on the world’s oceans. Over the years man has tried to overcome the effects of the sea by building larger and larger ships; but as we have seen with the MOL COMFORT, even very large ships are not immune to the effects of rough sea. Traditionally those on board could feel the effect the weather was having on a ship through the soles of their feet! Now, on the huge craft plying the oceans today, even in the worst weather, it is difficult to “feel” how the ship’s structure is responding. Some companies do recognise this and ask Masters to reduce speed in extreme weather; sadly, there are operators who put pressure on ship surveyors to maintain speed so that a schedule can be met.
Ships have always had to deal with the forces of the seas. Some are well equipped to do so, while others, usually smaller ships, prudently seek independent shelter if there is a heavy weather threat. Often it is not the ship that cannot withstand the weather, but those on board. People can be thrown as a result of violent ship motion, about; as happened when the Queen Elizabeth 2 encountered a huge wave in the mid-1990s resulting in many passenger and crew injuries. If it is not the personnel on board then the cargo itself can be the cause of problems. Cargo can shift, causing the ship to heel over; or goods badly loaded into a container moves within it, resulting in mutual damage.
Until recently, non-mariners had to rely on seafarers’ tales about extreme weather. Now, on social media, it is possible to see at first hand the effect of extreme sea; for example, just type in “rogue wave” on You Tube and the viewer will get a very good idea what ships and their crews have to go through. It might be a good idea if every container packer, bulk cargo operative and shore employee of a shipping company had to view such material as part of their training!
The term “rogue” wave is applied to waves that are “large, unexpected and dangerous”. One of the first recognised incidents occurred in 1973 to the Bencruachan, a well found Ben Line ship that encountered a rogue wave off the coast of South Africa. Damage extended some 40 meters aft from the bow and the forecastle was depressed by about 21°. Since that incident many ships have encountered “freak” waves, but of course we only hear about those who survive. Indeed, before the Bencruachan incident, the existence of freak or rogue waves was considered to be a figment of mariners’ imaginations. The incidence of rogue waves off South Africa is well documented and Masters are advised to avoid certain areas.
By definition, NOAA scientists call rogue waves “extreme storm waves” and consider they are waves that are greater than twice the size of surrounding waves. These “superwaves” can occur in any open ocean, but there are few observations in existence that can be used to give mariners some indication of their certainty in bad weather. Oceanographers postulate a number of reasons why they occur and the NOAA web site offers a clear demonstration of what scientist think.
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> views on How does heavy weather affect modern seagoing vessels? Ships are becoming safer, of that there can be little doubt. However, there are still instances where severe weather has a seriously bad effect on modern ships. Arguably, the loss of containers overboard due to “extreme” weather still occurs. Recently a very large container ship is said to have lost some 500 units in “severe” weather. The question must be asked “was such a loss due to the severity of the weather, or ship design?”
Those who go to sea know all too well just how demanding the ocean can be; there are few if any occupations where just standing up can be marine surveyors