The mystery of the 'dead water' that traps ships in the middle of the ocean

 

 In 1893, Norwegian explorer Fritjof Nansen launched an expedition to the North Pole, after which he became world-famous for breaking the northern latitude record. He was the first to observe a strange phenomenon during the voyage that puzzled scientists for more than a century. While sailing through the Arctic waters of northern Siberia, Nansen noticed that his ship, the Frame, suddenly stopped even though its engines were running at full speed. Fredjoff described the situation as a 'mysterious force' that had seized his ship, causing it to barely move. We tried to get out of this trap, sometimes we pushed around, we tried all kinds of strategies to avoid it but with little success," he later said. Nansen became the first person to observe this strange phenomenon and named this water trap 'dead water'. 

Salt layer of water

                

Eleven years later in 1904, the Swedish physicist and marine scientist Wigan-Walfred Ekman was able to identify this phenomenon and find the reason behind it. Ekman demonstrated in the laboratory the observation that in this part of the Arctic Ocean, waves are created between the layers of salt and fresh water below the surface that have different densities. They attributed this to the melting of glaciers, which creates a layer of fresh water above the ocean. This water is more salty and thick. However, during laboratory experiments, Ekman observed that these waves caused oscillations in the ship's speed. This differs from the observations of Nansen whose ship stalled at a constant and unusually low speed. Until now, no one has been able to explain these differences or fully understand how 'dead water' affects them. But an interdisciplinary team from France's National Center for Scientific Research (CNRS) and the University of Poitiers believe they have discovered the secret to both mysteries. To understand this phenomenon, a team of physicists, fluid mechanics, and French mathematicians used mathematical classification of various underwater waves and experimental image analysis at the 'sub-pixel scale'. In a paper published in the scientific journal PNAS in early July, he concluded that the wave speeds Ekman described were due to different types of waves acting on a sort of 'vibrating conveyor belt'. Works as

Due to this 'tape', the boats are moving back and forth.

Scientists also succeeded in combining Ekman's observations with Nansen's and claimed that this double effect was only temporary.

 He also published in his paper that in the end 'the ship manages to escape from this situation and reach the constant speed described by Nansen.'

Experts believe that this phenomenon occurs not only in places with glaciers but also in all seas and oceans where water of different densities meets.

This also happens in cold mountain lakes during the summer because the temperature is stable there and therefore the swimmers are less likely to drown," study co-author Jermaine Roussoc said in a statement to Spain's ABC newspaper. The danger remains.'

This trend is also seen at the headwaters of rivers such as the Orinoco in South America, due to salty seawater and river runoff, Rusiuk added.

Cleopatra                                  

Interestingly, the research was not conducted to unravel the mystery of what happened to Nansen more than a century ago, but to unravel a much older mystery.This work is part of a larger project investigating how, in ancient Greece, during the Battle of Aquarium of Actium (31 BC), Cleopatra's and Marco Antony's large ships, facing ships even weaker than Caesar's Octavius, disappeared. were done

Did Axio Bay, which has all the characteristics of a long dark chasm, sink the Egyptian queen's fleet in dead water?

This is the question French scientists asked themselves.

 'Now we have another hypothesis to explain this astonishing defeat, which was anciently attributed to a type of fish, the 'hooked baitfish.'