During a raging storm, at a relatively shallow depth, each passing wave will be clearly felt on board the submarine. Under such circumstances, a particularly large wave, absolutely suddenly, without any warning, can pull a huge multi-ton vessel to the surface .
The consequences may not be limited to the loss of control over the situation, possible damage, both internal and external. If we are talking about a device that performs a military mission, the boat can become an ideal target , as soon as it is spotted by the enemy.
In 1805, the Irish hydrographer Francis Beaufort has developed an empirical scale , which connects the wind speed with observed weather conditions .
The scale has passed a difficult and long development path, based on previous works (including the work of Daniel Dafoe, published a century earlier). In the 1830s, the scale was officially adopted.
In fact, the scale includes 17 points, but points 13-17 are used in exceptional cases – with tropical cyclones. Therefore, formally, the scale is limited to 12 points , and in expanded form is used only in Taiwan and mainland China, which often suffer from typhoons.
The scale determines the ratio of wind speed at a height of ten meters above the surface of the water and the height of the waves in the open ocean.
So, 10 points on the Beaufort scale correspond to a wind speed of 90-100 km / h and waves with a height of over 12 meters . Such conditions definitely cannot be called favorable. The waves in the ocean will move at a speed of more than 55 km / h, the period between the waves is 14 seconds, and their length is about 210 meters.
The action of the wave propagates down from the water surface
and is presented in the form of a circulation movement. A depth equal to half the wavelength is called its bottom, where there is essentially no circulation movement . Therefore, to avoid rocking, the entire submarine should be below this depth.
That is, taking into account the fact that the typical height of the submarine is
15 meters from the keel to the tip of the upper part, with a storm of 10 points
on the Beaufort scale, it is enough for it to be at a depth below 100-120 meters .
Even a hurricane or typhoon will not make the wavelength much longer,
but it will be able to increase their height (more than 15 meters).