The small bathyscaphs Trieste and Deepsea Challenger managed to descend in 1960 and 2012 , respectively, to the bottom of the Mariana Trench , about 11 kilometers deep, the deepest known point in the oceans.
These devices were specially built for this purpose and their design differs greatly from that of large submersibles , especially military ones, designed to silently transport heavy loads and numerous crew members . In general, most of the latter cannot go below 500 or 600 meters.
However, at that depth, the pressure is about sixty times greater than at the surface. Thus, these devices are built with materials that have a great capacity for compression and expansion , which can be adapted to descending or ascending maneuvers.
In general, the hull of larger submarines is a double structure that is built in a cylindrical shape and in flexible steel. This is usually the case for NATO. US Virginia-class attack submarines employ the HY-100 variety, which is both ductile and highly rugged . The Russians, for their part, have used titanium for some of their models, stronger and lighter, although less elastic. However, in other cases, especially in China, fiberglass has been chosen.
On the other hand, the rounded shapes better support deep dives, as the water exerts the same pressure on all sides of the submarine . In addition, their decks are not glued to the hull, but are suspended from cables at a certain distance from the hull, otherwise they would be seriously damaged when the ship carried out a prolonged descent.
Image: US NAVY
