Submarine Hull - Dive Depth

Dive Depth

The dive depth cannot be increased easily. Simply making the hull thicker increases the weight and requires reduction of the weight of onboard equipment, ultimately resulting in a bathyscaphe. This is affordable for civilian research submersibles, but not military submarines, so their dive depth was always bounded by current technology.

The World War One submarines had their hulls built of carbon steel, and could not submerge below 100 metres (328 feet). During World War Two, high-strength alloyed steel was introduced, allowing for depths up to 200 metres (656 feet). High-strength alloyed steel is still the main material for submarines today, with 250-350 metres (820 to 1,148 feet) depth limit, which cannot be exceeded on a military submarine without sacrificing other characteristics. To exceed that limit, a few submarines were built with titanium hulls. Titanium is stronger and lighter than steel, and is non-magnetic. Titanium submarines were especially favoured by the Soviets, as they had developed specialized high-strength alloys, built an industry for producing titanium with affordable costs, and have several types of titanium submarines. Titanium alloys allow a major increase in depth, but other systems need to be redesigned as well, so test depth was limited to 1000 metres (3,281 feet) for the Soviet submarine Komsomolets, the deepest-diving military submarine. An Alfa-class submarine may have successfully operated at 1300 metres (4,265 feet), though continuous operation at such depths would be an excessive stress for many submarine systems. Despite its benefits, high costs of titanium construction led to abandonment of titanium submarines idea as the Cold War ended.