Submarines are amongst the most complex engineering marvels of this era. Today these crafts can alone steer the course of a war. A meagre knowledge that you have one of these, is enough to send a chill down your enemy’s spine.
Today’s Submarines are a result of almost 30 decades of perseverance and incremental growth. The first submarine was built in 1720 by Yefim Nikonov. This single manned, human-powered craft laid the foundation stone for submarines. Soon after this, the Americans came up with yet another human-powered design called ‘Turtle’. These crafts were plagued with lack of power and could not reach significant submerged speeds.
It was only in 1887 a boat christened as Nordenfelt III could reach a submerged speed of 4 knots with its coal-powered steam engine. Over the years people have tested various methods to propel these boats. As technology improved, human power for propulsion was gradually replaced by, coal, gasoline, diesel, batteries, hydrogen-peroxide, fuel-cells to nuclear power. Today’s boats can touch submerged speeds of 30 knots. The fastest amongst the lot is Papa Class, built by Soviet Russia. Papa Class can reach submerged speeds of 45 knots.
The hull-form has also changed significantly over the decades. Early boats were spherical shells. These early hulls were suitable for only a single passenger and could be operated over a small range. These hull forms caused major hindrance to its sea-keeping. Today’s submarines are optimised for submerged cruising. Teardrop hull increased the underwater speed and had a smaller acoustic signature, making detection by sonar more difficult. Another advantage was that the entire bow could be used to house a sonar for the submarine’s own hunting of opponents; the forward hydroplanes are located aft of the sonar array, or on the sail (conning tower in older boats) so as not to interfere with the sonar.
The rapid change in power generating technology has not only lead to an increased speed but has also increased its endurance at sea. The advent of diesel-electric propulsion along with AIP (Air-independent propulsion system) had a significant impact on submarine’s endurance but nuclear power proved disruptive. Nuclear Power submarines can virtually go on for their entire lifetime without the need of refuelling. Their number of diving days are restricted only by their onboard supplies.
Submarines diving depth has increased because of better steel which provides higher strength. World War – 1 submarines had their hulls built of carbon steel, and usually had test depths of no more than 100 metres. During World War 2, high-strength alloyed steel was introduced, allowing for depths up to 200 metres. High-strength alloyed steel is still the main material for submarines today, with 250–350 metres depth limit. Still, an urge was there to increase the diving depth. Increasing the thickness of plate was not viable as increased thickness resulted in increased weight which would result in compromise of the boats other abilities. So the ambitious Soviet Russia built a few submarines with a stronger metal, with TITANIUM to achieve higher diving depth. This significantly escalated the cost which led to the abandonment of the programme. Advances in nanotechnology and material science may free the future submarine designers from worrying about steel weight. Nano Aluminium Composite found by researchers in USA has shown an improvement of 150 percent in tensile and yield strength over untreated aluminium. This nano-treated aluminium can be an extremely efficient substitute for making aluminium hulls, aluminium superstructures and various other ship structures where light weight and high strength are highly desirable.
A submarine is considered most lethal because of its stealth and payload carrying capacity. As material science improved over the years it aided in developing non-magnetic steel thereby leading to a decrease in a boats magnetic signature. Degaussing technique is adopted to lower it. Today technology allows one to predict a boats magnetic signature and take countermeasures accordingly. Submarines are also detected by their noise. Various methods like the application of vibro damping coating on hull surface, to coating the Machinery with rubber acoustic-deadening buffers to minimize detectability by sonar. Apart from these huge cost incurring tech, the designers have taken steps to optimize the bend radius of pipes to minimize noise. Even engines are redesigned to operate at during silent running. Utmost care is taken by designers to ensure that air bubbles are not formed while launching a torpedo.
Today boats can carry all sorts of payloads ranging from mines to torpedoes to cruise missiles to SLBMS (submarine-launched ballistic missile). These SLBMS are reported to have a range of 10,000 km. These SLBMS can carry nuclear warhead on them. Torpedo with a range of 50km and speed of 50kt is developed by Whitehead Alenia Sistemi Subacquei.