For something to float on water, its density must be lower than that of the liquid. This is the basic principle that enables boats and ships to float comfortably on water. Submarines had to be designed in a special way that would enable them float or dive into oceans and stay there for long periods. A principle was developed by a scientist called Archimedes state that for a body to be either fully or partially submerged in water, there is equal force pushing it upwards equal to the weight of water displaced. The sub had to look for a mechanism that will enable it gain or lose weight for enabling its stay in water.
Submarines are built with two trim tanks with one at the front half of the boat and the other covering back half. The sub needs to maintain a stable position creating the need for these tanks. Weight can be affected by activities within such as movements and depletion of utilities. Trim tanks are filled with seawater for the vessel to gain additional weight enabling it to go underneath. Amount of water inside these tanks determines its overall weight therefore how deep it goes. Water held here is expelled to be replaced by air which makes the sub lighter to enable reduction in depth explored.
Quantity of air or water are regulated to ensure that the right depth is maintained. Ability to submerge/float is determined by the buoyancy controlled by these tanks.
Steering of a sub is guided by use of two sets of planes which determine motion and direction. Sail planes are located at the top side to control side movements with stern planes located at the back near propellers responsible for up/down motion. Some submarines have their sail planes located at the front although they still serve the same purpose of guiding on direction. They are connected to control tower enabling them to interpret signals at a fast speed. With these many accidents with sea nature is avoided during long stay in ocean/sea patrol.
The occupants would not survive in water because of great water pressure brought by depth covered. It is because of this phenomenon that they are constructed with two strong hulls. One is on the inside to prevent any pressure from reaching the crew and the other providing cylindrical shape to the vessel. Trims holding water are located between them ensuring that they are protected from direct contact with salty seawater. Inner hull is still responsible for ensuring that extremely low sea temperature does not affect subs components/occupants’ comfort.
Subs are usually used by army for patrols creating the need for them to stay in water undetected for up to six months. This means that there is no time for refueling. Before advancement of technology, this used to be a major challenge with Germans having to travel with an additional submarine for fuelling only. However, today they are powered with nuclear energy where a small quantity of Uranium is capable of powering the huge vessel for months with no need of going to its harbor. Enough heat energy is produced to produce steam for propelling huge turbines together with launching missiles from big depths.
Inside deep waters, oxygen requirements can be a challenge but this problem has been addressed thanks to science. Engineers can run electricity through water to separate it into its different components Oxygen being one of them. This Oxygen is used for breathing and running of machines inside the submarine. Crew members also pack enough food supplies both canned and food requiring self-preparation thanks to chefs that are always on board.
Surveillance of surroundings above is crucial for its military missions, and they can conveniently do this with the use of a periscope which is attached to the sub’s upper body. It is a long pipe that rises above water to show images and made of a series of lenses/ mirrors which reflect images to screens inside the submerged vessel. Innovations are being put in place to bring use of optic fiber which will improve surveillance without physical components reducing risks of detection. With all these properties combined with technological advances, submarines can safely stay underwater providing crucial security guarantee by averting potential enemy danger.