Submarines are fascinating vehicles that have the capability to take mankind into previously unexplored depths of our oceans. These watercraft have advanced in development as our technology has improved, allowing us to go deeper, further, and for longer periods underwater. Let’s examine some of these amazing underwater vehicles, how they are used and what benefits they offer to our modern society.
Submarines come in many shapes, sizes and forms, and can be used as weapons of war, exploration vehicles, scientific research vessels, tourism vehicles, commercial vehicles, and just for recreation. The purpose and intention of the submarine dictate its design and capabilities.
Submarines are very similar to spacecraft. They are vehicles that allow us to explore an environment that is hostile to us and without which we would not survive these unfamiliar and dangerous conditions. While spacecraft allow us to explore beyond our planet, submarines allow us to explore the depths of our planet. Many of these vehicles are interesting, intriguing, and ingenious in their invention, testament to man’s pioneering spirit!
History Of Submarines
People have been dreaming about visiting the mysterious underwater world for centuries. Our quest for knowledge and exploration is insatiable, and men have been wondering about what lies below the surface of the water since the early 1500s. There are reports of two Greeks who built a craft and successfully submerged and reappeared unscathed, not wet and with a lamp for light, still burning.
This was reportedly achieved in the river Tagus, near Toledo, with the Roman Emperor Charles V in attendance. Historical records are not clear if this event actually occurred or what the designs of the craft were that was used.
The first reliable information about a submersible was in 1620, invented by a Dutchman called Cornelis Drebbel, whose submersible was propelled by oars.
This was the humble beginning of the submarine, and improvements in design and available technology have resulted in the ever-improving submersible craft being developed.
The first military submarine was invented in America by David Bushnell in 1775 and was a single-person craft, but it was the first to use screws as a propulsion method rather than oars.
1. Human Powered Submarine
All the submarine designs that were built in the early history of this underwater craft were human-powered. The early vessels were powered by means of oars, which were manned by crewmen. Other members of the submarine crew were tasked with manually clearing the bilge.
Later versions of the submarine, including the famous Nautilis, designed by an American, Robert Fulton, who was living in France, was powered by a screw propeller rather than oars. This screw was hand-cranked by the crew. This vessel was intended as a warship and was intended to deliver naval mines for destroying merchant ships.
2. Mechanically Powered Submarine
A major advancement in the submarine’s history was the development of mechanical power for these watercraft.
1863 saw the first mechanically powered submarine and used compressed air as the propulsion means for the craft. Later developments towards and into the early 1900s, diesel-electric propulsion became the powers system of choice for submarines.
In these submarines, diesel engines were run when the submarine was on the surface, giving propulsion to the craft and charging the bank of batteries that were used to run the submarine when it was submerged.
A submersible is a type of submarine that is developed for various purposes, some scientific, some commercial, and some military.
A submersible is a small submarine and can be manned or unmanned, and the size and function are what generally distinguishes them from other submarines and puts them in a class of their own. They are mostly used for research or commercial purposes, such as pipeline or oil rig work.
Small submersibles are often called MROVs, Marine Remotely Operated Vehicles, or ROVs, Remotely Operated Vehicles. Some of these vehicles may be tethered to the main ship on the surface by the control cables, which carry the signals from the operator to the craft below.
On others, the submersible is not tethered to the main ship and is controlled remotely via radio signals. The unmanned submersibles are generally used for scientific research, repairs to undersea structures such as pipelines and oil rigs.
Manned submersibles generally only have the capacity to carry a limited crew, sometimes only 1 person, but in other circumstances, 3 or 4 people. These submersibles are also usually for research and exploration of the ocean depths.
Submersibles differ from submarines in that they are generally not autonomous and need a support vessel for their operation.
4. Air-Independent Propulsion Submarines
Air-independent propulsion or AIP submarines are vessels where alternative methods are used to provide oxygen to engines that normally required air for combustion. These submarines are typically non-nuclear submarines, usually powered by diesel or other types of combustion engines.
Initially, the search was done for a fuel that could burn anaerobically, but the research was then changed to find a means to provide oxygen to combustion-style engines.
There are several types of AIP submarines.
Open-cycle system submarines. Experiments with hydrogen peroxide as the method of providing oxygen to the engine were undertaken. The principle worked, but the fuel consumption was not practical. Steam turbine engines were the main type of engine that these experiments were done on.
Closed-cycle diesel engine submarines. These were diesel-powered submarines, and the oxidant for the engine was supplied in the form of liquid oxygen. The oxygen was diluted with exhaust gas from the engine to prevent the metal in the engine from melting from the excessive heat produced when pure oxygen burns.
Closed-cycle steam turbine submarines. This was a method tried by the French where steam was used for propulsion, and it was heated by burning an ethanol/oxygen mix fuel, but the energy efficiency was not as expected, resulting in the method being dropped.
Stirling-cycle engine submarines. These were built by the Swedish and combined the burning of liquid oxygen and diesel to drive generators that produced propulsion or the charging of batteries for powering an electric motor.
Fuel Cell Submarines. These are chemical reaction powered vessels and harness the power generated in chemical reactions to power the engines. Typically, this was in the form of liquid oxygen and hydrogen stored in pressurized tanks in the vessel.
5. Nuclear Submarines
The concept of nuclear-powered submarines was first conceived in 1939 by the United States Navy, and in 1951, the first nuclear-powered submarine was built.
A nuclear submarine is a vessel that is powered by a nuclear reactor on board the submarine. They have several advantages over conventional submarines in that they are oxygen-independent, so the sub only needs t surface to take on more supplies for the crew.
The long-lasting fuel and enhanced speed extend the range of these submarines almost indefinitely. Modern nuclear submarines are designed to never need refueling in their expected 25-year lifespan.
Nuclear energy is used in one of two ways to power these submarines. The nuclear reactor is used to generate electricity, which powers the submarine, or it is used to heat water to produce steam, and the steam is used to propel the submarine.
The nuclear reactor is also used to power all the other systems in the submarine, including life support systems, producing drinking water from saltwater, air purification, and the electricity needed for all the operational systems for the submarine.
There are some disadvantages to using nuclear power from a military perspective. Stealth is a problem for nuclear submarines because of a number of factors.
The heat generated by the reactor leaves a thermal signature in the water, which is visible with thermal imaging.
The reactor can never be turned off for silent running, creating steam noise that sonar can pick up.
Pumps used to circulate coolant in the reactor cannot be turned off, creating noise which also creates a sonar profile for the submarine.
Many countries spend a large portion of their military budget improving stealth properties on their nuclear submarines.
6. Tourist Submarines
Many companies create and operate submarines as part of the entertainment that they offer at various facilities. This experience gives the general public the opportunity to experience underwater wildlife and scenery.
Tourist submarines are made to display underwater life at tourist attractions and typically do not go deeper than normal scuba diving depths of 100 to 120-feet. The capacity of these submarines is generally between 50 to 100 people. These submarines are owned and operated privately.
An example of a tourist submarine is the Windermere, operating in a lake in Cumbria in England, transporting tourists to view a wreck and also some trips further afield in the lake.
Submarines are not only the realm of scientific research, commercial undertakings, or the military. Recent developments have seen criminals using submarines for drug smuggling.
Narco-submarines are submarines or semi-submarines that are used to transport illegal drugs undetected. This type of drug trafficking is done by South American drug smugglers transporting their drugs to the USA coastal waters. Large quantities of narcotics can be smuggled this way.
Semi-submarines are craft that travel partially submerged, but a part of the vessel remains above water all the time. Drug cartels have used both semi-submarines and full submarines in this nefarious enterprise in an effort to thwart detection by South American and the United States law enforcement.
8. Deep Diving Submarines
Extreme depths are challenging even for the sophisticated submarines of the military. The crushing power of the water at great depth limits the depth to which these behemoths can go. At these depths, smaller is better to create a vehicle that can withstand the external pressure.
Deep diving submarines are vessels that have been developed for scientific exploration of the extreme depths of the deepest parts of our oceans. The submarines are usually small and compact and only have space for a crew of one or two people. These vessels are usually run by research institutes.
Deep diving submersibles will usually have robotic arms for taking samples at depth, a large number of lights for operating in the dark depths, and recording equipment to capture photographs and video of the deep sea life and environment.
9. Military Submarines
Submarines are key strategic vessels for any country that has a large coastline to protect and which has a large naval force.
A military submarine is any submersible vessel that is used for military applications to defend a nation against attack from an aggressor and protection of the nation’s borders. Military submarines come in a variety of classes, depending on their energy source, capabilities, and intended purpose.
Over 46 countries maintain submarines as active vessels in their respective navies. The majority of these are non-nuclear submarines. Only six nations currently operate nuclear submarines as a part of their fleet; the USA, UK, Russia, France, China, and India.
10. U-Boat Submarines
U-boat is a term that you will often hear in reference to submarines used in the World War I period and World War II era, but it was not used for all submarines.
U-boat is a term that was used to refer to German submarines, which was derived from their German name, which means under-sea-boat. Germany used submarines to great effect in World War II to create blockades to prevent supply ships from resupplying their enemy troops.
Even though these submarines had some success against enemy warships, their primary role was to hunt the merchant fleets from the USA, Canada, and Britain. The U-boats often hunted these fleets in packs, termed wolf-packs, and were very effective in this role until allies developed several effective countermeasures.
Radar enhancements, high-frequency direction finding, sonar, depth charges, and anti-submarine mortars, and cracking of the German Enigma code all contributed to defeating the U-boat attacks on the merchant convoys.
11. Fast Attack Submarines
Fast attack submarines are a class of military submarines that are designed with mostly one purpose. They are often also called hunter-killer submarines which gives a clue as to their purpose.
Fast attack submarines or hunter-killer submarines are designed for hunting and destroying other submarines and warships. They do not usually have vertical launch capability but rather torpedo weapons for sinking enemy submarines and ships. They can be nuclear or diesel-electric powered vessels.
Some attack submarines are fitted with cruise missile capability to increase their versatility in several roles. Attack submarines are usually deployed to protect ballistic missile submarines or fleets of surface warships from attack by enemy warships and submarines.
They are normally smaller and sleeker than submarines designed for vertical missile launch capability and carry very sophisticated detection equipment.
12. Ballistic Missile Submarines
The most diverse types of submarines are the ones that have been developed for different purposes in the military.
Ballistic missile submarines are submarines that have been developed with vertical launch capability of ballistic missiles and cruise missiles, often with nuclear warheads. This gave the submarine the capability of long-distance strikes against both land and sea-based targets.
This development made the submarine a completely different strategic weapon for the military. The stealth ability of this craft allows them to hide anywhere and launch long-range attacks from almost anywhere on the globe.
13. Midget Submarines
As expected, midget submarines are son named due to their diminutive size. Most of the early submarines can be considered to be in this class, as they were not large vessels.
Midget submarines are any submarine that is under 150 tons and can be operated by a crew of a few as 2 or up to 9 crew. They can be for military use, where they are used for shallow harbor invasion or civilian purposes for exploration, underwater repairs, and underwater scientific research.
These small vessels usually have no sleeping or food preparation facilities and are designed for short missions. Military versions were often used as a means of delivering combat divers close to their targets and for extraction of these divers after the mission.
Exploration of the depths of the sea often requires taking divers to these dangerous depths where they can operate from a position of relative safety. The bathysphere was developed for this purpose.
A bathysphere is a non-powered, spherical submersible that is used to lower and retrieve divers from great depths and allow divers to explore and study the deep-sea environment. The craft is lowered to depth via a steel cable that is secured to a ship on the surface.
The bathysphere operates as a base at depth for the divers to make excursions out into the water and return to the vehicle to rest. The divers in the vehicle will undergo decompression as they are raised to the surface to prevent decompression sickness or the bends, which can be a fatal consequence of breathing compressed air at depth.
Normal submarines cannot get to the deepest parts of the ocean because the pressure at these depths would crush the hull of normal submarines. Specialized craft are needed for this type of exploration.
A bathyscaphe is similar to a bathysphere, but it is a self-propelled submersible that contains a crew cabin but is suspended beneath a float rather than from a cable on a ship. It was invented by a Swiss inventor and explorer, Auguste Piccard, for ocean exploration.
A vehicle of this type carried Jacques Piccard, the son of Auguste Piccard, and Don Walsh to the deepest known part of our ocean, the Challenger Deep in the Mariana Trench. The record depth was over 35000-feet or 10Km deep, where they discovered aquatic life living in the absence of light and in the enormous pressure of this depth.
16. Air-Sea Rescue Submarines
Submarines not only provided a stealthy means to attack the enemy but also provided important rescue missions.
Certain classes of submarines were tasked with the rescue of downed fighter pilots in the Pacific during World War II and became known as the Lifeguard League of submarines. These vessels were positioned strategically before air attacks to rescue downed pilots or pilots who had to ditch their aircraft.
This air-sea rescue role of submarines became one of the most important tasks that submarines performed in the Pacific seas during World War II.
17. Single Hull Submarines
The designs of submarines have changed over the centuries, and as we began to understand the effects of pressure from the water on the hull, particularly at greater depths.
A single hull submarine is a vessel that has a single pressure hull that is designed to protect the crew from the dangers of the high pressure of the surrounding water at depth. The best shape for a pressure hull is a cylindrical shape which is not the best shape for speed underwater.
The early versions of submarines and even many modern submarines and submersibles have a single pressure hull, but larger submarines, especially military vessels, needed speed, which the design of the single-hull did not provide for.
18. Double Hull Submarines
Engineers and submarine builders soon realized that the best shape hull to provide pressure protection was not the best shape for the submarine to glide through the water with minimal resistance and speed.
Double hull submarines were developed to have an inner pressure hull which provided the crew with protection from the pressure, and an outer non-pressure hull which provided the best shape for the submarine to cut through the water with less resistance increasing speed and efficiency.
The outer hull of a double-hull submarine is not pressurized and is at the same pressure as the surrounding water, which does not require the outer hull to have much structural strength for pressure resistance.
The inner hull, which was encased with the outer hull, was engineered to be thicker and stronger to withstand the extreme pressures of the depths of the oceans.
A breach of the outer hull is therefore not an event that will cause the sinking of the sub or any danger to the crew contained behind the pressure hull or inner hull.
19. Personal Submarines
Technology, materials, and safety have improved to the point that many companies are manufacturing submarines and submersibles for the general public, making the submarine no longer the exclusive realm of science and the military.
Personal submarines are recreational submarines that are made for pleasure and are often made as a partner vessel for luxury yachts. They are normally one or two-person submarines with limited depth capability and intend for enjoying the undersea landscape, usually on shallow coral reefs.
Personal submarines usually serve no other purpose than recreation, and as such, they are not equipped with robotics or sensitive devices for telemetry or information gathering.
Exploration of the unknown and the quest for knowledge is a trait of mankind that drives us to extend our reach to the most remote and dangerous places of the world and the universe that we live in.
Submarines have enabled us to explore the depths of the oceans, and as the technology of these vessels improves, we will be able to reach these deep regions of our planet with more ease.
Many see submarines as only a weapon of war, and while they have been used for this purpose, they also offer us a vehicle for moving forward with the exploration of our oceans and our pursuit of knowledge of the depths and what inhabits them.
Image Source: US Navy