Sea mines are explosive charges that are used in the water against ships and submarines. The generic term for the material used in mine warfare is “barrage weapons”.
The aim of the invention of the sea mine was to destroy enemy warships by fire or detonation. Such a weapon is particularly interesting for those warring parties who cannot oppose an opposing navy with a fleet that is equal in surface combat. In terms of Mahan's sea power theory, the sea mine is a typical means of “sea denial”. You can use it to deny an opponent the use of sea areas, but you cannot establish your own superiority.
Forerunner of the sea mines were the Brander , set fire to ships that are in an enemy fleet was in drive to the wooden warships to light. The first explosive charge that was brought to its destination underwater was designed by David Bushnell in 1776 during the American Revolutionary War . It was equipped with a time fuse and was attached to enemy ships with a hook.
Two types of naval weapons developed from such underwater charges in the 19th century: the stationary sea mine and the movable torpedo .
The American Samuel Colt developed a functioning electrically remote-controlled mine in 1842, but the project was stopped. The well-known inventor and industrialist Werner von Siemens , together with the chemist August Friedrich Karl Himly, constructed sea mines for the defense of the port of Kiel in 1848 during the Schleswig-Holstein War , which could be ignited electrically from land. In the American Civil War , underwater charges were also used, which, like Bushnell, were brought to their destination underwater and detonated there.
Despite these developments, the mine played only a minor role in the naval wars of the 19th century. It was not until the world wars that large numbers of mines were used, which had a significant influence on the movements of the naval forces and tied up strong forces. Mine plans also played an important role during the Cold War . During this period, sea mines were used primarily in the Vietnam War , the First Gulf War and in the mining of Nicaraguan ports in the Contra War . After the end of the Cold War, the use of mines lost its importance in the planning of the naval forces.
Sea mines are readily available to many navies, available in very different designs, inexpensive, of simple technology and at the same time a serious threat even for a technologically superior attacker. They are very effective weapons in terms of cost-effectiveness. The frigate USS Samuel B. Roberts (FFG-58) , for example, was put out of action by an Iran-launched M-08 contact mine from Soviet production valued at only US $ 1,500, while its repair cost US $ 135 million.
Sea mines can be divided into ground mines and anchor mines according to their positioning and into touch and remote ignition mines according to the type of detonator. Most of these conventional mines can be laid in water up to 60 m.
Anchor mines are simple weapons, essentially based on mechanics, which can also be manufactured and used inexpensively by technologically not very developed countries. Ground mines are technically more demanding and more difficult to clear than anchor mines.
In addition to this classification, there are a number of specialty mines.
A floating mine is a floating sea mine equipped with contact fuses. Because their movements cannot be predicted over a longer period of time, their use is only promising if predictable currents drive the mines into their target area. Because of the dangers posed by floating mines to shipping, international law requires that mines without ground contact must be disarmed one hour after being released.
Anchorage mines consist of a mine cart or anchor that sinks to the seabed and the mine vessel, which is attached to the mine cart with a wire rope, the so-called anchor rope, and which, due to its buoyancy, floats close to the surface of the sea. Anchor mines are usually equipped with touch fuses and are triggered by contact with a ship's hull. At greater depths, anchor mines are also used against submarines .
The anchor mine is the oldest type of mine used in large numbers. The first were deployed in front of the Hudson and Richmond forts as early as 1813. The mine barriers of the First World War consisted exclusively of anchor mines , those of the Second World War predominantly, and anchor mines were also planned or used in the Cold War and in regional conflicts after 1945.
The correct depth setting is important for anchor mines. If the mine is too deep, ships can pass it undamaged. If, on the other hand, it is too flat, there is a risk that the mine vessel is visible on the surface and thus reveals the lock. With the first mine barriers, the exact water depth had to be plumbed before laying and then the corresponding anchor rope length had to be set. This lengthy method was suitable for blocking in one's own waters, but not for blocking enemy ports.
In the Russo-Japanese War , mines were used that anchored themselves to a depth set before throwing. Initially, two different systems for automatic depth adjustment were used. When setting by water pressure, the mine vessel with the anchor sinks to the bottom. The vessel then detaches from the anchor and rises until the ambient pressure has decreased to such an extent that a spring device clamps the anchor rope. This system was used by the Imperial Navy until 1918. A double anchor rope was required, which resulted in the mine undercut in the current due to the increased water resistance and the mine being up to several meters too deep. With the lead anchor, the required depth is set using the lead . After throwing the mine vessel remains on the surface for the time being, while the anchor with the lead weight sinks. When the lead weight, which sinks faster than the anchor, reaches the bottom, a brake blocks the anchor rope and the mine vessel is pulled to the set depth. From 1916, the Royal Navy introduced the closed leading anchor, which is simpler and more reliable. Here the air-filled anchor box connected to the mine vessel floats on the surface until the lead weight has reached the set distance. Now the mine vessel detaches from the anchor, which now overflows and sinks to the bottom. During the Second World War , this was the most frequently used method of anchoring by all participating states.
Ground mines lying on the sea floor were developed as early as the First World War. Ground mines are remote ignition mines that respond to ships passing in the immediate vicinity. The destructive effect is based on the gas and foam bubble created during the detonation, which initially lifts the hull. When the gas bubble breaks through the surface of the water and loses its pressure, a hollow space is created under the ship for a short time and the load-bearing effect of the water in this area ceases to exist. The affected area is first raised in a shock, then dropped again, which leads to severe personnel losses and damage to the hull. Often the hull breaks apart, which means the total loss of the ship.
Contact detonators are based on chemical, mechanical or electrical principles. The chemical principle is mostly based on the violent reaction of two substances. Mechanical triggering takes place via a shock-sensitive initial explosive .
Conventional touch ignition systems consist of an electrical ignition mechanism and several touch sensors in the form of so-called ignition horns. These horns consist of a tube protruding from the outside of the mine vessel, in which there is a glass tube filled with acid. If the tube is bent by violent contact, the glass tube breaks and the acid flows into a dry galvanic element , which in turn generates the current for the ignition mechanism. This ignition system has the advantage that it remains operational for an extremely long time. Contact ignition systems in which the ignition horns only represent contacts and the ignition energy is made available by a built-in battery are dependent on the capacity of the battery and tend to lose their operational readiness.
Remote ignition mines usually respond (even if they are unsupervised) to changes in their immediate surroundings, i.e. the surrounding magnetic field , noise or water pressure . When a ship moves over a mine, all three environmental values change. The first ground mines responded only to the magnetic field, newer ones also to one of the other or more of these values. Some detonators are provided with a delay so that the mine does not trigger under the bow. Mines can also be equipped with counters, which respond only after a certain number of overflows, in order to make it difficult to locate a minefield and to clear it. Modern sea mines have a combination of several sensors and can detect certain ship sizes or even their types.
Special mines have been developed for special tasks, for example for use in great water depths or against submarines. Anchor mine mines with remote ignition have been developed, which are laid in great water depths and whose mine vessels float at similar depths to which ground mines are otherwise laid. This makes it possible to mine very deep waters.
The special mines also include those that can be switched on and off or even ignited from land. Such mines are used to protect own port entrances and waterways.
Anti-invasion mines (also known as river or shore mines) can be laid off coasts where enemy landings are expected. These ground mines are particularly suitable for use in very shallow water, are in part similar to land mines and can also detect small landing craft and hovercraft with their magnetic, electromagnetic or sound sensors . Their load is usually small, but sufficient for the intended purpose. Several such types of mines have been developed, especially in the Soviet Union. In some cases, suitable sea mines are also used for shallow waters, such as the German Sea Mine Antiinvasion (SAI) DM 51 or the US NAVAL MINE, MK 62 MOD 0 QUICKSTRIKE, which is dropped from aircraft.
Another special form are combinations of mines and torpedoes. Torpedomines like the American MK-60 CAPTOR are weapon systems that consist of a platform and a torpedo. When a ship or submarine approaches, the torpedo is launched and attacks its target in a self-seeking manner. Another variant are torpedoes, which remain as a base mine after a few nautical miles of running. In this way, mines can be brought into waters that the mine carrier himself cannot navigate because they are dominated by the enemy or, such as estuaries, are too shallow. An example of this type is the American MK-67, which consists of a modified MK-37 torpedo with additional ignition devices and can be fired by submarines.
The use of mines is based on various military considerations and is subject to restrictions under international law .
International law provisions
The most important provisions on the use of sea mines can be found in the VIII Hague Agreement , the "Agreement on the Laying of Submarine Automatic Contact Mines" of 1907.
After that, floating contact mines ( drift mines ) must be disarmed one hour after exposure. Anchor tow mines must be blurred if they tear themselves out of their anchoring. Torpedoes need to be disarmed if they miss their target. These regulations are intended to prevent sharp explosive charges from endangering the seas in an uncontrolled manner and without further military benefit.
After the end of the war, each party is required to clear the mines off their coasts and to inform the other party of the barriers it has placed in their waters.
Shipment of the mines
Mines can be moved by ships, submarines and aircraft. Mine- layers can lay mines in large numbers and are mostly used to throw large-scale mine barriers. Merchant ships with large continuous deck areas (such as ferries or RoRo freighters ) can be fitted with mine rails within a few hours and used as auxiliary mine layers. Many warships have at least limited mine-laying capacity. Submarines can usually only carry a small number of mines, but can also lay them unnoticed in waters dominated by the enemy.
Military considerations when using mines
A basic distinction is made between offensive and defensive mining operations . A mine operation in the waters of an opponent or on the sea routes used by him is referred to as offensive. Offensive mine barriers are designed to prevent the enemy from leaving their ports or to force them to choose sea routes that are easier to attack. So it can be the job of a mine barrier to block a sea route along the coast and force enemy ships into deep water, where submarines can be used against them.
When it comes to defensive mining, a distinction is made between defensive and protective mine-laying . Defensive minefields are placed under their own control in international waters. They serve to steer shipping in their own interest and to protect their own sea routes. Protective mine barriers are placed in their own territorial waters to defend coastlines, roads and ports. In the case of protective and defensive barriers off the own coast, covered passages are usually left in place for the own shipping traffic. These can be additionally secured by controlled mines.
Terrorist mine operation
Since mines are easy to produce and can be laid easily and unobserved by merchant ships, they are suitable for acts of terrorism against sea routes. The largest known case was the mining of the Red Sea in the summer of 1984. An unknown merchant ship had laid a large number of mines - according to letters of confession 190 - which damaged a number of ships. Almost 30 anti-mine vehicles from seven countries searched from August to November 1984, and a mine was found and recovered. It was a Soviet product, the charge of which was so reduced that it was supposed to lead to damage, but not to sink. In order not to affect shipping through the Suez Canal , Egypt in particular tried to downplay the incident. Other states shared this effort out of concern for maritime trade .
The mine hazard can be countered by avoiding or removing the mines.
Ships can be protected from mines by a number of technical and organizational measures. While one will usually forego technical mine protection on merchant ships in peacetime, some very elaborate protective measures can be found on warships. Many warships have a mine own protection system against magnetic mines. This system consists of large electrical loops built into the ship. They generate a magnetic field that compensates for the ship's own magnetic field and thus prevents the disturbance of the earth's magnetic field, which can lead to the ignition of magnetic mines. The “demagnetization” of the ships in special systems is less complex. However, the effect is less and only temporary, so that the process has to be repeated regularly.
Anti-mine vehicles , i.e. minesweepers, clearing boats and mine hunting boats, are also protected against mines. They have a shallow draft so as not to ignite any anchor mines, and their magnetic and acoustic signatures are extensively attenuated. These vehicles are usually made of non-magnetizable materials such as wood, plastic or special steel. Many minesweepers also have a mine avoidance sonar , with the help of which they can detect and avoid anchor mines on their course.
In order to protect shipping in the event of a mine hazard, mine-free routes are being created through which ships are guided. If there is a high mine hazard, the ships are guided outside these routes by anti-mine vehicles driving ahead. For almost thirty years after the Second World War, so-called compulsory routes existed in the North and Baltic Seas, on which merchant shipping was dependent. When leaving the path, the insurance cover expired .
Search and clear
The most important methods of mine clearance are differentiated between mine clearing and mine hunting . The warships used for this purpose are summarized under the generic term anti-mine vehicles .
Mine clearing involves various methods with the help of which mines in a search area are to be rendered harmless using technical means.
To clear anchor mines, clearing harnesses are used, which are pulled through the water by minesweepers. They are either used by several boats in a group or by individual boats whose clearing cables are controlled laterally with the help of otter boards. With the help of floats, the cables are guided to a predetermined clearing depth and are supposed to grasp and cut the anchor ropes of the mines with attached grippers. The mine vessels then float up and are detonated with firearms.
Ground mines are cleared with simulated signatures to which the detonators of the mines respond. So-called hollow rods, which are towed by minesweepers, contain a large magnetic coil and simulate the magnetic fields of larger ships. Sound buoys that are also towed can simulate the sound fields of ships. The German Troika system uses self-propelled remote-controlled hollow rods that also carry a noise buoy. Such a system enables mine search with little risk to personnel.
Magnetic fields can also be simulated by airplanes and especially by helicopters with magnetic coils. As early as the Second World War, the Wehrmacht used Junkers Ju 52 / 3m aircraft ( MAUSI variant ) with a large magnetic coil to clear mines. The US Navy uses Sikorsky S-65 helicopters in the RH-53A variant, which pull a clearing slide across the surface of the water.
In contrast to magnetic and noise fields, pressure fields cannot be simulated. Mines with pressure detonators can only be cleared with barrier breakers , which, as specially protected ships, overflow the mines and detonate them.
During mine hunting, individual mines are located with the help of high-resolution sonar devices . They can then either be defused or specifically blown up. Mine divers or remote-controlled underwater drones can be used to identify the mines and destroy them . One example of this is the German Navy's "Pinguin" mine-hunting drone . It usually has a camera system and, depending on the equipment, a short-range sonar and can drop up to two remotely detonable mine destruction charges or attach them to the anchor rope in order to destroy mines. If a mine is to be defused and recovered for the analysis of the minefield, mine divers are required. The class 332 mine hunters were specially developed for these tasks. They originally had an extendable and swiveling sonar dome, two “Penguin” mine-hunting drones and all the equipment for mine divers, including a diver pressure chamber and bottle filling station.
In contrast to classic mine clearance, mine hunting is very time-consuming, but all located mines can be destroyed. Since the sonar systems used for mine hunting must be particularly sensitive and the sonar location is based on sound waves, attempts are made to avoid any interference. Therefore, modern mine hunters also use a particularly quiet drive and only travel at low speed. Otherwise, extreme noise discipline must be observed. Mine hunting was also developed in order to be able to bring ship formations safely through possible mine areas. So you could have found a mine-free passage through a mine area with a mine hunter.
However, mine hunting techniques also allow other applications. Mine hunting boats were used to investigate the condition of the seabed over a large area in new naval training areas after German reunification. In some cases, old ammunition was discovered, which could then be recovered and safely destroyed. Sunken ships and other wreckage could also be located if their exact position was not known. So the new technology also had civilian uses.
Mine repellants and modern mines
Mine use and mine defense are subject to a constant technical race. One tries to make mines resistant to defensive measures in a variety of ways. One of the oldest measures was to apply so-called minefield protection agents, mine-like floating bodies, which are supposed to destroy the clearing wires, in fields of anchor towers. In some cases, special mines are used against clearing by mine divers, which are supposed to ignite when a diver comes near them. Modern ground mines are constructed in such a way that they change their surface to camouflage and quickly overgrow with seaweed or dig themselves completely into the ground and can therefore hardly be located with mine-hunting equipment.
Mine clearance and mine hunting complement each other in mine defense. While the deminers can work faster and clear mines that a mine hunter might have overlooked (e.g. mines hidden in the sand and overgrown), mine hunting can also be used to find mines that are resistant to most clearance methods (e.g. mines). B. with pressure detonators or "intelligent detonators"). One of the trends in mine defense is the use of remote-controlled systems to reduce the risk to personnel. In addition, such systems can also be used by many other vehicles which, for example due to their often small size and speed, are only suitable to a limited extent for remote operations. In coastal waters, it could even be operated from land.
There have also been attempts with dolphins to track down mines and to bring destruction charges to the mines found. However, modern mine-hunting drones promise more reliable success with less effort. In addition, drones as technical devices can be replaced quickly and equally, while good training usually takes a longer time.
Effects of Mine Warfare
To this day, many seas, mostly in the coastal regions, are polluted by mines from both world wars . This is especially true for the Baltic and North Seas . By 1972 sea routes in the North and Baltic Seas were systematically cleared of sea mines and marked as mine-free on sea charts . Due to the age of their technical equipment such as detonators and batteries and the corrosion from the influence of seawater, the risk from the remaining mines was not classified as higher than the risk from seafaring at all.
Nevertheless, mines from the time of the Second World War in the Baltic Sea are still being cleared by the neighboring countries. In May 2013, for example, twelve British ground mines were discovered in the Kiel Fjord , and until they were cleared, shipping traffic had to be diverted onto the Kiel-Baltic Sea route. In order to destroy the remaining World War II mines, a joint exercise of most of the Baltic Sea navies takes place every year under the direction of the German Navy under the name " Open Spirit ", during which over 400 mines and underwater explosive devices have been cleared since 1996.
- Mine Force Flotilla
- International Mine Clearance Board
- Magneto (weapon)
- Mine Countermeasure Vessels Operational Sea Training
- Operation south flank
- Evacuation guide
- Underwater weapon
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