Naval mine

U.S. Navy, Washington, District of Columbia. 3M likes. We are the United States Navy, our Nation's sea power - ready guardians of peace, victorious in war.

Many of the boats that sailed to Dunkirk were degaussed in a marathon four-day effort by degaussing stations. These latter three mines are actually a single type of electronic fuze fitted to Mk82 , Mk83 and Mk84 air-dropped bombs.

A moving and fantastic discovery of a letter by Galileo lost for years. In this letter, written by Galileo in , he set out for the first time his arguments that scientific .
A naval mine is a self-contained explosive device placed in water to damage or destroy surface ships or submarines. Unlike depth charges, mines are deposited and left to wait until they are triggered by the approach of, or contact with, any vessel.
Naval Academy Midshipmen flew with the U.S. Air Force 53rd WRS
U.S. Navy, Washington, District of Columbia. 3M likes. We are the United States Navy, our Nation's sea power - ready guardians of peace, victorious in war.
A moving and fantastic discovery of a letter by Galileo lost for years. In this letter, written by Galileo in , he set out for the first time his arguments that scientific .

Naval Academy Midshipmen flew with the U.S. Air Force 53rd WRS

Wu, Smithsonian , "Operation Calamari: How the Smithsonian Got Its Giant Squids," 21 June The heir presumptive was just 13 at the time — five years younger than the naval cadet — but quickly fell in love. First Known Use of naval 15th century, in the meaning defined at sense 1. History and Etymology for naval Middle English, from Latin navalis , from navis ship.

Learn More about naval. Resources for naval Time Traveler! Explore the year a word first appeared. Dictionary Entries near naval Navajo blanket Navajo National Monument Navajo stitch naval naval architect naval attaché naval auxiliary. Time Traveler for naval The first known use of naval was in the 15th century See more words from the same century. More Definitions for naval. English Language Learners Definition of naval.

Kids Definition of naval. More from Merriam-Webster on naval Spanish Central: Translation of naval Nglish: Translation of naval for Spanish Speakers Britannica English: Therefore, many countries demand that all mining operations be planned on land and records kept so that the mines can later be recovered more easily. In some cases, mines are automatically activated upon contact with the water. In others, a safety lanyard is pulled one end attached to the rail of a ship, aircraft or torpedo tube which starts an automatic timer countdown before the arming process is complete.

Typically, the automatic safety-arming process takes some minutes to complete. This allows the people laying the mines sufficient time to move out of its activation and blast zones. In the s, Germany had experimented with the laying of mines by aircraft.

It became a crucial element in their overall mining strategy. Aircraft had the advantage of speed, and they would never get caught in their own minefields.

From April to June , the Luftwaffe laid 1, mines in British waters. Soviet ports were mined, as was the Arctic convoy route to Murmansk. A very large chemical mine was designed to sink through ice with the aid of a melting compound. In September , the UK announced the placement of extensive defensive minefields in waters surrounding the Home Islands. Offensive aerial mining operations began in April when 38 mines were laid at each of these locations: In the next 20 months, mines delivered by aircraft sank or damaged Axis ships with the loss of 94 aircraft.

By comparison, direct aerial attacks on Axis shipping had sunk or damaged vessels at a cost of aircraft lost. The advantage of aerial mining became clear, and the UK prepared for it. The United States' early aerial mining efforts used smaller aircraft unable to carry many mines.

Using Grumman TBF Avenger torpedo bombers, the US Navy mounted a direct aerial mining attack on enemy shipping in Palau on 30 March in concert with simultaneous conventional bombing and strafing attacks.

The dropping of 78 mines stopped 32 Japanese ships from escaping Koror harbor; the combined operation sank or damaged 36 ships. First, aerial mines would have to be developed further and manufactured in large numbers. Second, laying the mines would require a sizable air group. The US Navy lacked suitable aircraft. Johnson set about convincing General Curtis LeMay of the efficacy of heavy bombers laying aerial mines. Both British and American mines were used.

Japanese merchant shipping suffered tremendous losses, while Japanese mine sweeping forces were spread too thin attending to far-flung ports and extensive coastlines. Kinkaid , who directed nearly all RAAF mining operations in CBI, heartily endorsed aerial mining, writing in July that "aerial mining operations were of the order of times as destructive to the enemy as an equal number of bombing missions against land targets.

Prince Fumimaro Konoe said after the war that the aerial mining by Bs had been "equally as effective as the B attacks on Japanese industry at the closing stages of the war when all food supplies and critical material were prevented from reaching the Japanese home islands.

Survey analysts projected that this would have starved Japan, forcing an earlier end to the war. Johnson looked at the Japan inner zone shipping results, comparing the total economic cost of submarine-delivered mines versus air-dropped mines and found that, though 1 in 12 submarine mines connected with the enemy as opposed to 1 in 21 for aircraft mines, the aerial mining operation was about ten times less expensive per enemy ton sunk.

Between , and 1,, naval mines of all types were laid in WWII. Advancing military forces worked to clear mines from newly-taken areas, but extensive minefields remained in place after the war. Air-dropped mines had an additional problem for mine sweeping operations: In Japan, much of the B mine-laying work had been performed at high altitude, with the drifting on the wind of mines carried by parachute adding a randomizing factor to their placement.

Generalized danger areas were identified, with only the quantity of mines given in detail. Mines used in Operation Starvation were supposed to be self-sterilizing, but the circuit did not always work.

Clearing the mines from Japanese waters took so many years that the task was eventually given to the Japan Maritime Self-Defense Force.

For the purpose of clearing all types of naval mines, the Royal Navy employed German crews and minesweepers from June to January , [66] organised in the German Mine Sweeping Administration GMSA , which consisted of 27, members of the former Kriegsmarine and vessels.

Two such examples were the liberty ships Pierre Gibault which was scrapped after hitting a mine in a previously cleared area off the Greek island of Kythira in June , [68] and Nathaniel Bacon which hit a minefield off Civitavecchia , Italy in December , caught fire, was beached, and broke in two. The damage that may be caused by a mine depends on the " shock factor value", a combination of the initial strength of the explosion and of the distance between the target and the detonation.

Usually only created by contact mines, direct damage is a hole blown in the ship. Among the crew, fragmentation wounds are the most common form of damage. Flooding typically occurs in one or two main watertight compartments, which can sink smaller ships or disable larger ones. Roberts mine attack being a good example of a contact mine detonating amidships and underneath the ship. The bubble jet effect occurs when a mine or torpedo detonates in the water a short distance away from the targeted ship.

The explosion creates a bubble in the water, and due to the difference in pressure, the bubble will collapse from the bottom. The bubble is buoyant, and so it rises towards the surface. If the bubble reaches the surface as it collapses, it can create a pillar of water that can go over a hundred meters into the air a "columnar plume". If conditions are right and the bubble collapses onto the ship's hull, the damage to the ship can be extremely serious; the collapsing bubble forms a high-energy jet that can break a metre-wide hole straight through the ship, flooding one or more compartments, and is capable of breaking smaller ships apart.

The crew in the areas hit by the pillar are usually killed instantly. Other damage is usually limited. The Baengnyeong incident , in which the ROKS Cheonan broke in half and sank off the coast South Korea in , was caused by the bubble jet effect, according to an international investigation.

If the mine detonates at a distance from the ship, the change in water pressure causes the ship to resonate. This is frequently the most deadly type of explosion, if it is strong enough. Engines rip from their beds, cables from their holders, etc. A badly shaken ship usually sinks quickly, with hundreds, or even thousands [ example needed ] of small leaks all over the ship and no way to power the pumps. The crew fare no better, as the violent shaking tosses them around.

The resulting gas cavitation and shock-front -differential over the width of the human body is sufficient to stun or kill divers. Weapons are frequently a few steps ahead of countermeasures, and mines are no exception. In this field the British, with their large seagoing navy, have had the bulk of world experience, and most anti-mine developments, such as degaussing and the double-L sweep, were British inventions. When on operational missions, such as the recent invasion of Iraq, the US still relies on British and Canadian minesweeping services.

The US has worked on some innovative mine-hunting countermeasures, such as the use of military dolphins to detect and flag mines.

However, they are of questionable effectiveness. They are small and as technology has developed they can have anechoic coatings, be non-metallic, and oddly shaped to resist detection.

Ships can be designed to be difficult for mines to detect, to avoid detonating them. This is especially true for minesweepers and mine hunters that work in minefields, where a minimal signature outweighs the need for armour and speed. These ships have hulls of glass fibre or wood instead of steel to avoid magnetic signatures.

These ships may use special propulsion systems, with low magnetic electric motors , to reduce magnetic signature, and Voith-Schneider propellers, to limit the acoustic signature. They are built with hulls that produce a minimal pressure signature. These measures create other problems. They are expensive, slow, and vulnerable to enemy fire. Many modern ships have a mine-warning sonar —a simple sonar looking forward and warning the crew if it detects possible mines ahead.

It is only effective when the ship is moving slowly. A steel-hulled ship can be degaussed more correctly, de-oerstedted or depermed using a special degaussing station that contains many large coils and induces a magnetic field in the hull with alternating current to demagnetize the hull. This is a rather problematic solution, as magnetic compasses need recalibration and all metal objects must be kept in exactly the same place. Ships slowly regain their magnetic field as they travel through the Earth's magnetic field, so the process has to be repeated every six months.

A simpler variation of this technique, called wiping , was developed by Charles F. Goodeve which saved time and resources. Three kinds of steel were used in shipbuilding: The models were placed within coils which could simulate the Earth's magnetic field at any location.

The magnetic signatures were measured with degaussing coils. The objective was to reduce the vertical component of the combination of the Earth's field and the ship's field at the usual depth of German mines. From the measurements, coils were placed and coil currents determined to minimize the chance of detonation for any ship at any heading at any latitude.

Some ships are built with magnetic inductors , large coils placed along the ship to counter the ship's magnetic field. Using magnetic probes in strategic parts of the ship, the strength of the current in the coils can be adjusted to minimize the total magnetic field. This is a heavy and clumsy solution, suited only to small-to-medium-sized ships. Boats typically lack the generators and space for the solution, while the amount of power needed to overcome the magnetic field of a large ship is impractical.

Active countermeasures are ways to clear a path through a minefield or remove it completely. This is one of the most important tasks of any mine warfare flotilla. A sweep is either a contact sweep, a wire dragged through the water by one or two ships to cut the mooring wire of floating mines, or a distance sweep that mimics a ship to detonate the mines. The sweeps are dragged by minesweepers , either purpose-built military ships or converted trawlers.

Each run covers between one and two hundred meters, and the ships must move slowly in a straight line, making them vulnerable to enemy fire. This was exploited by the Turkish army in the Battle of Gallipoli in , when mobile howitzer batteries prevented the British and French from clearing a way through minefields.

If a contact sweep hits a mine, the wire of the sweep rubs against the mooring wire until it is cut. Sometimes "cutters", explosive devices to cut the mine's wire, are used to lessen the strain on the sweeping wire. Mines cut free are recorded and collected for research or shot with a deck gun.

Minesweepers protect themselves with an oropesa or paravane instead of a second minesweeper. These are torpedo-shaped towed bodies, similar in shape to a Harvey Torpedo, that are streamed from the sweeping vessel thus keeping the sweep at a determined depth and position. Some large warships were routinely equipped with paravane sweeps near the bows in case they inadvertently sailed into minefields—the mine would be deflected towards the paravane by the wire instead of towards the ship by its wake.

More recently, heavy-lift helicopters have dragged minesweeping sleds, as in the Persian Gulf War. The distance sweep mimics the sound and magnetism of a ship and is pulled behind the sweeper. It has floating coils and large underwater drums. It is the only sweep effective against bottom mines. Mk I fitted with degaussing coils to trigger magnetic mines. Modern influence mines are designed to discriminate against false inputs and are, therefore, much harder to sweep.

They often contain inherent anti-sweeping mechanisms. For example, they may be programmed to respond to the unique noise of a particular ship-type, its associated magnetic signature and the typical pressure displacement of such a vessel. As a result, a mine-sweeper must accurately mimic the required target signature to trigger detonation. The task is complicated by the fact that an influence mine may have one or more of a hundred different potential target signatures programmed into it.

Another anti-sweeping mechanism is a ship-counter in the mine fuze. When enabled, this allows detonation only after the mine fuze has been triggered a pre-set number of times. To further complicate matters, influence mines may be programmed to arm themselves or disarm automatically—known as self-sterilization after a pre-set time. During the pre-set arming delay which could last days or even weeks the mine would remain dormant and ignore any target stimulus, whether genuine or false.

When influence mines are laid in an ocean minefield, they may have various combinations of fuze settings configured. For example, some mines with the acoustic sensor enabled may become active within three hours of being laid, others with the acoustic and magnetic sensors enabled may become active after two weeks but have the ship-counter mechanism set to ignore the first two trigger events, and still others in the same minefield with the magnetic and pressure sensors enabled may not become armed until three weeks have passed.

Groups of mines within this mine-field may have different target signatures which may or may not overlap. The fuzes on influence mines allow many different permutations, which complicates the clearance process. Mines with ship-counters, arming delays and highly specific target signatures in mine fuzes can falsely convince a belligerent that a particular area is clear of mines or has been swept effectively because a succession of vessels have already passed through safely.

As naval mines have become more sophisticated, and able to discriminate between targets, so they have become more difficult to deal with by conventional sweeping. This has given rise to the practice of mine-hunting.

Mine hunting is very different from sweeping, although some minehunters can do both tasks. Minehunting pays little attention to the nature of the mine itself. Nor does the method change much.

At the current state of the art, Minehunting remains the best way to deal with influence mines proving to be both safer and more effective than sweeping. Specialized high-frequency sonars and high fidelity sidescaning sonar are used for mine location.

It is slow, but also the most reliable way to remove mines. Minehunting started during the Second World War, but it was only after the war that it became truly effective. Sea mammals mainly the Bottlenose Dolphin have been trained to hunt and mark mines, most famously by the U. Navy Marine Mammal Program. Mine-clearance dolphins were deployed in the Persian Gulf during the Iraq War in The US Navy claims that these dolphins were effective in helping to clear more than antiship mines and underwater booby traps from Umm Qasr Port.

They removed or detonated a variety of German mines, but one particularly defusion-resistant batch—equipped with acutely sensitive pressure, magnetic, and acoustic sensors and wired together so that one explosion would trigger the rest—was simply left undisturbed for years until corrosion would hopefully disable the mines. A more drastic method is simply to run a ship through the minefield, letting other ships safely follow the same path.

However, as mine warfare became more developed this method became uneconomical. Left with a surfeit of idle ships due to the Allied blockade , the Kriegsmarine introduced a ship known as Sperrbrecher "block breaker".

Typically an old cargo ship, loaded with cargo that made her less vulnerable to sinking wood for example , the Sperrbrecher was run ahead of the ship to be protected, detonating any mines that might be in their path. Historical Examples of naval We now loaded with naval stores, and cleared again for Liverpool. Ned Myers James Fenimore Cooper. The Hunted Outlaw Anonymous. My Double Life Sarah Bernhardt.

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A navy or maritime force is the branch of a nation's armed forces principally designated for naval and amphibious warfare; namely, lake-borne, riverine, littoral, or . Naval definition is - of or relating to ships or shipping. How to use naval in a sentence. of or relating to ships or shipping; of or relating to a navy; consisting of or involving warships. Secretary of the Navy Announces New President of the Naval Postgraduate School Secretary of the Navy Richard V. Spencer announced that Vice Adm. (retired) Ann Elisabeth Rondeau will be the next.