Minesweeper

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 or a particular vessel type, akin to anti-infantry vs. anti-vehicle mines. Naval mines can be used offensively, to hamper enemy shipping movements or lock vessels into a harbour; or defensively, to protect friendly vessels and create "safe" zones. Mines allow the minelaying force commander to concentrate warships or defensive assets in mine-free areas giving the adversary three choices: undertake an expensive and time-consuming minesweeping effort, accept the casualties of challenging the minefield, or use the unmined waters where the greatest concentration of enemy firepower will be encountered.

The Ming dynasty, officially the Great Ming, was an imperial dynasty of China, ruling from 1368 to 1644 following the collapse of the Mongol-led Yuan dynasty. The Ming dynasty was the last imperial dynasty of China with a ruling elite of Han Chinese, the majority ethnic group in China. Although the primary capital of Beijing fell in 1644 to a rebellion led by Li Zicheng, numerous rump regimes ruled by remnants of the Ming imperial family—collectively called the Southern Ming—survived until 1662.

The Crimean War was fought from October 1853 to February 1856 between Russia and an ultimately victorious alliance of the Ottoman Empire, France, the United Kingdom and Sardinia-Piedmont.

A grappling hook or grapnel is a device that typically has multiple hooks attached to a rope; it is thrown, dropped, sunk, projected, or fastened directly by hand to where at least one hook may catch and hold on to objects. Generally, grappling hooks are used to temporarily secure one end of a rope. They may also be used to dredge for submerged objects.

Naval trawlers are vessels built along the lines of a fishing trawler but fitted out for naval purposes; they were widely used during the First and Second World Wars. Some—known in the Royal Navy as "Admiralty trawlers"— were purpose-built to naval specifications, others adapted from civilian use. Fishing trawlers were particularly suited for many naval requirements because they were robust vessels designed to work heavy trawls in all types of weather, and had large clear working decks. A minesweeper could be created by replacing the trawl with a mine sweep. Adding depth charge racks on the deck, ASDIC sonar below, and a 3-inch (76 mm) or 4-inch (102 mm) gun in the bow equipped the trawler for anti-submarine duties.

The English Channel, also known as simply the Channel, is an arm of the Atlantic Ocean that separates Southern England from northern France. It links to the southern part of the North Sea by the Strait of Dover at its northeastern end. It is the busiest shipping area in the world.

The Flower class comprised five sub-classes of sloops built under the Emergency War Programme for the Royal Navy during World War I, all of which were named after various flowers. They were popularly known as the "herbaceous borders", in humorous reference to a well-known adage about the Royal Navy, as well as to a type of garden border popular in the United Kingdom.

The Kriegsmarine was the navy of Germany from 1935 to 1945. It superseded the Imperial German Navy of the German Empire (1871–1918) and the inter-war Reichsmarine (1919–1935) of the Weimar Republic. The Kriegsmarine was one of three official branches, along with the Heer and the Luftwaffe, of the Wehrmacht, the German armed forces from 1935 to 1945.

An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environments and are an example of an ecotone. Estuaries are subject both to marine influences such as tides, waves, and the influx of saline water, and to fluvial influences such as flows of freshwater and sediment. The mixing of seawater and freshwater provides high levels of nutrients both in the water column and in sediment, making estuaries among the most productive natural habitats in the world.

The landing craft mechanized (LCM) is a landing craft designed for carrying vehicles. They came to prominence during the Second World War when they were used to land troops or tanks during Allied amphibious assaults.

North Korea, officially the Democratic People's Republic of Korea (DPRK), is a country in East Asia. It constitutes the northern half of the Korean Peninsula and shares borders with China and Russia to the north at the Yalu (Amnok) and Tumen rivers, and South Korea to the south at the Korean Demilitarized Zone. North Korea's border with South Korea is a disputed border as both countries claim the entirety of the Korean Peninsula. The country's western border is formed by the Yellow Sea, while its eastern border is defined by the Sea of Japan. North Korea, like its southern counterpart, claims to be the legitimate government of the entire peninsula and adjacent islands. Pyongyang is the capital and largest city.

Kotka is a city in the southern part of the Kymenlaakso province on the Gulf of Finland. Kotka is a major port and industrial city and also a diverse school and cultural city, which was formerly part of the old Kymi parish; later, Kymi with the Haapasaari island and Karhula, the latter of which once separate from Kymi as the market town, were incorporated into Kotka. The neighboring municipalities of Kotka are Hamina, Kouvola and Pyhtää. Kotka belongs to the Kotka-Hamina subdivision, and with Kouvola, Kotka is one of the capital center of the Kymenlaakso region. It is the 19th largest city in terms of population as a single city, but the 12th largest city of Finland in terms of population as an urban area.

Finland, officially the Republic of Finland, is a Nordic country in Northern Europe. It shares land borders with Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of Bothnia to the west and the Gulf of Finland to the south, across from Estonia. Finland covers an area of 338,455 square kilometres (130,678 sq mi) with a population of 5.6 million. Helsinki is the capital and largest city. The vast majority of the population are ethnic Finns. Finnish and Swedish are the official languages, Swedish is the native language of 5.2% of the population. Finland's climate varies from humid continental in the south to the boreal in the north. The land cover is primarily a boreal forest biome, with more than 180,000 recorded lakes.

Type 352 Ensdorf class minesweepers are a class of five minesweepers of the German Navy. They are Type 343 Hameln-class minesweepers that have been upgraded with the Troika Plus system of minesweeping drones

The German Navy is the navy of Germany and part of the unified Bundeswehr, the German Armed Forces. The German Navy was originally known as the Bundesmarine from 1956 to 1995, when Deutsche Marine became the official name with respect to the 1990 incorporation of the East German Volksmarine. It is deeply integrated into the NATO alliance. Its primary mission is protection of Germany's territorial waters and maritime infrastructure as well as sea lines of communication. Apart from this, the German Navy participates in peacekeeping operations, and renders humanitarian assistance and disaster relief. It also participates in anti-piracy operations.

Magnetism is the class of physical attributes that are mediated by a magnetic field, which refers to the capacity to induce attractive and repulsive phenomena in other entities. Electric currents and the magnetic moments of elementary particles giving rise to a magnetic field, which acts on other currents and magnetic moments. Magnetism is one aspect of the combined phenomena of electromagnetism. The most familiar effects occur in ferromagnetic materials, which are strongly attracted by magnetic fields and can be magnetized to become permanent magnets, producing magnetic fields themselves. Demagnetizing a magnet is also possible. Only a few substances are ferromagnetic; the most common ones are iron, cobalt, and nickel and their alloys. The rare-earth metals neodymium and samarium are less common examples. The prefix ferro- refers to iron because permanent magnetism was first observed in lodestone, a form of natural iron ore called magnetite, Fe3O4.

An Oropesa is a streamlined towed body used in the process of minesweeping. The role of the Oropesa is to keep the towed sweep at a determined depth and position from the sweeping ship. Oropesa are standard devices used on Avenger-class mine countermeasures ships.

A minehunter is a naval vessel that seeks, detects, and destroys individual naval mines. Minesweepers, on the other hand, clear mined areas as a whole, without prior detection of mines. A vessel that combines both of these roles is known as a mine countermeasures vessel (MCMV).

HMS Wilton (M1116) was a prototype coastal minesweeper/minehunter for the Royal Navy. She was the first warship in the world to be constructed from glass-reinforced plastic (GRP). Her design was based upon the existing Ton-class minesweepers, and she was fitted with equipment recovered from the scrapped HMS Derriton. The use of GRP gave the vessel a low magnetic signature against the threat of magnetic mines.