HMS Stronghold

The Admiralty was a department of the Government of the United Kingdom responsible for the command of the Royal Navy until 1964, historically under its titular head, the Lord High Admiral – one of the Great Officers of State. For much of its history, from the early 18th century until its abolition, the role of the Lord High Admiral was almost invariably put "in commission" and exercised by the Lords Commissioner of the Admiralty, who sat on the governing Board of Admiralty, rather than by a single person. The Admiralty was replaced by the Admiralty Board in 1964, as part of the reforms that created the Ministry of Defence and its Navy Department.

The first R class were a class of 62 destroyers built between 1916 and 1917 for the Royal Navy. They were an improvement, specifically in the area of fuel economy, of the earlier Admiralty M-class destroyers. The most important difference was that the Admiralty R class had two shafts and geared turbines, compared with the three shafts and direct turbines of the Admiralty M class, but in appearance the R class could be distinguished from its predecessors by having the after 4-inch gun mounted in a bandstand. The Admiralty ordered the first two of this class of ships in May 1915. Another seventeen were ordered in July 1915, a further eight in December 1915, and a final twenty-three in March 1916.

Length overall is the maximum length of a vessel's hull measured parallel to the waterline. This length is important while docking the ship. It is the most commonly used way of expressing the size of a ship, and is also used for calculating the cost of a marina berth.

Length between perpendiculars is the length of a ship along the summer load line from the forward surface of the stem, or main bow perpendicular member, to the after surface of the sternpost, or main stern perpendicular member. When there is no sternpost, the centerline axis of the rudder stock is used as the aft end of the length between perpendiculars.

The beam of a ship is its width at its widest point. The maximum beam (BMAX) is the distance between planes passing through the outer extremities of the ship, beam of the hull (BH) only includes permanently fixed parts of the hull, and beam at waterline (BWL) is the maximum width where the hull intersects the surface of the water.

The draft or draught of a ship's hull is the vertical distance between the waterline and the bottom of the hull (keel). The draught of the vessel is the maximum depth of any part of the vessel, including appendages such as rudders, propellers and drop keels if deployed. Draft determines the minimum depth of water a ship or boat can safely navigate. The related term air draft is the maximum height of any part of the vessel above the water.

The displacement or displacement tonnage of a ship is its weight. As the term indicates, it is measured indirectly, using Archimedes' principle, by first calculating the volume of water displaced by the ship, then converting that value into weight. Traditionally, various measurement rules have been in use, giving various measures in long tons. Today, tonnes are more commonly used.

The knot is a unit of speed equal to one nautical mile per hour, exactly 1.852 km/h. The ISO standard symbol for the knot is kn. The same symbol is preferred by the Institute of Electrical and Electronics Engineers (IEEE), while kt is also common, especially in aviation, where it is the form recommended by the International Civil Aviation Organization (ICAO). The knot is a non-SI unit. The knot is used in meteorology, and in maritime and air navigation. A vessel travelling at 1 knot along a meridian travels approximately one minute of geographic latitude in one hour.

The kilometre per hour is a unit of speed, expressing the number of kilometres travelled in one hour.

Miles per hour is a British imperial and United States customary unit of speed expressing the number of miles travelled in one hour. It is used in the United Kingdom, the United States, and a number of smaller countries, most of which are UK or US territories, or have close historical ties with the UK or US.

Laying the keel or laying down is the formal recognition of the start of a ship's construction. It is often marked with a ceremony attended by dignitaries from the shipbuilding company and the ultimate owners of the ship.

Greenock is a town and administrative centre in the Inverclyde council area in Scotland, United Kingdom and a former burgh within the historic county of Renfrewshire, located in the west central Lowlands of Scotland. It forms part of a contiguous urban area with Gourock to the west and Port Glasgow to the east.

Ceremonial ship launching involves the performance of ceremonies associated with the process of transferring a vessel to the water. It is a nautical tradition in many cultures, dating back thousands of years, to accompany the physical process with ceremonies which have been observed as public celebration and a solemn blessing, usually but not always, in association with the launch itself.

His Majesty's Naval Base, Portsmouth is one of three operating bases in the United Kingdom for the Royal Navy. Portsmouth Naval Base is part of the city of Portsmouth; it is located on the eastern shore of Portsmouth Harbour, north of the Solent and the Isle of Wight. Until the early 1970s, it was officially known as Portsmouth Royal Dockyard ; thereafter the term 'Naval Base' gained currency, acknowledging a greater focus on personnel and support elements alongside the traditional emphasis on building, repairing and maintaining ships. In 1984 Portsmouth's Royal Dockyard function was downgraded and it was formally renamed the 'Fleet Maintenance and Repair Organisation' (FMRO). The FMRO was privatized in 1998, and for a time, shipbuilding, in the form of block construction, returned. Around 2000, the designation HMS Nelson was extended to cover the entire base.

An aircraft catapult is a device used to allow aircraft to take off from a very limited amount of space, such as the deck of a vessel, but can also be installed on land-based runways in rare cases. It is now most commonly used on aircraft carriers, as a form of assisted take off.

Cordite is a family of smokeless propellants developed and produced in the United Kingdom since 1889 to replace black powder as a military propellant. Like modern gunpowder, cordite is classified as a low explosive because of its slow burning rates and consequently low brisance. These produce a subsonic deflagration wave rather than the supersonic detonation wave produced by brisants, or high explosives. The hot gases produced by burning gunpowder or cordite generate sufficient pressure to propel a bullet or shell to its target, but not so quickly as to routinely destroy the barrel of the gun.

The Royal Aircraft Establishment Larynx was an early British pilotless aircraft, to be used as a guided anti-ship weapon. Started in September 1925, it was an early cruise missile guided by an autopilot.

The Bristol Channel is a major inlet in the island of Great Britain, separating South Wales from Devon and Somerset in South West England. It extends from the lower estuary of the River Severn to the North Atlantic Ocean. It takes its name from the English city of Bristol, and is over 30 miles (50 km) wide at its western limit.

HMS Tara was an S-class destroyer, which served with the Royal Navy. Launched on 7 August 1918, the vessel entered service at the closing of the First World War. The ship joined the Fourteenth Destroyer Flotilla of the Grand Fleet but was placed in Reserve at Nore in 1919. Tara deteriorated over the following years and was sold to be broken up on 17 December 1931 after the signing of the London Naval Treaty that limited the amount of destroyer tonnage the Navy could retain.

A minelayer is any warship, submarine or military aircraft deploying explosive mines. Since World War I the term "minelayer" refers specifically to a naval ship used for deploying naval mines. "Mine planting" was the term for installing controlled mines at predetermined positions in connection with coastal fortifications or harbor approaches that would be detonated by shore control when a ship was fixed as being within the mine's effective range.

The battlecruiser was a type of capital ship of the first half of the 20th century. These were similar in displacement, armament and cost to battleships, but differed in form and balance of attributes. Battlecruisers typically had thinner armour and a somewhat lighter main gun battery than contemporary battleships, installed on a longer hull with much higher engine power in order to attain greater speeds. The first battlecruisers were designed in the United Kingdom, as a development of the armoured cruiser, at the same time as the dreadnought succeeded the pre-dreadnought battleship. The goal of the design was to outrun any ship with similar armament, and chase down any ship with lesser armament; they were intended to hunt down slower, older armoured cruisers and destroy them with heavy gunfire while avoiding combat with the more powerful but slower battleships. However, as more and more battlecruisers were built, they were increasingly used alongside the better-protected battleships.

HMS Repulse was one of two Renown-class battlecruisers built for the Royal Navy during the First World War. Originally laid down as an improved version of the Revenge-class battleship, her construction was suspended on the outbreak of war because she would not be ready in time. Admiral Lord Fisher, upon becoming First Sea Lord, gained approval for her to resume construction as a battlecruiser that could be built and enter service quickly. The Director of Naval Construction (DNC), Eustace Tennyson-d'Eyncourt, quickly produced an entirely new design to meet Admiral Lord Fisher's requirements and the builders agreed to deliver the ship in 15 months. They did not quite meet that ambitious goal, but the ship was delivered a few months after the Battle of Jutland in 1916. Repulse and her sister ship Renown, were the world's fastest capital ships upon completion.