HMS Tactician (1918)

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.

John Brown and Company of Clydebank was a Scottish marine engineering and shipbuilding firm. It built many notable and world-famous ships including RMS Lusitania, RMS Aquitania, HMS Hood, HMS Repulse, RMS Queen Mary, RMS Queen Elizabeth and the Queen Elizabeth 2.

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.

Dalmuir is an area nine miles northwest of Glasgow, Scotland, on the western side of Clydebank, and part of West Dunbartonshire Council Area. The name is a lowland Scots derivation of the Gaelic meaning Big Field. The area was originally two separate villages with Dalmuir Shore joining with Clydebank in 1886 and Dalmuir Village in 1906, during a period of rapid industrialization and expansion. Dalmuir is bounded by the village of Old Kilpatrick to the west, the Mountblow and Parkhall housing schemes to the north, and the Clydebank town centre area to the east. To the south is the River Clyde.

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.

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.

HMAS Tasmania (H25) was an Admiralty S class destroyer of the Royal Australian Navy (RAN). Built for the Royal Navy during World War I, the ship was not completed until 1919, and spent a year commissioned but not operational in British service before being transferred to the RAN at the start of 1920. The destroyer's career was uneventful, with almost all of it spent in Australian waters. Tasmania was decommissioned in 1930, and was sold for ship breaking in 1937.

The Grand Fleet was the main battlefleet of the Royal Navy during the First World War. It was established in August 1914 and disbanded in April 1919. Its main base was Scapa Flow in the Orkney Islands.

The Armistice of 11 November 1918 was the armistice signed at Le Francport near Compiègne that ended fighting on land, sea, and air in World War I between the Entente and their last remaining opponent, Germany. Previous armistices had been agreed with Bulgaria, the Ottoman Empire and Austria-Hungary. It was concluded after the German government sent a message to American president Woodrow Wilson to negotiate terms on the basis of a recent speech of his and the earlier declared "Fourteen Points", which later became the basis of the German surrender at the Paris Peace Conference, which took place the following year.

The Nore is a long bank of sand and silt running along the south-centre of the final narrowing of the Thames Estuary, England. Its south-west is the very narrow Nore Sand. Just short of the Nore's easternmost point where it fades into the channels it has a notable point once marked by a lightship on the line where the estuary of the Thames nominally becomes the North Sea. A lit buoy today stands on this often map-marked divisor: between Havengore Creek in east Essex and Warden Point on the Isle of Sheppey in Kent.

The London Naval Treaty, officially the Treaty for the Limitation and Reduction of Naval Armament, was an agreement between the United Kingdom, Japan, France, Italy, and the United States that was signed on 22 April 1930. Seeking to address issues not covered in the 1922 Washington Naval Treaty, which had created tonnage limits for each nation's surface warships, the new agreement regulated submarine warfare, further controlled cruisers and destroyers, and limited naval shipbuilding.