HMS Patriot (1916)

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.

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.

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.

A steam turbine is a machine that extracts thermal energy from pressurized steam and uses it to do mechanical work on a rotating output shaft. Its modern manifestation was invented by Charles Parsons in 1884. Fabrication of a modern steam turbine involves advanced metalwork to form high-grade steel alloys into precision parts using technologies that first became available in the 20th century; continued advances in durability and efficiency of steam turbines remains central to the energy economics of the 21st century.

Yarrow boilers are an important class of high-pressure water-tube boilers. They were developed by Yarrow & Co. (London), Shipbuilders and Engineers and were widely used on ships, particularly warships.

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.

Fuel oil is any of various fractions obtained from the distillation of petroleum. Such oils include distillates and residues. Fuel oils include heavy fuel oil, marine fuel oil (MFO), bunker fuel, furnace oil (FO), gas oil (gasoil), heating oils, diesel fuel and others.

A bandstand is a circular, semicircular or polygonal structure set in a park, garden, pier, or indoor space, designed to accommodate musical bands performing concerts. A simple construction, it both creates an ornamental focal point and also serves acoustic requirements while providing shelter for the changeable weather, if outdoors. In form bandstands resemble ornamental European garden gazebos modeled on outdoor open-sided pavilions found in Asian countries from early times.

The M class, more properly known as the Admiralty M class, were a class of 85 destroyers built for the Royal Navy of United Kingdom that saw service during World War I. All ships were built to an identical – Admiralty – design, hence the class name. 18 other vessels which were officially included within the 'M' class were built to variant designs by three specialist builders – 10 by Yarrow, 6 by Thornycroft, and 2 by Hawthorn Leslie; these are covered in other articles.

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.

John I. Thornycroft & Company Limited, usually known simply as Thornycroft was a British shipbuilding firm founded by John Isaac Thornycroft in Chiswick in 1866. It moved to Woolston, Southampton, in 1908, merging in 1966 with Vosper & Company to form one organisation called Vosper Thornycroft. From 2002 to 2010 the company acquired several international and US based defence and services companies, and changed name to the VT Group. In 2008 VT's UK shipbuilding and support operations were merged with those of BAE Systems to create BVT Surface Fleet. In 2010 remaining parts of the company were absorbed by Babcock International who retained the UK and international operations, but sold the US based operations to the American Jordan Company, who took the name VT Group.

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.

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.

HMS Maenad was an Admiralty M-class destroyer which served with the Royal Navy during the First World War. The M class were an improvement on the previous L class, capable of higher speed. The vessel, launched in 1915, served in the Battle of Jutland in 1916, attacking both battleships and destroyers of the German High Seas Fleet. However, the vessel was notorious for undertaking a sharp manoeuvre which obstructed other destroyers in the fleet from attacking. Maenad also undertook anti-submarine patrols. In 1917, the ship mistakenly attacked the British submarine G12 thinking it was a German boat. The submarine escaped with damages. After the armistice that ended of the war, Maenad was placed in reserve until being sold to be broken up in Germany in 1921.

A kite balloon is a tethered balloon which is shaped to help make it stable in low and moderate winds and to increase its lift. It typically comprises a streamlined envelope with stabilising features and a harness or yoke connecting it to the main tether and a second harness connected to an observer's basket.

A depth charge is an anti-submarine warfare (ASW) weapon. It is intended to destroy a submarine by being dropped into the water nearby and detonating, subjecting the target to a powerful and destructive hydraulic shock. Most depth charges use high explosive charges and a fuze set to detonate the charge, typically at a specific depth. Depth charges can be dropped by ships, patrol aircraft, and helicopters.

The action off Lerwick was a naval engagement on 17 October 1917 fought in the North Sea during the First World War. The German light, minelaying cruisers SMS Brummer and Bremse attacked a westbound convoy of twelve colliers and other merchant ships and their escorts, part of the regular Scandinavian convoy. The two escorting destroyers and nine neutral Scandinavian ships were sunk off Shetland, Scotland.

HMS Strongbow was an M-class destroyer built for the British Royal Navy during the First World War. The ship was launched in September 1916 and entered service in November that year. Stongbow was sunk on 17 October 1917 by the German light cruisers SMS Bremse and Brummer in the North Sea, when escorting a convoy of merchant ships from Norway.

The Atlantic Fleet was a naval fleet of the Royal Navy. It existed for two separate periods; 1909 until 1914, and then 1919 until 1932.