HMS Gannet commissioned into the Royal Navy on 17 April 1879 and served on the Pacific Station until 20 July 1883, sailing over 60,000 miles (96,560 kilometres) during this period. Following a refit in Sheerness (1883-1885), Gannet deployed to the Mediterranean and Red Sea to carry out anti-slavery patrols and support Anglo-Egyptian forces in the Sudan following the death of General Gordon at Khartoum. In late 1888, Gannet helped to lift a rebel siege of the Red Sea port of Suakin in the Sudan, firing over 200 shells from her main armament and almost 1,200 rounds from her Nordenfelt volley guns. Hydrographic surveying work in the Mediterranean and Red Sea occupied Gannet from 10 November 1888 until her decommissioning at Chatham Dockyard on 16 March 1895.
Placed in reserve, in October 1900 Gannet was leased to the South Eastern & Chatham Railway as an accommodation hulk and moored next to Port Victoria Station on the Isle of Grain. In 1903, Gannet was refitted as a Royal Naval Reserve drill ship, renamed HMS President, and moored in the River Thames as the headquarters ship of the London Royal Naval Volunteer Reserve unit. In 1913, President was renamed TS Mercury and moved to the River Hamble to become a dormitory ship for the shoreside boys' nautical training school of the same name. Service as a dormitory ship for the next 54 years allowed TS Mercury to escape the breakers' yard, unlike her Doterel-class sisterships. Following the closure of the Mercury training school in July 1968, the ship reverted back to the Royal Navy, which transferred Gannet to the Maritime Trust in 1971. Chatham Historic Dockyard chartered Gannet in 1987 and commenced restoration work to return the ship to her 1888 appearance. In 1994, Chatham Historic Dockyard Trust purchased Gannet outright and she is now preserved as part of the United Kingdom's National Historic Fleet.
Displacement: 1,130 tons
Length (overall): 57.9 metres (190 feet)
Beam: 10.9 metres (36 feet)
Draught: 4.8 metres (16 feet) maximum
Propulsion: 3 x cylindrical boilers feeding a two-cylinder horizontal compound-expansion steam engine generating 1,107 indicated horsepower and driving a single propeller; ship-rigged sail plan on three masts
Maximum speed: 12.5 knots (23.2 km/h; 14.3 mph) on engine power and 15 knots (27.8 km/h; 14.4 mph)
Range: 2,014 nautical miles (3,730 kilometres) at 11.5 knots (21.3 km/h)
Armament: 2 x 7-inch rifled muzzle-loading guns and 4 x 64-pounder rifled muzzle-loading guns (as built); 2 x 5-inch breech-loading rifled guns, 4 x machine guns, 1 x light gun (added later)
Ship's boats: 1 x 25 foot steam cutter; 1 x 30 foot cutter; 2 x 27 foot whalers; 1 x 16 foot jolly boat; and 1 x 12 foot dinghy
Complement: 13 officers and warrant officers, 27 petty officer, 64 seamen, 11 boys, and 24 Royal Marines (139 total)
Photos taken 21 September 2015
 |
| Like her sisterships, Gannet was designed to patrol the British Empire's overseas colonies, showing the flag, defending British interests and trade, undertaking hydrographic surveys, and conducting anti-slavery and anti-piracy patrols. |
 |
| A starboard bow view of HMS Gannet, one of only three composite-built ships remaining in the world today; the others are the clipper ships Cutty Sark in Greenwich, England and City of Adelaide in Port Adelaide, Australia. |
 |
| HMS Gannet in No. 4 Dry Dock at Chatham Historic Dockyard. Doterel-class sloops such as Gannet were an evolution of the preceding Osprey-class vessels, with a notable difference being the use of a vertical stem rather than the clipper bow as in the Osprey-class. |
 |
| Despite being equipped with a coal-fired steam engine, Gannet's full rig of sails was necessary to ensure the ship could safely cross the world's oceans, given the inefficiency and unreliability of steam engines in the 1870s. |
 |
| Looking forward along the upper deck from the ship's brow. |
 |
| One of HMS Gannet's four 64-pounder rifled muzzle-loading guns. Two 64-pounders, such as this one in the forecastle, sat on pivoting mounts while the other two were located amidships on fixed, broadside mounts. The 64-pounder guns fired a shell weighing 64 pounds (29 kilograms) to a distance of nearly three miles (4.8 kilometres). |
 |
| Looking aft from amidships. Gannet's funnel is in the foreground and the main and mizzen masts can be seen in the further aft. A large canvas awning covers the bridge, located on the poop deck at the stern. |
 |
| Looking forward from the bridge atop the poop deck at Gannet's stern. |
 |
| The steering position, just below the bridge, located on the poop deck above. |
 |
| One of the four Nordenfelt four-barrel organ gun mountings on HMS Gannet. The Nordenfelt gun was an early machine gun, firing 1-inch, 7.25 ounce solid steel bullets in volleys. Bullets were fed into the gun from a hopper with channels feeding rounds into each barrel. |
 |
| One of two 5-inch breech-loading guns mounted on the poop deck at the stern. These guns had a range of five miles (8 kilometres). |
 |
| This cavernous space within Gannet's hull once housed the ship's three coal-fired Humphrey & Tennant cylindrical boilers. Each boiler was 2.4 metres (7 feet 10 inches) in diameter and 4.6 metres (15 feet) long. the boilers were removed in 1895 at the end of Gannet's active service. The adjacent engine room once housed the ship's single Humphrey & Tennant two-cylinder steam engine which drove Gannet's single propeller, measuring four metres (13 feet 1 inch) in diameter. Gannet was actually 2.5 knots (4.6 km/h) faster under sail than under engine power. The iron frames of Gannet's hull are clearly visible with the engine and boiler machinery stripped out. |
 |
| The former forward mess deck in the forecastle of HMS Gannet. |
 |
| A final look at HMS Gannet. The stern houses the Captain's day cabin, which is conveniently close to the ship's bridge on the poop deck. The cabin also accommodated two of Gannet's four Nordenfelt volley guns, as well as the trunking for the lifting propeller, which was raised out of the water when the ship was under sail in order to eliminate drag. |