The Alarm-class torpedo gunboat was the penultimate class of torpedo gunboat built for the Royal Navy. The class was contemporary with the early torpedo boat destroyers, which were faster and thus better suited to pursuit of enemy torpedo boats. By World War I the class had either been sold, converted to submarine depot ships or minesweepers, or reduced to harbour service. Three of the class were lost during World War I while serving in the minesweeping role.
The Alarm class was designed by Sir William White in 1889 as an enlarged version of his previous Sharpshooter class. They had a length overall of 242feet, a beam of 27feet and a displacement of 810 tons. They were engined with two sets of vertical triple-expansion steam engines, two locomotive boilers, and twin screws. This layout produced 3500ihp, giving them a speed of with forced draught. They carried between 100 and 160 tons of coal and were manned by 91 sailors and officers.
While officially classed with the Alarm class, the Speedy was actually a separate design. The Naval Defence Act of 1889 authorised the purchase of an Alarm-class torpedo gunboat built to a design by John I. Thornycroft & Company and built in their yard at Chiswick. Speedy was a three-funnelled vessel (compared to the two-funnelled Admiralty design), but the key difference was the use of water-tube boilers instead of locomotive-type boilers; she produced at least 5000ihp and could make . The use of water-tube boilers was a key feature of the new torpedo boat destroyers that would make torpedo gunboats (including the Alarm class) obsolete.
At build the class was fitted with two QF 4.7inches/45-pounder guns, four 3-pounder guns and one Gardner machine gun. Five 14inches torpedo tubes were fitted in the first five vessels, but this was changed to three 18-inch (450mm) torpedo tubes in the rest of the class. They were arranged as a pair of revolving deck mounts, a pair of fixed deck mounts (deleted in the later vessels) and a single bow-mounted tube; three reloads were provided.
| Name | Ship Builder | Laid down | Launched | Completed | Fate | |
|---|---|---|---|---|---|---|
| Naval Construction & Armament, Barrow | 7 September 1891 | 14 May 1892 | June 1893 | Became a minesweeper in 1909. Sunk by a mine off the west coast of Scotland on 7 April 1917 | ||
| Sheerness Dockyard | 11 January 1890 | 14 June 1892 | May 1893 | Became a minesweeper in 1909. Sold for breaking on 30 July 1920 | ||
| Sheerness Dockyard | 11 January 1890 | 15 June 1892 | 9 October 1894 | Became a minesweeper in 1909. Became a depot ship for submarines in 1910 (guns retained). Sold for breaking on 22 October 1919 | ||
| Laird Brothers, Birkenhead | 8 October 1891 | 7 September 1892 | January 1894 | Became a depot ship for submarines in 1907 (armament removed). Renamed Vulcan II in June 1919 (or April 1920?). Sold for breaking in August 1924 and resold on 9 October 1924 | ||
| Sheerness Dockyard | 25 June 1891 | 13 September 1892 | November 1893 | Became a minesweeper in 1909. Sold for breaking on 14 July 1920 and broken up in Germany in 1922 | ||
| Sheerness Dockyard | 25 June 1891 | 13 September 1892 | March 1894 | Sold for breaking on 9 April 1907 | ||
| Naval Construction & Armament, Barrow | 14 September 1891 | 24 September 1892 | July 1893 | Sold on 11 July 1905 | ||
| Laird Brothers, Birkenhead | 26 October 1891 | 6 December 1892 | January 1894 | Sold for breaking on 4 April 1905 | ||
| Naval Construction & Armament, Barrow | 17 September 1891 | 17 December 1892 | 25 April 1893 | Became a minesweeper in 1909. Torpedoed by U-12 off Deal on 11 November 1914 | ||
| Thornycroft, Chiswick | 4 January 1892 | 18 May 1893 | 20 February 1894 | Became a minesweeper in 1909. Sunk by a mine off the Humber on 3 September 1914 | ||
| Devonport Dockyard | 21 October 1889 | 12 July 1893 | May 1894 | Reduced to harbour service in 1910 and used as training ship at Devonport. Sold for breaking on 27 May 1919 |