Humber-class monitor

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HMS Severn off East Africa, 1917
Class overview
Name	Humber class
Builders	Vickers, Barrow in Furness
Operators	Royal Navy Brazilian Navy (intended)
Succeeded by	Abercrombie class
Cost	£155,000 (equivalent to £12.5MM in 2008)
In service	1914-1920
Completed	3
Retired	3
General characteristics
Type	Monitor
Displacement	1,260 long tons (1,280 t) standard 1,520 long tons (1,544 t) full load
Length	266.75 ft (81.3 m)
Beam	49 ft (14.9 m)
Draught	5.6 ft (1.7 m)
Propulsion	2 shaft triple expansion engines 2 Yarrow boilers 1,450 ihp (1,080 kW)
Speed	12 knots (22 km/h) designed, 9.5 knots (18 km/h) in practice
Range	1,650 nautical miles (3,060 km) at 8 knots (15 km/h)
Armament	2 × 6-inch (152 mm) guns in one twin turret 2 × 4.7-inch (119 mm) howitzers 4 × 3-pounder (47mm) guns 1 × 3-pounder (47mm) AA gun 6 × machine guns
Armour	Belt: 3–1.5 in (76–38 mm) Bulkheads: 1.5 in (38 mm) Barbette: 3.5 in (89 mm) Turret face: 4 in (100 mm)
Notes	Mersey and Severn had a turret replaced by two single 6-inch guns in open shielded mountings, Humber had an extra 6-inch gun fitted aft retaining turret

The Humber-class monitors were three large gunboats under construction for the Brazilian Navy in Britain in 1913. Designed for service on the Amazon River, the ships were of shallow draft and heavy armament and were ideally suited to inshore, riverine and coastal work but unsuitable for service at sea, where their weight and light draft reduced their speed from a projected twelve knots to under four. The class comprised Humber, Mersey and Severn. All three were taken over by the Royal Navy shortly before the outbreak of the First World War and were commissioned as small monitors. All three saw extensive service during the war and were sold in 1919.