HMS Castor: one of a class of four light cruisers [sister ships were HMS Cambrian, HMS Canterbury, and HMS Constance]. Design of this class was based on the earlier cruisers HMS Champion and HMS Calliope, which, in turn, were based on the HMS Caroline class, using the same hull as the Carolines but with two funnels and maximum armor thickness of 4" as opposed to 3" in the Carolines.
Builder: Cammell Laird [Birkenhead] Laid down: October, 1914; launched: July, 1915; Completed: November, 1915. Displacement: 3,750 tons Crew: 323 Length: 446' o.a.; beam: 41.5'; draught: 16.25' Guns: 4 X 6", 2 X 3" aa Torpedo tubes: 4 X 21" Machinery: 8 Yarrow boilers. Parsons turbines. Oil fuel. Designed performance: 40,000shp = 28.5 kts. On trials: 42,337 shp.
Castor normally served as the flagship of Commodore [D], and served as such at the Battle of Jutland.
The Caroline-class were all launched in 1914 and commissioned in 1915.
HM ships Calliope and Champion had all geared turbines, the first RN cruisers to be fitted with them.
The HMS Caroline remains in service as of 2004, and serves as HQ and training ship to the Royal Naval Reserve in Northern Ireland, duties that she first started in 1924.