 The Active @-@ class ships were the last class of turbine @-@ powered scout cruisers ordered by the Admiralty . These ships were intended to work with destroyer flotillas , leading their torpedo attacks and backing them up when attacked by other destroyers , although they quickly became less useful as destroyer speeds increased before the First World War . Amphion had a length between perpendiculars of 405 feet ( 123 @.@ 4 m ) , a beam of 41 feet ( 12 @.@ 5 m ) and a draught of 14 feet 6 inches ( 4 @.@ 4 m ) . She displaced 3 @,@ 340 long tons ( 3 @,@ 394 t ) at normal load and 3 @,@ 945 long tons ( 4 @,@ 008 t ) at deep load . Her crew consisted of 289 officers and other ranks . 
