The
Arethusa-class cruisers were intended to lead
destroyer flotillas and defend the fleet against attacks by enemy destroyers. The ships were
long overall, with a
beam of and a deep
draught of .
Displacement was at normal and at full load.
Royalist was powered by four
Parsons steam turbines, each driving one
propeller shaft, which produced a total of . The turbines used steam generated by eight
Yarrow boilers which gave her a speed of about . She carried tons of
fuel oil The main armament of the
Arethusa-class ships was two
BL 6-inch (152 mm) Mk XII guns that were mounted on the centreline fore and aft of the
superstructure and six
QF 4-inch Mk V guns in waist mountings. They were also fitted with a single
QF 3-pounder anti-aircraft gun and four British 21-inch torpedo|
torpedo tubes in two twin mounts. ==Construction and career==