Topaze-class cruiser

Discussions had been ongoing for several years about a successor to the previous {{sclass|Pelorus|cruiser|4}} before the Admiralty decided on a design in 1901 that was very much larger and faster than the older ships. This represented a shift away from the traditional role of the third-class cruiser: previously best-suited to Imperial defence duties on foreign stations, but now shifting closer to the German concept of a light cruiser; a fast & potent small combatant, suitable for use with the Fleet for scouting duties in the presence of an enemy fleet. In this regard, the Topaze class demonstrates the effect of heightening tensions between the British and Germans, as the Royal Navy's procurement programmes began to emphasise potential combat in the North Sea in anticipation of a possible future war.

The first small cruisers designed for the Royal Navy by the new DNC Sir Philip Watts, the Topaze-class ships had a distinctive three-funneled appearance, with a length between perpendiculars of {{convert|360|ft|m|1}}, a beam of {{convert|40|ft|m|1}} and a draught of {{convert|16|ft|m|1}}. They displaced {{convert|3000|LT|t|0}} and their crew consisted of 313 officers and other ranks.Friedman 2012, pp. 198–211, 335

One objective for the Admiralty with these ships was to evaluate steam turbines against traditional triple-expansion steam engines in a ship larger than a destroyer and {{HMS|Amethyst|1903|2}} became the first cruiser to be equipped with them.Chesneau & Kolesnik, p. 84 Her three sisters used a pair of 4-cylinder triple-expansion steam engines, each driving one shaft, using steam provided by 10 water-tube boilers. The engines were designed to produce a total of {{convert|9800|ihp|lk=in}} which was intended to give a maximum speed of {{convert|21.75|kn|lk=in}}. The three ships easily exceeded their designed power and speeds during their sea trials. They carried a maximum of {{convert|700|LT|t}} of coal which gave them a range of {{convert|7000|nmi|lk=in}} at {{convert|10|kn}} and {{convert|2000|nmi}} at {{convert|20|kn}}.

Amethyst was fitted with a Parsons steam turbine set that drove three shafts using the same number of boilers as her sisters. They delivered enough steam to allow the engines to reach {{convert|12000|ihp|abbr=on}} and her designed speed of {{convert|22.5|kn}}. She also easily exceeded her designed power and speeds during her sea trials, reaching {{convert|23.4|kn}} from {{convert|14300|ihp|abbr=on}}. The turbine proved to be more economical at high speeds than the reciprocating engines of her sisters, but less so at slow speeds, only having an endurance of {{convert|5500|nmi}} at 10 knots, but {{convert|3000|nmi}} at 20 knots.

The main armament of the Topaze class consisted of a dozen quick-firing (QF) QF 4 inch naval gun Mk I – III.Friedman 2011, p. 101 One gun each was mounted on the forecastle and the poop. The remaining ten guns were placed port and starboard amidships, with the forward and aftermost pairs of waist guns being sponsoned and the sides of the forecastle and poop embrasured to allow for axial fire from these four guns. This gave the ships a broadside of seven guns, with at least two guns able to fire through the extreme bow and quarter arcs, or three guns firing dead ahead and dead astern in a chase. Their {{convert|31|lb|adj=on}} shells were fired at a muzzle velocity of {{convert|2335|ft/s}}. The ships also carried eight QF 3-pounder Hotchkiss guns and two above water 18-inch (450 mm) torpedo tubes. The ships' protective deck armour ranged in thickness from {{convert|.75|to|2|in|mm|0}}, being at its thickest on the slopes amidships. The main guns were fitted with {{convert|1|in|adj=on}} gun shields and the conning tower had armour {{convert|3|in}} thick.

{{reflist|30em}}

• {{cite book|title=Conway's All the World's Fighting Ships 1860–1905|editor1-last=Chesneau|editor1-first=Roger|editor2-last=Kolesnik|editor2-first=Eugene M.|publisher=Conway Maritime Press|location=Greenwich|year=1979|isbn=0-8317-0302-4|name-list-style=amp|url-access=registration|url=https://archive.org/details/conwaysallworlds0000unse_l2e2}}
• {{cite book|last=Corbett|first=Julian|author-link=Julian Corbett|title=Naval Operations to the Battle of the Falklands|edition=2nd, reprint of the 1938|series=History of the Great War: Based on Official Documents|date=March 1997 |volume=I|publisher=Imperial War Museum and Battery Press|location=London and Nashville, Tennessee|isbn=0-89839-256-X}}
• {{cite book|last=Friedman|first=Norman|title=British Cruisers of the Victorian Era|year=2012|publisher=Seaforth|location=Barnsley, South Yorkshire, UK|isbn=978-1-59114-068-9}}
• {{cite book|last=Friedman|first=Norman|title=Naval Weapons of World War One|publisher=Seaforth|location=Barnsley, South Yorkshire, UK|year=2011|isbn=978-1-84832-100-7}}
• {{cite book |editor1-last=Gardiner|editor1-first=Robert|editor2-last=Gray|editor2-first=Randal|title=Conway's All the World's Fighting Ships 1906–1921|year=1985|location=Annapolis, Maryland|publisher=Naval Institute Press|isbn=0-85177-245-5|name-list-style=amp}}
• {{cite book|title=The Naval Annual 1912|year=1912|publisher=J Griffin and Co|location=Portsmouth, UK|author=Viscount Hythe}}

{{Commons category|Topaze class cruiser}}

• [http://www.battleships-cruisers.co.uk/gem_class.htm The Topaze or "Gem" class at battleshipscruisers.co.uk]

{{Topaze class cruiser}}

{{WWI British ships}}

Category:Cruiser classes

Category:Ship classes of the Royal Navy