_IWM_Q_038114.jpg) HMS Amethyst
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| Class overview | |
|---|---|
| Operators |  Royal Navy |
| Preceded by | Pelorus class |
| Succeeded by | None |
| Subclasses | Amethyst |
| Built | 1903–1905 |
| In commission | 1905–1921 |
| Planned | 8 |
| Completed | 4 |
| Cancelled | 4 |
| Scrapped | 4 |
| General characteristics | |
| Class and type | Topaze-class protected cruiser |
| Displacement | 3,000 long tons (3,048 t) |
| Length | 360 ft (109.7 m) (p/p) |
| Beam | 40 ft (12.2 m) |
| Draught | 16 ft (4.9 m) |
| Installed power |
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| Propulsion |
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| Speed | 21–22 knots (39–41 km/h; 24–25 mph) |
| Complement | 318 |
| Armament | |
| Armour |
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The Topaze-class cruisers (often referred to as the Gem class) were a quartet of third-class protected cruisers built for the Royal Navy in the first decade of the 20th century (four additional ships of the class were cancelled before their keels were laid). HMS Amethyst of this class was the first warship larger than a destroyer to be powered by turbine engines.
As well as a significant historical 'first' this class also embodied many 'lasts' and, despite being units of the Edwardian-period Royal Navy, represented the end of the Victorian-period lineage of protected cruisers in many ways. Amongst the many cruiser classes of the Royal Navy to have been rated as protected cruisers these were; the last to be officially classified as such until the turbine-propelled Bristol class of 1909 appeared; the last to feature the traditional arrangement of raised forecastle & poop connected by amidships bulwarks; and, in the case of three out of the four ships, the last to be designed for propulsion by reciprocating steam engines.
Perhaps most significantly of all, the Gems were the very last third-class cruisers to be so rated in the Royal Navy: the following classes of scout cruisers which featured internal protective decks instead of armour belts were of similar type, but were faster & weaker and intended for a very specialist role; they were accordingly assigned their new official type designation. When the later small turbine-propelled cruisers of the Arethusa class appeared (combining the features of scouts & second-class cruisers, to provide for greater utility & fighting power more in line with the Third Class), the new ships were designated from the outset as 'light armoured cruisers, thus dispensing with the third-class rating entirely.