page_title: HMS Polyphemus (1881)
section_title: Armament
hierarchical_section_title: HMS Polyphemus (1881) / Armament
caption_attribution_description: English: Ram and bow rudders of HMS Polyphemus in drydock at Malta. This ram is built-in a torpedo tube.
context_page_description: The third HMS Polyphemus was a Royal Navy torpedo ram, serving from 1881 until 1903. A shallow-draft, fast, low-profile vessel, she was designed to penetrate enemy harbours at speed and sink anchored ships. Designed by Nathaniel Barnaby primarily as a protected torpedo boat, the ram was provided very much as secondary armament.
  It has been suggested that H. G. Wells’ fictional HMS Thunder Child from his novel The War of the Worlds may have been based on this ship, in part because he described Thunder Child as an ironclad torpedo ram, and Polyphemus was the only ship of this type which the Royal Navy possessed.
context_section_description: The ship had five submerged 14-inch-diameter torpedo tubes, and carried 18 Mark II torpedoes. With a range of just 600 yards, these had a 26-pound guncotton charge and a speed of 18 knots, only marginally faster than Polyphemus.
  The centre torpedo tube was fitted with a combined cast steel bow cap and ram.  It hinged upwards to open, and considerable effort went into selecting the best hydrodynamic design through model testing since its size and location were found to have a major impact on the ship’s performance. It had the same effect on Polyphemus’ hull as the bulbous bow fitted to many modern ships.  
  The bow also had a balanced two-bladed rudder fitted into it, which could be retracted into the hull, that allowed the ship to be manoeuvrable when going astern. It also slightly reduced the diameter of the turning circle (by 12 percent) when the ship was moving forwards. 
  Her original gun armament consisted of 6 twin-barreled Nordenfelt 25mm (1-inch) automatic guns, although later in the 1880s they were replaced by 6 single Hotchkiss 3-pounder (47mm) quick-firing guns. Her deck was armoured with 3 inches (76.2mm) of armour plate. This armament was consistent with slightly later torpedo boats, although they usually carried fewer guns.
caption: HMS Polyphemus' ram and bow rudders. A torpedo tube ran down the centre of the ram.
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