The third HMS Polyphemus was a Royal Navy

Royal Navy

The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 torpedo ram

Torpedo ram

A torpedo ram is a type of torpedo boat combining a ram with torpedo tubes. Incorporating design elements from the cruiser and the monitor, it was intended to provide small and inexpensive weapon systems for coastal defence and other littoral combat....

, 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

Nathaniel Barnaby

Sir Nathaniel Barnaby, KCB was Chief Constructor of the Royal Navy from 1872 to 1885....

 primarily as a protected

Protected cruiser

The protected cruiser is a type of naval cruiser of the late 19th century, so known because its armoured deck offered protection for vital machine spaces from shrapnel caused by exploding shells above...

 torpedo boat

Torpedo boat

A torpedo boat is a relatively small and fast naval vessel designed to carry torpedoes into battle. The first designs rammed enemy ships with explosive spar torpedoes, and later designs launched self-propelled Whitehead torpedoes. They were created to counter battleships and other large, slow and...

, the ram

Naval ram

A naval ram was a weapon carried by varied types of ships, dating back to antiquity. The weapon consisted of an underwater prolongation of the bow of the ship to form an armoured beak, usually between six and twelve feet in length...

 was provided very much as secondary armament.

It has been suggested that H. G. Wells

H. G. Wells

Herbert George Wells was an English author, now best known for his work in the science fiction genre. He was also a prolific writer in many other genres, including contemporary novels, history, politics and social commentary, even writing text books and rules for war games...

’ fictional HMS Thunder Child

HMS Thunder Child

HMS Thunder Child is the name of the fictional ironclad torpedo ram of the Royal Navy that is destroyed by Martian fighting-machines in H. G. Wells' The War of the Worlds...

 from his novel The War of the Worlds may have been based on this ship, in part because he described Thunder Child as a torpedo ram, and Polyphemus was the only ship of this type which the Royal Navy possessed.

Design

The Admiralty

Admiralty

The Admiralty was formerly the authority in the Kingdom of England, and later in the United Kingdom, responsible for the command of the Royal Navy...

 set up the "Torpedo Committee" in 1872 to examine ways in which the newly invented Whitehead

Robert Whitehead

Robert Whitehead was an English engineer. He developed the first effective self-propelled naval torpedo. His company, located in the Austrian naval centre in Fiume, was the world leader in torpedo development and production up to the First World War.- Early life:He was born the son of a...

 torpedo

Torpedo

The modern torpedo is a self-propelled missile weapon with an explosive warhead, launched above or below the water surface, propelled underwater towards a target, and designed to detonate either on contact with it or in proximity to it.The term torpedo was originally employed for...

 could be launched at sea. The Royal Navy's first purpose-built torpedo launching ship was HMS Vesuvius, which, with a maximum speed of less than 10 knots, was intended to stealthily approach within a few hundred yards of enemy ships at night to launch her torpedoes. Leading on from this, Barnaby and his assistant J Dunn, proposed in the mid-1870s a fast cigar-shaped vessel with five submerged torpedo tubes and protected by 2 inches of armour over the deck. The design was modified in late 1875 into a larger vessel equipped with a ram. Early in 1876 the design was modified again into a 240 feet (73.2 m) unarmoured torpedo ram with a top speed of 17 knots. Later the design was modified yet again to have armour added to the exposed steel deck.

The ship was equipped with a 250-ton cast iron keel which could be released in an emergency to increase the buoyancy of the hull. It was held in place by two spindles which both had to be turned to release the keel and which were tested fortnightly.

The ship was equipped with twin boiler and engine rooms, and a low turtle-back hull which was almost submerged when the vessel was travelling at speed, and had a normal bunker capacity of 200 tons of coal, and 300 tons maximum.

Construction and planned sister-ships

The Polyphemus was ordered on 5 February 1878 and laid down on 21 September 1878 at Chatham Naval Dockyard. She was launched on 15 June 1881 and completed in September 1882. A second ship to the same design was ordered from Chatham on 30 December 1881 but was cancelled on 10 November 1882 without being either laid down or named. Another order to the same design was placed at Chatham on 6 March 1885, the ship to have been named HMS Adventure, but this was also cancelled on 12 August 1885.

Armament

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

Bulbous bow

A bulbous bow is a protruding bulb at the bow of a ship just below the waterline. The bulb modifies the way the water flows around the hull, reducing drag and thus increasing speed, range, fuel efficiency, and stability...

 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.

Other innovations

The ship was the first Royal Navy vessel to be fitted with 80-volt electric lighting. This was adopted by the Royal Navy in 1882 following a fatal electrocution

Electric shock

Electric Shock of a body with any source of electricity that causes a sufficient current through the skin, muscles or hair. Typically, the expression is used to denote an unwanted exposure to electricity, hence the effects are considered undesirable....

 aboard HMS Inflexible

HMS Inflexible (1876)

HMS Inflexible was a Victorian ironclad battleship carrying her main armament in centrally placed turrets. The ship was constructed in the 1870s for the Royal Navy to oppose the perceived growing threat from the Italian Regia Marina in the Mediterranean.The Italian Navy had started constructing a...

, which had an 800-volt circuit.

The vessel was fitted with a flying deck which housed the bridge and machine guns. It was designed so that if the vessel sank it would float off as two seaworthy rafts.

1885 Berehaven trial

In 1885 the ship undertook a simulated attack on a fleet at anchor at Berehaven. The principal object of this was to test tactics for a possible attack on Kronstadt

Kronstadt

Kronstadt , also spelled Kronshtadt, Cronstadt |crown]]" and Stadt for "city"); is a municipal town in Kronshtadtsky District of the federal city of St. Petersburg, Russia, located on Kotlin Island, west of Saint Petersburg proper near the head of the Gulf of Finland. Population: It is also...

 Harbour in the event of the threatened war with Russia

Russia

Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

. Booms and nets (to catch propellers) were laid across the channel behind Bereshaven, along with small observation mines and the area covered by machine guns and torpedo boats. Polyphemus launched a simulated attack on 30 June, evading around ten torpedoes fired by 6 torpedo boats during her two-mile run-in and easily smashed through the booms and a 5-inch steel hawser holding them in place.

Despite this success, no further vessels were ordered by the Royal Navy, possibly because the development of quick-traversing and quick-firing guns as she entered service had rendered the concept behind her design less practical. When she was designed, the only guns capable of penetrating her armour were too slow to train and fire to have much chance of hitting such a fast-moving ship, but by the time that she entered service a few years later, this was no longer true.

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