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Le due navi corazzate classe Scorpion, La HMS Scorpion e la HMS Wivern, furono navi da battaglia ordinate dalla Marina Confederata nel 1862. Nel 1863 furono sequestrate dai britannici per evitarne la consegna. Questa avrebbe infatti violato il Foreign Enlistment Act, che vietava ai sudditi britannici di costruire o armare qualsiasi nave per stati in guerra con governi amici della Gran Bretagna. La classe Scorpion era composta da navi con alberatura tradizionale e torri girevoli, ognuna delle quali era progettata contenere un paio di cannoni pesanti ad avancarica. Nel 1864 furono comprate dal governo britannico per servire nella Royal Navy e servirono brevemente nella Channel Fleet prima di diventare le navi di guardia ai porti delle Bermuda e di Hong Kong. La Scorpion fu venduta nel 1903 ed affondò mentre era trainata per essere portata al luogo di demolizione, mentre la Wivern fu venduta per essere demolita nel 1922.
Progetto e descrizione
Nel marzo 1862 il capitano James D. Bulloch, agente della Marina Confederata, firmò un contratto con la Laird & Son Co. per due navi da battaglia bitorretta, progettate per speronare, per un costo di 93 750 £ ad unità, escluse armi e munizioni. Erano state pensate, insieme ad altre unità, per forzare il blocco federale sulle città costiere del Sud e per prendere in ostaggio alcune città del Nord per poter poi chiedere un riscatto.
Le navi avevano una lunghezza tra le perpendicolari di 68,4 m, un baglio massimo di 12,9 m e un immersione di 5,2 m a pieno carico, dislocando 2795 t. Lo scafo era diviso da 12 paratie stagne e la nave aveva un doppio fondo sotto la sala macchine. L'equipaggio consisteva in 152 tra ufficiali e marinai.
Le torrette dei cannoni, progettate dal capitano Coles della Royal Navy, erano posizionate su piastre circolari girevoli che erano costruite su una piattaforma radiale di ferro con bracci appoggiati su ruote smussate da 457 mm di diametro. Ogni torretta necessitava di 18 uomini per girare attraverso un sistema a cremagliera. Per una rotazione di 360° serviva circa un minuto e potevano essere ruotate sia da dentro che da fuori. In casi d'emergenza la torretta poteva essere ruotata con un paranco o utilizzando un cabestano. Per ridurre l'entrata d'acqua tra la torretta e il ponte fu utilizzato uno strato di cuoio sul fondo della torretta. Come la maggioranza delle navi corazzate dell'epoca fu costruita con un rostro di metallo fucinato.
La nave aveva 1,8 m di bordo libero, che poteva essere aumentato di 1,5 m tramite un'impavesata incernierata a lato delle torrette. In servizio le navi si rivelarono buone piattaforme con una buona tenuta di mare, anche se tendevano a rollare pesantemente e quindi ad avere i ponti spesso bagnati. Il fondo piatto e il piccolo timone causavano però problemi nella navigazione con vento. Per la loro tenuta di mare e i loro potenti cannoni le due navi furono reputate superiori a qualsiasi monitore della US Navy.
Propulsione
La classe Scorpion aveva due motori a vapore orizzontali ad azione diretta, costruiti da Lairds, che muovevano un'elica singola da 4,3 m a tre pale. I motori ricevevano il vapore grazie a 4 caldaie tubolari che lavoravano alla pressione di 20 psi (138 kPa). I motori producevano un totale di 1080 kW, che davano alla nave una velocità massima di 10,5 nodi. La Wivern raggiunse la velocità massima di 11 nodi durante le prove in mare del 4 ottobre1865. Le navi trasportavano 341 t di carbone, abbastanza per percorrere 1210 miglia nautiche a 10 nodi. Le navi avevano un armo a brigantino a palo con tre alberi. La Scorpion ebbe sartie convenzionali per tenere l'albero in posizione, ma la Wivern fu la prima nave ad avere alberi a tripode per ridurre l'interferenza con gli angoli di tiro delle torrette. Il fumaiolo era semi-ritraibile per ridurre la resistenza al vento durante la navigazione a vela.
Armamento
No ordnance had been ordered by the Confederates before the ships were seized in 1863, but in British service they mounted a pair of 9-inch rifled muzzle-loading guns in each turret. The shell of the 9-inch (229 mm) gun weighed 254 pounds (115.2 kg) while the gun itself weighed 12 long tons (12 t). The gun fired its shell at a muzzle velocity of 1,420 ft/s (430 m/s) and was credited with the ability to penetrate a nominal 11.3 inches (290 mm) of wrought iron armour at 100 yards (91 m). The guns could fire both solid shot and explosive shells. According to Parkes, going from full depression to full elevation supposedly took one hour in smooth water and with an even keel!
Corazzatura
The Scorpion-class ships had a complete waterline belt of wrought iron that was 4.5 inches (114 mm) thick amidships and thinned to 3 inches (76 mm) at the bow and 2.5 inches (64 mm) at the stern. It completely covered the hull from the upper deck to 3 feet 3 inches (0.99 m) below the waterline. The armour protection of the polygonal turrets was quite elaborate. The inside of the turret was lined with .5 inches (12.7 mm) of iron boiler plate to which T-shaped beams were bolted. The space between the beams was filled with 10 inches (254 mm) of teak. This was covered by an iron lattice .75 inches (19.1 mm) thick that was covered in turn by 8 inches (203 mm) of teak. The 5.5-inch (140 mm) iron plates were bolted to the outside using bolts that ran through to the interior iron "skin". The area around the gun ports was reinforced by 4.5-inch plates to give a total thickness of 10 inches. The turret roof consisted of T-shaped beams covered by 1-inch (25 mm) iron plates. Holes in the roof were provided for ventilation and for the gun captain to use to aim the turret.
Costruzione
In his letter of 29 October 1862, Navy Secretary Stephen Mallory named yard number 294 as North Carolina and number 295 as Mississippi. In January 1863 the Foreign Secretary, Lord Russell, notified Bulloch, who had purchased the ships in his own name, that the ships would be prevented from sailing if they were doing so to form part of the fleet of a nation currently at war. Bulloch therefore transferred ownership to some French bankers in June 1863, nominally on behalf of the Egyptian government, with the intention of transferring them to the Confederate flag once they were at sea. The Khedive was attempting to acquire warships, so this was superficially plausible. North Carolina, later HMS Scorpion, was given the cover name of El Toussan and Mississippi, later HMS Wivern, received the name of El Monnassir. Lord Russel, prompted by the protests of the U.S. Ambassador, Charles F. Adams queried the Egyptian government directly and confirmed that this was merely a subterfuge to disguise the true ownership of the vessels. The Admiralty was prompted to send a guard ship, HMS Majestic, to watch over the newly launched El Toussan after Lairds had made a request to begin sea trials in September. The Liverpool Collector of Customs was instructed not to let the ship leave her graving dock under any circumstances and the Surveyor of Customs finally seized the ships on 9 October.
The legality of this seizure was seriously disputed, but the British government had already been somewhat embarrassed by the activities of the Alabama, a ship also built by Laird Son & Co and operated as a commerce raider by the Confederate Navy. In order to overshadow discussions as to the legality of their action, the British government purchased the ships on 8 August 1864 for £25,000 in excess of the contract price.
| Ship | Builder | Laid down | Launched | Commissioned | Fate | Cost |
|---|---|---|---|---|---|---|
| HMS Scorpion | Laird & Son Co., Birkenhead | Aprile 1862 | 4 luglio 1863 | Luglio 1865 | Venduta nel febbraio 1903, affondata al traino | 111 614 £ |
| HMS Wivern | Aprile 1862 | 29 agosto 1863 | 28 settembre 1865 | Venduta nel giugno 1922 | 118 769 £ |
Servizio
Both ships were assigned to the Channel Fleet upon commissioning in 1865. Scorpion was refitted in 1867 with a flying bridge that connected the forecastle to the poop, above the tops of the turrets, and her sailing rig was reduced to a fore-and-aft rig. The ship recommissioned in 1868 for another tour with the Channel Fleet. She arrived in Bermuda in November 1869 where she became the local guard ship. In 1873 a proposal was made to remove her poop and forecastle, masts and deck fitting to convert her to a harbour defence monitor with all-around fire, but this was deemed too expensive and the project was abandoned in 1878. At some point during her service in Bermuda her rigging was removed and she was reduced to simple pole masts. The ship was fitted with searchlights and quick-firing guns in 1890. Scorpion was sunk as a target in 1901; she was raised in 1902 and sold in February 1903 for £736. She sank while under tow to Boston, Massachusetts.
Wivern burst one of her 9-inch guns in 1867, but none of the 13 people in the turret was injured. She was given the same sort of refit as her sister ship in Devonport beginning in August 1868. The ship became the guard ship at Hull from January through October 1870 and was then placed in reserve from 1870 until 1880. That year she was sent to Hong Kong where she became the harbour defence ship. Wivern became a distilling ship in 1898 and was sold in May 1922 for scrap.
Bibliografia
- Gardiner, Robert, ed. (1979). Conway's All the World's Fighting Ships 1860–1905. Greenwich: Conway Maritime Press. ISBN 0-8317-0302-4.
- Parkes, Oscar (1990). British Battleships (ristampa dell'ed. 1957). Annapolis, Maryland: Naval Institute Press. ISBN 1-55750-075-4.
- Putnam, Arnold A. (1999). "The Building of Numbers 294 & 295: The Laird Rams". In Preston, Antony. Warship 1999–2000. Londra: Conway Maritime Press. ISBN 0-85177-724-4.
- Scharf, J. Thomas (1977). History of the Confederate States Navy: From its Organization to the Surrender of its Last Vessel. New York: Fairfax Press. ISBN 0-517-23913-2. OCLC 4361326.
- Sullivan, David M. (1987). "Phantom Fleet: The Confederacy's Unclaimed European Warships". Warship International. Toledo, OH: International Naval Research Organization. XXIV (1): 12–32. ISSN 0043-0374.