HMS Captain

1870

Biscay squall, the designer aboard, five minutes Location: Bay of Biscay, off Cape Finisterre · Coordinates: 43.50°N 10.50°W · Casualties: 482 · Survivors: 18 · Depth: 600 m (approximate) · Cause: capsized · design flaw — Capsized in a squall in the Bay of Biscay in the early hours of 7 September 1870. Her low freeboard and the combined weight of her heavy masts, rigging, and gun turrets left her dynamically unstable beyond modest angles of heel. She rolled over and sank in under five minutes. · Fate: abyssal · not located · Type: warship · turret ironclad · Tonnage: 7,767 tons · Crew: 500 · Flag: United Kingdom · Launched: 1869 Royal Navy experimental turret ship, designed by Captain Cowper Coles against the warnings of the Admiralty's constructors; her freeboard was too low and her top-hamper too heavy. In a Biscay squall on 7 September 1870 she capsized in under five minutes. 482 dead, including Coles himself. The scandal reshaped how the Royal Navy reviewed warship design for a generation. The Vessel HMS Captain was a British ironclad turret ship of the Royal Navy, built at the Cammell Laird yard at Birkenhead between 1867 and 1870 and commissioned on 30 April 1870. She was 97 metres long, 7,767 tons displacement, and powered by twin-screw 900-horsepower compound steam engines; she was additionally rigged as a full three-masted barque with a total sail area of approximately 3,625 square metres. Her armament comprised four 12-inch muzzle-loading rifled guns mounted in two twin-gun turrets on her main deck, plus two 7-inch muzzle-loading rifled guns on the upper deck as auxiliary armament. Her design was a specific project of Captain Cowper Phipps Coles, Royal Navy, the principal British advocate of the turret ship concept. Coles had publicly argued since 1859 that the future of naval architecture was the combination of steam propulsion, iron armour, and rotating gun turrets, and he had persistently criticised the Royal Navy's existing ironclad designs as insufficiently revolutionary. His specific vision for HMS Captain was a ship combining turret armament with full sailing rig, thus providing both the tactical capabilities of a modern turret ship and the strategic range of a sailing vessel. The design was substantially controversial within the Royal Navy. The Admiralty's Chief Constructor, Sir Edward Reed, had persistently opposed the Captain design on the technical grounds that the combination of turret armament (which required a low freeboard to minimise target profile) The Disaster At approximately 00:15 on 7 September 1870, HMS Captain was hit by a gust of wind approximately 10 kilometres per hour above the ambient force 7 wind speed. The ship, sailing under single-reefed topsails, heeled to approximately 18 degrees under the gust pressure. The 18-degree heel was catastrophic for Captain's marginal stability. Her design had been calculated for a maximum stable heel angle of approximately 20 degrees; the subsequent stability calculations, prepared after the loss by Sir Edward Reed for the Admiralty inquiry, established that her actual maximum stable heel angle was approximately 14 degrees due to discrepancies between the design specifications and the as-built ship. At 18 degrees heel, Captain was beyond the point of recoverable stability. The ship's lee main deck submerged. Water flooded into her deck hatches, which had been left partially open for ventilation during the watch. Her heel progressed rapidly from 18 to approximately 25 degrees, at which point the water pouring into her lee side exceeded any residual righting moment. HMS Captain capsized at approximately 00:20 on 7 September 1870 in approximately 1,200 metres of water off Cape Finisterre. The capsize was catastrophic and rapid: the ship rolled completely upside down within approximately 30 seconds of the loss of stability. Her four turret guns, which weighed approximately 92 tonnes combined, fell through her inverted structure as she rolled, causing substantial structural damage that accele