DSV Alvin

Alvin (DSV-2) is a manned deep-ocean research submersible owned by the United States Navy and operated by the Woods Hole Oceanographic Institution (WHOI) in Woods Hole, Massachusetts. The vehicle was built by General Mills' Electronics Group[2] in Minneapolis, Minnesota. Named to honor the prime mover and creative inspiration for the vehicle, Allyn Vine, Alvin was commissioned on 5 June 1964. The submersible is launched from the deep submergence support vessel RV Atlantis (AGOR-25), which is also owned by the U.S. Navy and operated by WHOI. The submersible has made over 4,400 dives, carrying two scientists and a pilot, to observe the lifeforms that must cope with super-pressures and move about in total darkness, as well as exploring the wreck of Titanic. Research conducted by Alvin has been featured in nearly 2,000 scientific papers.

Design

Alvin was designed as a replacement for bathyscaphes and other less maneuverable oceanographic vehicles. Its more nimble design was made possible in part by the development of syntactic foam, which is buoyant and yet strong enough to serve as a structural material at great depths. The vessel weighs 17 tons. It allows for two scientists and one pilot to dive for up to nine hours at 4,500 metres (14,800 ft). The submersible features two robotic arms and can be fitted with mission-specific sampling and experimental gear. The plug hatch of the vessel is 0.48 metres (1 ft 7 in) in diameter and somewhat thicker than the 2 inches (51 mm) thick titanium sphere pressure hull;[1] it is held in place by the pressure of the water above it. In an emergency, if Alvin were stuck underwater with occupants inside, the outer body, or cladding, of the submersible could be released and discarded using controls inside the hull. The titanium sphere would then rise to the surface uncontrolled. It is unknown, however, if a human could survive the rapid trip to the surface.

Alvin, aboard the Navy tender ship Lulu, was lost as it was being transported in October 1968. Lulu, a vessel created from a pair of decommissioned U.S. Navy pontoon boats with a support structure added on, was lowering Alvin over the side when two steel cables snapped. There were three crew members aboard Alvin at the time, and the hatch was open. Situated between the pontoons with no deck underneath, Alvin hit the water and rapidly began to sink. The three crew members managed to escape, but Alvin flooded and sank in 1,500 metres (4,900 ft) of water.[5] Severe weather prevented the recovery of Alvin throughout late 1968, but it was photographed on the bottom in June 1969 by a sled towed by USS Mizar. Alvin was found to be upright and appeared intact except for damage to the stern. It was decided to attempt recovery; although no object of Alvin's size had ever been recovered from a depth of 5,000 feet (1,500 m), recovery was "deemed to be within the state of the art". In August 1969, the Aluminaut, another DSV built by Reynolds Metals Aluminum Company, descended to Alvin but had trouble attaching the required lines, and side effects from Hurricane Camille were producing worsening weather, causing the team to return to Woods Hole to regroup. The second attempt started on 27 August, and Aluminaut was able to secure a line and safety slings on Alvin, and wrapped a prefabricated nylon net around its hull, allowing it to be hauled up by Mizar. Alvin was towed, submerged at 40 feet (12 m), at a speed of 2 knots (3.7 km/h), back to Woods Hole.