DSV Alvin

Alvin in 1978, a year after first exploring hydrothermal vents. The rack hanging at the bow holds sample containers.
History
United States
Name: Alvin
Namesake: Allyn Vine
Operator: Woods Hole Oceanographic Institution
Builder: Litton Systems
Acquired: 26 May 1964
In service: 5 June 1964
Status: in active service, as of 2017
General characteristics [1]
Type: Deep-submergence vehicle
Tonnage: 17 t (17 long tons)
Length: 7.1 m (23 ft 4 in)
Beam: 2.6 m (8 ft 6 in)
Height: 3.7 m (12 ft 2 in)
Draft: 2.3 m (7 ft 7 in)
Speed: 2 knots (3.7 km/h; 2.3 mph)
Range: 5 km (3.1 mi)
Endurance: 72 hours with 3 crew
Test depth: 6,500 m (21,300 ft)
Capacity: 680 kg (1,500 lb) payload
Crew: 3 (1 pilot, 2 scientific observers)

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 more than 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

Emergency separation
General layout

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 meters (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 m (1 ft 7 in) in diameter and somewhat thicker than the 2-inch (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.

Harold E. Froehlich was one of the principle designers of Alvin.[3]

History

Early career

Alvin, first of its ship class of deep submergence vehicle (DSV), was built to dive to 2,440 meters (8,010 ft). Each of the Alvin-class DSVs have different depth capabilities. However Alvin is the only one seconded to the National Oceanic and Atmospheric Administration (NOAA), with the others staying with the United States Navy.

Alvin's first deep sea tests took place off Andros Island, the Bahamas, where it made a successful 12-hour, unmanned tethered 7,500-foot (2,300 m) test dive. On 20 July 1965 Alvin made its first 6,000-foot (1,800 m) manned dive for the Navy to obtain certification.[2] On 17 March 1966, Alvin was used to locate a submerged 1.45-megaton hydrogen bomb lost in a United States Air Force midair accident over Palomares, Spain. The bomb, found resting nearly 910 m (2,990 ft) deep, was raised intact on 7 April. On 6 July 1967, the Alvin was attacked by a swordfish during dive 202. The swordfish became trapped in the Alvin's skin, and the Alvin was forced to make an emergency surface. The attack took place at 2,000 feet (610 m) below the surface. The fish was recovered at the surface and cooked for dinner.[2] During Dive 209, on 24 September 1968 Alvin found an F6F Hellcat, #42782, 125 miles southeast of Nantucket.[4] The aircraft had ditched 30 September 1944 during carrier qualifications; the pilot survived.[5]

Sinking

The sunken Alvin on the ocean bottom in June 1969, photographed by USNS Mizar (T-AGOR-11).

Alvin, aboard the Navy tender ship Lulu, was lost as it was being transported on 16 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 m (4,900 ft) of water in the Atlantic Ocean at approximately 39°53′30″N 069°15′30″W / 39.89167°N 69.25833°W / 39.89167; -69.25833 ("DSV Alvin"), about 88 nautical miles (101 miles; 163 km) south of Nantucket Island.[6]

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, a DSV built by Reynolds Metals 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 August 27, 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.[6]

Post-sinking career

In 1973, Alvin's pressure hull was replaced by a newer titanium pressure hull. The new hull extended the submersible's depth rating.

Black smokers

In 1977, during an expedition led by Robert Ballard and sponsored by the National Oceanic and Atmospheric Administration (NOAA), Alvin discovered and documented the existence of black smokers around the Galapagos Islands. Existing at a depth of more than 2,000 m (6,600 ft), black smokers emit a strong flow of black, smoky water, superheated to over 400 °C (752 °F). Alvin was able to sample the water from a black smoker. Alvin discovered that the pH was roughly 2.8 (strongly acidic).

Exploration of RMS Titanic

Most famously, Alvin was involved in the exploration of the wreckage of RMS Titanic in 1986. Launched from her support ship RV Atlantis II, she carried Dr. Robert Ballard and two companions to the wreckage of the great liner. Titanic sank in 1912 after striking an iceberg while crossing the North Atlantic Ocean on her maiden voyage.

Alvin, accompanied by a small remotely operated vehicle (ROV) named Jason Jr., was able to conduct detailed photographic surveys and inspections of Titanic's wreckage. Many of the photographs of the expedition have been published in the magazine of the National Geographic Society which was a major sponsor of the expedition.

The Woods Hole Oceanographic Institution team involved in the Titanic expedition also explored the wreck of the USS Scorpion (SSN-589), a Skipjack-class submarine armed with nuclear torpedoes, which sank off the coast of the Azores in 1968 in uncertain circumstances. Alvin obtained photographic and other environmental monitoring data from the remains of Scorpion.

Recent overhauls

Alvin during refit of the personnel sphere

Over the years, Alvin has undergone many overhauls to improve its equipment and extend its lifetime. In 2001, among other equipment, motor controllers and computer systems were added. The current Alvin is the same as the original vessel in name and general design only. All components of the vessel, including the frame and personnel sphere, have been replaced at least once. Alvin is completely disassembled every three to five years for a complete inspection.[7] A new robotic arm was added in 2006.

Current work

In June 2008 construction started on a stronger and slightly larger personnel sphere which may be used to upgrade Alvin (for use from 2011), before being used in an entirely new vehicle.[8] The new sphere was designed, and then forged, from solid titanium ingots, in two equal halves, at Ladish Forge, Cudahy, Wisconsin, and then the 15.5 tonnes of titanium was machined and assembled, utilizing five view ports (instead of the current three) and is designed for depths of over 6,000 m (20,000 ft), where Alvin's constructed depth limit was 4,500 m (14,800 ft).[9] This, along with a general upgrade of support systems, instruments and materials, will allow Alvin to reach 98% of the ocean floor.[10] After one last dive to assess damage to the Gulf of Mexico's seafloor after the Deepwater Horizon disaster, Alvin will be refitted starting January 2011, with an expected return to the ocean in 2012 and full depth potential achieved in 2015.[11]

2014 overhaul

In early 2014, an extensively refitted Alvin started verification testing in the Gulf of Mexico. Featuring new cameras, lighting, and a larger titanium personnel sphere, this new Alvin is the result of a three-and-a-half year effort to bring the sub to new depths.[12] In March and April 2014, Alvin was used to explore the site of the 2010 Deepwater Horizon oil spill.[13]

Operation

Alvin uses four 208-pound (94 kg) steel weights (~1.7 cubic feet of steel) to provide negative buoyancy for the trip to the ocean floor. Alvin contains a ballast and trim system, but the steel weights allow deep dives to be achieved more rapidly. These weights are jettisoned on each dive and left at the bottom.[14][15]

The DSV Alvin on the fantail (stern) of the R/V Atlantis following a dive. On the right side of the photograph the A-frame crane can be seen that lowers Alvin into the water and on the left, Alvin's hangar.

See also

Alvin-class DSV

Other deep submergence vehicles

Notes

  1. 1 2 "Alvin Specifications". Woods Hole Oceanographic Institution. 2012. Retrieved 5 August 2012.
  2. 1 2 3 "History of Alvin". Woods Hole Oceanographic Institution. 2012. Retrieved 5 August 2012.
  3. ↑ Pearce, Jeremy (May 26, 2007). "Harold Froehlich, 84, Dies; Designed Deep-Sea Minisub". The New York Times. Retrieved March 17, 2017.
  4. ↑ 12:00 High
  5. ↑ History of Alvin
  6. 1 2 Anonymous, SALVOPS 69, Washington, D.C.:Department of the Navy Naval Ship Systes Command, 1969, pp. 1-18.
  7. ↑ "Human Occupied Vehicle Alvin". Woods Hole Oceanographic Institution. 2012. Retrieved 5 August 2012.
  8. ↑ Broad, William J. (26 August 2008). "Forging a new sphere". The New York Times. p. F1.
  9. ↑ Borel, Brooke, "Alvin Redux", Popular Science, March 2013
  10. ↑ Hsu, Jeremy (16 December 2010). "Upgraded Sub Could Reach 98 Percent of Ocean Deep". OurAmazingPlanet.com. Retrieved 5 August 2012.
  11. ↑ Amos, Jonathan (16 December 2010). "Ocean science giant Alvin set for upgrade". BBC News. Retrieved 5 August 2012.
  12. ↑ Lippsett, Lonny (13 March 2014). "Not Your Grandfather's Cadillac". Woods Hole Oceanographic Institution. Retrieved 18 March 2014.
  13. ↑ Juhasz, Antonia (2014-04-01), "The Deepwater Horizon Spill, Four Years On", Harper's
  14. ↑ deGruy, Mike (18 November 1999). "Marine Advanced Technology Education (MATE) Center – Expedition Log". marinetech.org. Archived from the original on 20 July 2012. Retrieved 5 August 2012.
  15. ↑ Nevala, Amy E. (3 August 2005). "Alvin's Pilots". Oceanus. Retrieved 5 August 2012.

References

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