DSV-4 (formerly known asSea Cliff) is a 25-ton, crewed deep-ocean research submersible owned by theUnited States Navy, now known only by itshull number, not by its former name.
DSV-4 is anAlvin-classdeep submergence vehicle (DSV), asister ship toTurtle (DSV-3) andAlvin (DSV-2). TheAlvin-class DSVs were designed to replace older DSVs, such as the less-maneuverableTrieste-classbathyscaphes.Sea Cliff was built byElectric Boat in Groton, Connecticut for the U.S. Navy and was completed in December 1968. It spent much of its service life on loan to theWoods Hole Oceanographic Institution.
DSV-4 initially had a maximum dive depth of 6,500 feet (2,000 m); allAlvin-class personnel pressure hulls were originally designed for 6,000 ft (1,800 m), but subsequent testing allowed a higher rating. In 1981, the submersible was refitted with a titanium personnel hull to dive to 20,000 ft (6,100 m).[1] With the refit of DSV-4, the bathyscaphe DSV-1 (formerly known asTrieste II) was retired from service.
In 1985 the Sea Cliff made a record dive for this vessel type by diving 20,000 feet off Guatemala's Pacific Coast.[2] The crew of the dive consisted of NAVSEA system certification representative/command pilot, LCDR Rick Williams, mission pilot Lt. Alan Mason, and co-pilot Chief Petty Officer David Atchinson. From late September to early October 1990, over a course of 6 days, DSV-4 recovered the cargo door ofUnited Airlines Flight 811 from thePacific Ocean.
DSV-4 has aplug hatch 2 feet (0.61 m) in diameter, held in place mechanically with hatch dogs and, while submerged, by the pressure of the water above it.
Sea Cliff was retired from active service in 1998 and subsequently given toWoods Hole Oceanographic Institution (WHOI).[3] As of 2019, theNaval Vessel Register shows DSV-4 was returned to active U.S. Navy service on September 30, 2002, in the custody of Woods Hole.[4]
Although an article inThe New York Times from 1998 indicated that DSV-4 would be cannibalized to upgradeAlvin,[5] this appears to not have taken place since: 1) the US Navy Vessel Registry shows DSV-4 as an active vessel; 2) a photo from 2005 shows DSV-4 to still be intact with its personnel pressure sphere;[6] and 3) WHOI in its official history of Alvin does not discuss using DSV-4 parts during this timeframe.[7] As of September 2023, WHOI does not list DSV-4 as one of their underwater vehicles.[8]
This article incorporatespublic domain material fromNo Name (DSV-4) at theNaval Vessel Register.
