DSV-5 Nemo

NEMO consisted of a spherical pressure hull with a 61-inch (1.5 m) inside diameter and a 66-inch (1.7 m) outside diameter, plus outside life support and operational subsystems housed below the crew compartment. The hull was made from 2.5-inch (6.4 cm) thick transparent acrylic, Poly(methyl methacrylate), and housed a crew of two (pilot and observer). Operational subsystems included a main lead acid battery power supply, electrical distribution and control circuitry, a hydraulic system to operate a self-contained winch/anchor system, and two side-mounted thrusters for rotation and limited horizontal movement. A compressed air ballast system was used for controlling buoyancy.[5] NEMO was untethered and relied on its own batteries for power.[6] NEMO also carried a radio for communicating with NEMO's mothership, divers, or other submersibles.[7]

NEMO was designed for depths of up to 600 feet (180 m), the depth of the continental shelf, although it was later certified for 1,000-foot (300 m) depths.[5] Its deepest recorded dive was 614 feet (187 m).[2] Its life support system gave it an endurance of 8 hours, though it also had an emergency backup system that could provide up to an additional 24 hours.[5] NEMO weighed 8,000 pounds (3.6 t) and could carry a payload of 450 pounds (200 kg). The side thrusters could propel NEMO at speeds of up to .75 knots (1.39 km/h; 0.86 mph).[7]

NEMO was built alongside two additional hulls by the Southwest Research Institute at Naval Air Station Point Mugu in California, under contract for and in cooperation with the Naval Civil Engineering Laboratory (NCEL), now the Naval Facilities Engineering Command Engineering Service Center.[7] NEMO's mission was to test the feasibility and utility of an all-acrylic spherical hull and then to support underwater construction, repair, and salvage work.[5][7] Its other two hulls were used for fatigue and collapse testing, which found a crush depth of 4,150 feet (1,260 m).[5] NCEL evaluated NEMO in the Bahamas between 1970 and 1972, performing over 100 dives. The evaluation concluded that NEMO was an effective, comfortable, safe, and reliable underwater observation platform, although its usefulness was hindered by the lack of a hovering capability.[5] Following its evaluation, NEMO was used by the Navy Seabees to observe and monitor undersea construction.[2] NEMO provided a shirt-sleeve environment for nondiving engineers, technicians, and scientists to oversee undersea construction, allowing them to see and communicate with divers for the first time.[7] It played an important role in undersea cable laying and maintenance.[1] NEMO made several hundred dives off the Bahamas and Channel Islands over the course of its Navy career.[2]

NEMO submerged

NEMO was transferred to "other government agencies" (likely the CIA) on 30 September 1986.[5] Details about its activities since being transferred are obscured.[8] In July 2011, NEMO left government service and was transferred to the U.S. Navy Seabee Museum at Naval Base Ventura County, Port Hueneme, California,[2] where it is still on display.[9]

• Alvin (DSV-1) – A manned deep-ocean research submersible owned by the United States Navy and operated by the Woods Hole Oceanographic Institution

• This article includes information collected from the Naval Vessel Register, which, as a U.S. government publication, is in the public domain. The entry can be found here.

• 1970 technical report describing NEMO's construction in detail