SUBSIM Radio Room Forums - Dry Combat Submersible vs wet SDV's coming soon

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For decades, the U.S. Navy SEALs have primarily used “wet” SEAL Delivery Vehicles (SDV) midget submarines where the passenger compartment is flooded to the temperatures and operational environmental conditions of the waters outside and the riders have to wear SCBA masks for breathing. To address SOCOM’s emphasis on BioTechnology and special forces Operators’ overall health and well-being, having a submersible with a pressurized dry interior allows for better Operator endurance, especially, for example, in the colder waters such as the Arctic.

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Torpedo-shaped, the DCS should keep SEALs dry during transit, bolstering their endurance and readiness rate before they reach the DCS’s transit objective area and emerge out of the DCS to deploy “wet” by swimming to the target area. Obviously, many details of the United Kingdom’s MSubs Ltd™ (Marlin Submarines LtdM) designed and manufactured S351 “Nemesis,” which SOCOM DCSs are based off of, are classified; however some open source information can be ascertained.

S351 “Nemesis” Specifications (which the USSOCOM DCS is based off of):
• Length: 12 meters (39 feet). Height: 2.4 meters (7.9 feet)
• Weight: 14 tons (31,000 lbs) fully loaded
• Displacement: 28 tons (62,000 lbs)
• Shipping size: Transportable in a 40-foot shipping container
• Crew: two–a pilot and a co-pilot/navigator
• Passengers: Eight fully-equipped SEALs

• Interior Environment: All pressurized “dry” (not flooded “wet”) with three sections: forward compartment transport for SEAL passengers, amidships swimmer Lock-in/Loc-out trunk, and aft command section for pilot and co-pilot. (USSOCOM declined comment on if the interiors are lighted and heated).
• Performance:
o Diving depth: 100 meters (330 feet)
o Range: 60 nautical miles (110 KM, 69 miles) with Lithium-ion (longer with aluminum-seawater)
o Speed: 5 knots (9.3 KM/Hr, 5.8 MPH). Maximum speed: Classified
o Endurance: greater than 24 hours (Classified range with aluminum-saltwater batteries (USSOCOM specific))
▪ Triple the range of SEAL Delivery Vehicle and twice that of Shallow Water Combat Submersible (potential of up to ten times the range with aluminum-saltwater batteries)
• Sensors:
o Inertial navigation and Doppler Velocity Log
o Sonar and fathometer
o Underwater telephone and UHF radio
o Two sensor masts
o Terrain-Following/Terrain-Avoidance sonar (USSOCOM specific)
o Radio Frequencies Countermeasures sensor and library (USSOCOM specific)

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According to officials at vSOFIC, additional USSOCOM-specific sensors include Terrain-following, Terrain-avoidance sonar capability (useful for hugging coastal cliffs, islands, and continental shelfs), low acoustic and thermal signature, and “Radio Frequency countermeasures” which officials defined as an onboard computer possessing a library of threat radar signatures that the DCS can identify and track according to radar band, position, and type. Such RF countermeasures would be very helpful when penetrating a coastline undetected and for avoiding surface water search radars.