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Advanced SEAL Delivery System (ASDS)

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Background and Overview

The U.S. Navy SEALs have long made use of "wet" submersibles (SEAL Delivery Vehicles, or SDVs) for their medium-range undersea transportation. And while the SDVs have served the Naval Special Warfare community with distinction, they have long suffered from one consistent drawback: all embarked members had to endure extended periods of time in frigid ocean waters with only a wet or dry suit to protect them from the elements (and no, just because it's a "dry" suit doesn't mean it's a "warm" suit). And while this factor, in and of itself, may not seem to be of great concern, experience has shown that human body performance degrades on a predictable scale in relation to the time spend in a given temperature. This has little consequence for the average person, however for a commando who is expected to perform at an exceptionally high level for an unknown period of time in a potentially dangerous environment, the stakes are much, much higher.

Essential to Naval Special Warfare is the ability to conduct clandestine insertions and extractions of SEAL squads into high threat environments.  The Advanced SEAL Delivery System does just that.  Transportable by C-5 and C-17 aircraft, the ASDS is a manned, dry interior, combatant submersible with the requisite range endurance, speed, payload, and other capabilities for operations in a full range of hostile environments.  

The first ASDS system was built in fiscal year 1997 and tested in fiscal year 1998.  The host platform for this battery-powered craft is a fast attack submarine or landing ship dock.  The first 688-class fast attack submarine host platform completed support modification in fiscal year 1997.

The details of the range and speed of the ASDS remain classified, however reports indicate it can travel at approximately 8 knots to a distance of at least 125 miles. The 65-foot ASDS is operated by a pilot drawn from the Submariner community, alongside a SEAL navigator. Behind these crewmen, between eight and sixteen (16) SEALs can be accommodated, depending on how they are equipped. Exit from the ASDS is accomplished through a lock-in/lock-out chamber in the floor of the craft, which has also been manufactured so that it can dock with a parent submarine, much like a deep submergence rescue vehicle.

This craft will be adapted to the next class of U.S. nuclear submarines, the New Attack Submarine (NSSN). Already optimized for use by Naval Special Warfare personnel with increased room for men and gear, the NSSN will also be built with a nine-man lock-out/lock-in chamber for the insertion and recovery of Special Operations Forces. When fitted with an ASDS-capable Dry Deck Shelter (DDS), the NSSN can deliver a significant number of Special Operations Forces and their equipment quickly and quietly while remaining submerged and undetected. The primary delivery vehicle for the Advanced SEAL Delivery System will be launched the Los Angeles (SSN-688), Seawolf (SSN-21) and NSSN Class Submarines.  GREENEVILLE is especially equipped for submarine rescue. Capable of performing the mother submarine role for the Deep Submergence Rescue Vehicle (DSRV), she may fulfill bi-lateral and multi-lateral agreements with allies to assist in the rescue of a downed submarine. GREENEVILLE will become the Pacific test platform for the ASDS. 

Numerous manufacturers have contributed to this project. Alliant Techsystems/Valence Technology has submitted a proposal to replace current zinc-silver oxide batteries in three Navy underwater vehicle applications (MK-30 target, MK-8 SEAL Delivery Vehicle and the Advanced SEAL Delivery System) with commercial lithium ion polymer batteries. These systems procure $5M plus of batteries per year because of finite recharge cycles and wet life requiring their replacement every 12 to 18 months. Lithium ion batteries will provide over 10 times the cycle life of the silver-zinc. Draper Laboratories designed and developed an integrated control and display system, including the primary control system, navigation system, sensors, and displays, and dual-redundant flight control computers and operational software for the ASDS as well. 

ASDS Characteristics

Length: 65 feet

Beam: 6.75 feet

Height: 8.25 feet

Dry Weight: 55 tons

Range: 125+ miles

Speed: 8+ knots

Propulsion: 67 hp electric motor (Ag-Zn battery)

Diving Depth: Classified

Crew: Two (2) (pilot and navigator)

Masts: 2 (Port - periscope, Starboard - Communication + Global Positioning System)

Sonar: Forward Looking - detect natural/man made obstacles
Side Looking - terrain & bottom mapping, mine detection

Passengers: Up to sixteen SEALs, depending on equipment loads

(Note: The above information was derived entirely from open unclassified sources.)

Articles

Article: U.S. Navy tests the Advanced SEAL Delivery System at Pearl Harbor.

Article: Pearl Harbor SEALs introduce more capable delivery vehicle

FAS - SDV and ASDS

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