The SEAL Delivery Vehicle (SDV) is a crewed
submersible and a type of
swimmer delivery vehicle used to deliver
United States Navy SEALs and their equipment for
special operations
Special operations (S.O.) are military activities conducted, according to NATO, by "specially designated, organized, selected, trained, and equipped forces using unconventional techniques and modes of employment". Special operations may include ...
missions. It is also operated by the
Royal Navy
The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against F ...
's
Special Boat Service
The Special Boat Service (SBS) is the special forces unit of the United Kingdom's Royal Navy. The SBS can trace its origins back to the Second World War when the Army Special Boat Section was formed in 1940. After the Second World War, the Roya ...
, which operates three SDVs.
The SDV, which has been in continuous service since 1983, is used primarily for covert or clandestine missions to denied access areas (either held by hostile forces or where military activity would draw notice and objection). It is generally deployed from the
Dry Deck Shelter
A dry deck shelter (DDS) is a removable module that can be attached to a submarine to allow divers easy exit and entrance while the boat is submerged. The host submarine must be specially modified to accommodate the DDS, with the appropriate mating ...
on a specially-modified
attack or
ballistic missile submarines, although it can also be launched from surface ships or land. It has seen combat in the
Gulf War
The Gulf War was a 1990–1991 armed campaign waged by a Coalition of the Gulf War, 35-country military coalition in response to the Iraqi invasion of Kuwait. Spearheaded by the United States, the coalition's efforts against Ba'athist Iraq, ...
,
Iraq War
{{Infobox military conflict
, conflict = Iraq War {{Nobold, {{lang, ar, حرب العراق (Arabic) {{Nobold, {{lang, ku, شەڕی عێراق (Kurdish languages, Kurdish)
, partof = the Iraq conflict (2003–present), I ...
, and the
US intervention in Somalia.
The SDV was intended to be replaced with the
Advanced SEAL Delivery System (ASDS), a larger, dry submersible that is often confused with the SDV. The SDV is
flooded, and the swimmers ride exposed to the water, breathing from the vehicle's compressed air supply or using their own SCUBA gear, while the ASDS is dry inside and equipped with a full life support and air conditioning system. The ASDS was canceled in 2009 due to cost overruns and the loss of the prototype in a fire.
The Navy currently plans to replace the SDV with the
Shallow Water Combat Submersible
The Shallow Water Combat Submersible (SWCS) is a manned submersible and a type of swimmer delivery vehicle that is planned to be used to deliver United States Navy SEALs and their equipment for special operations missions. It will replace the cu ...
(SWCS), which will be designated the Mark 11 SDV.
The SWCS is expected to enter service in 2019.
History
The SDV program dates back to
World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
. Initiated by the
Office of Strategic Services Maritime Unit (OSS MU). A “submersible canoe” was invented by the Italians during World War I. The idea was successfully applied by the Italian Navy (''
Regia Marina
The ''Regia Marina'' (; ) was the navy of the Kingdom of Italy (''Regno d'Italia'') from 1861 to 1946. In 1946, with the Italian constitutional referendum, 1946, birth of the Italian Republic (''Repubblica Italiana''), the ''Regia Marina'' ch ...
'') also early in World War II. The official Italian name for their craft was ''Siluro a Lenta Corsa'' (SLC or "
Slow-running torpedo"). The vehicle was then copied by the British when they discovered the Italian operations and called it the "
Sleeping Beauty
''Sleeping Beauty'' (french: La belle au bois dormant, or ''The Beauty in the Sleeping Forest''; german: Dornröschen, or ''Little Briar Rose''), also titled in English as ''The Sleeping Beauty in the Woods'', is a fairy tale about a princess cu ...
" or Motorised Submersible Canoe. It was employed by OSS MU during extensive training and exercises, but was never actually deployed for combat operations.
The same capability was adopted by the American
Underwater Demolition Team
Underwater Demolition Teams (UDT), or frogmen, were amphibious units created by the United States Navy during World War II with specialized non-tactical missions. They were predecessors of the navy's current SEAL teams.
Their primary WWII fun ...
s (UDTs) in 1947. The one-man submersible displayed little functional military potential. However, it substantiated and characterized the need for improved and expanded UDT capabilities.
After the war, development continued in a garage-shop fashion by various UDT units, and included various "Marks" such as the Mark V, VI, and VII. Intermediate numbers were assigned to some vehicles that never made it off the shop floor. All were of flooded design.
[Introduction to Naval Special Warfare](_blank)
''Navy SEALs''. San Diego: Commander, Naval Special Warfare Command
The first SDV to be operationally deployed was the Mark VII, which entered service in June 1972 after being tested between 1967 and 1972.
It could carry three SEALs plus a pilot sitting in compartments fore and aft. It had a hull made from fiberglass and non-ferrous metals to hinder detection and was powered by a
silver-zinc battery
A silver zinc battery is a secondary cell that utilizes silver(I,III) oxide and zinc.
Overview
Silver zinc cells share most of the characteristics of the silver-oxide battery, and in addition, is able to deliver one of the highest specific energi ...
attached to an electric motor.
The Mark VIII SDV, the model that is still in use today, began to supplant the Mark VII starting in 1983.
The wet vehicle SDV program (officially named the Swimmer Delivery Vehicle, later re-designated the SEAL Delivery Vehicle after the Swimmer Delivery Vehicle Teams were renamed
SEAL Delivery Vehicle Teams) currently centers on the Mark VIII Mod 1. The SDV was first developed in 1975 for use among UDT/SEAL teams. The early Mark 8 Mod 0 SDVs had a PRC104
UHF radio for use underwater. The newer model Mark 8 Mod 1 has a dual sliding canopy and quick release hatch.
Design
SDVs carry a pilot, co-pilot, and four person combat swimmer team and their equipment to and from maritime mission objectives on land or at sea. The pilot and co-pilot are often a part of the fighting team. The SDV is
silver-zinc battery
A silver zinc battery is a secondary cell that utilizes silver(I,III) oxide and zinc.
Overview
Silver zinc cells share most of the characteristics of the silver-oxide battery, and in addition, is able to deliver one of the highest specific energi ...
powered and equipped with propulsion, navigation, communication, and life-support equipment.
The batteries directly power the electric motor that drives the single screw propeller.
Because they are all electric, SDVs are extremely difficult to detect using passive sonar, and their small size makes them hard to detect using other means.
The Mark 8 Mod 1 SDV can deliver four fully equipped SEALs to the mission area, be "parked" or loiter in the area, retrieve the SEALs, and then return to the launch site. The SEALs sit upright in the Mark 8, with the pilot and co-pilot/navigator facing forward and the other four facing aft.
For air, the SEALs rely on their own
air tanks or
rebreather
A rebreather is a breathing apparatus that absorbs the carbon dioxide of a user's breathing, exhaled breath to permit the rebreathing (recycling) of the substantially unused oxygen content, and unused inert content when present, of each breath. ...
s, supplemented by compressed air tanks on the SDV. The crew and passenger compartment in the Mark 8 is small, cramped, and pitch black except for the dim lights of the instrument panel;
SEALs describe riding in an SDV as like "being locked in a little black coffin deep under the water."
A 2011 article reported that out of 2,600 SEALS roughly 230 are trained to operate the SDVs.
SDVs are generally launched from a
Dry Deck Shelter
A dry deck shelter (DDS) is a removable module that can be attached to a submarine to allow divers easy exit and entrance while the boat is submerged. The host submarine must be specially modified to accommodate the DDS, with the appropriate mating ...
on the back of a
submarine
A submarine (or sub) is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. The term is also sometimes used historically or colloquially to refer to remotely op ...
, although they can also be deployed from
amphibious carriers and other surface ships equipped to launch and recover the SDV. SDVs are launched and recovered by surface ships using a crane.
They can also be
airdrop
An airdrop is a type of airlift in which items including weapons, equipment, humanitarian aid or leaflets are delivered by military or civilian aircraft without their landing. Developed during World War II to resupply otherwise inaccessible tr ...
ped (uncrewed) into an operational area from a
C-130 Hercules airplane.
Finally, the SDV can be launched from the shore.
An SDV can be launched from one platform and recovered by another. demonstrated this capability during a multilateral exercise in the
Mediterranean
The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western Europe, Western and Southern Europe and Anatolia, on the south by North Africa ...
when it recovered and then launched another country's SDV.
Mark 8 SDV
The Mark 8 Mod 1 SDV is the only SDV officially in use by the US Navy and Royal Navy. It is an upgrade of the earlier Mark 8 Mod 0 SDV. The Mod 1 is quieter, faster, more efficient, and has a longer range than the Mod 0.
Its updated electronics, materials, and battery and motor systems gives it twice the range and 1.5 times the speed of the Mod 0.
Another advantage of the Mark 8 Mod 1 over its predecessor is that it is built from aluminium instead of plastic reinforced fiberglass, making its hull sturdier and roomier.
The sturdier hull means that it can be deployed from
CH-46 Sea Knight
The Boeing Vertol CH-46 Sea Knight is a medium-lift tandem-rotor transport helicopter powered by twin turboshaft engines. It was designed by Vertol and manufactured by Boeing Vertol following Vertol's acquisition by Boeing.
Development of ...
and
CH-53E Super Stallion
The Sikorsky CH-53E Super Stallion is a heavy-lift helicopter operated by the United States military. As the Sikorsky S-80, it was developed from the CH-53 Sea Stallion, mainly by adding a third engine, adding a seventh blade to the main rotor, ...
helicopters, although SDVs often break or explode when dropped in the water from a helicopter, making aerial deployments impractical and undesirable.
The Mark 8 Mod 1 SDV has an endurance of about eight to 12 hours,
giving it a range of with a diving team or without.
The main limiting factor on endurance is not batteries or breathing gas for the SEALs, but water temperature:
humans can only spend so much time in cold water, even with
wetsuit
A wetsuit is a garment worn to provide thermal protection while wet. It is usually made of foamed neoprene, and is worn by surfers, divers, windsurfers, canoeists, and others engaged in water sports and other activities in or on water. It ...
s, before their blood pressure drops and they become dehydrated from losing blood volume and body fluids, respectively.
Mark 9 SDV
Despite being a development of the Mark 8 SDV, the Mark 9 is a very different vehicle, designed for attacking surface ships rather than deploying SEAL teams on clandestine operations. Indeed, the Mark 9 and Mark 8 share very few common parts.
The Mark 9 carries two SEALs, a pilot and a navigator, and two
Mark 31 or
Mark 37 torpedo
The Mark 37 torpedo is a torpedo with electrical propulsion, developed for the US Navy after World War II. It entered service with the US Navy in the early 1950s, with over 3,300 produced. It was phased out of service key with the US Navy during ...
es for standoff attacks against ships.
These torpedoes can travel up to in a straight line,
carry a warhead, and are capable of sinking ships as large as
cruisers.
In addition to torpedoes, the Mark 9 also carried
limpet mines and satchel charges in a large cargo compartment aft of the pilot and co-pilot.
The Mark 9 is designed to clandestinely approach enemy vessels while submerged, surface to fire torpedoes, and then escape unnoticed. As such, its design incorporates
stealth characteristics, including a lower profile and sonar absorbing materials.
The Mark 9 SDV was intended to attack ships in shallow coastal waters that full-size submarines could not enter,
and to draw attention of an enemy fleet away from the Mark 9's parent submarine.
Though it proved very effective in exercises, the Mark 9 was retired starting in 1989 and was fully phased out of service by the mid-1990s due to manpower and budget constraints and because all of its capabilities save launching torpedoes were duplicated by the Mark 8.
The pilot and navigator operate the vehicle from a prone position and lay side by side. The prone position gave the Mark 9 a low profile and enabled it to operate in very shallow water,
although SEALs reported that staying prone for the entire duration of an operation was uncomfortable.
The Mark 9's sleek profile and independent
diving planes enabled it to be especially agile.
It was also faster than the Mark 8, reaching speeds of , owing to its twin
screw propeller
A propeller (colloquially often called a screw if on a ship or an airscrew if on an aircraft) is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral which, when rotated, exerts linear thrust upon ...
s and high-performance
silver-zinc batteries
A silver zinc battery is a secondary cell that utilizes silver(I,III) oxide and zinc.
Overview
Silver zinc cells share most of the characteristics of the silver-oxide battery, and in addition, is able to deliver one of the highest specific ener ...
.
Its speed and agility led operators to compare it to flying a fighter jet or driving a sports car.
Operational history
The SDV is used primarily for inserting SEALs for covert operations or for placing mines on ships. It is also used for underwater mapping and terrain exploration, location and recovery of lost or downed objects, and reconnaissance missions.
It has been invaluable at deploying SEAL teams in clandestine missions, as it has enabled them to land on shores inaccessible to a larger submarine with a degree of stealth greater than that offered by small surface craft, helicopters, or other means.
In exercises, the SDV has been found to excel at anti-shipping attacks, being able to attack targets in heavily-guarded fleets or docked at military bases and then slip away undetected. Additionally, it can carry larger
limpet mines than those carried by a diver and has a much greater range than a diver, enabling attacks on larger and more distant enemy ships.
However, the SDV is not without its weaknesses, namely its range, reliability, and mobility. The SDV's short range, which is contingent on
sea state
In oceanography, sea state is the general condition of the free surface on a large body of water—with respect to wind waves and swell—at a certain location and moment. A sea state is characterized by statistics, including the wave height, ...
, water temperature, payload, and other factors, sometimes hinders operations. In one example, the Navy wanted to use an SDV to get a closer look at a Soviet ship anchored in a
Cuba
Cuba ( , ), officially the Republic of Cuba ( es, República de Cuba, links=no ), is an island country comprising the island of Cuba, as well as Isla de la Juventud and several minor archipelagos. Cuba is located where the northern Caribbea ...
n harbor upriver from the
Caribbean Sea
The Caribbean Sea ( es, Mar Caribe; french: Mer des Caraïbes; ht, Lanmè Karayib; jam, Kiaribiyan Sii; nl, Caraïbische Zee; pap, Laman Karibe) is a sea of the Atlantic Ocean in the tropics of the Western Hemisphere. It is bounded by Mexico ...
. The SDV could not have made the round trip to the Soviet vessel from an American ship outside of Cuba's territorial waters, so the mission had to be called off.
Mark 8 SDVs saw combat during the
First Gulf War, where they performed mine reconnaissance and demolition missions.
In the
Iraq War
{{Infobox military conflict
, conflict = Iraq War {{Nobold, {{lang, ar, حرب العراق (Arabic) {{Nobold, {{lang, ku, شەڕی عێراق (Kurdish languages, Kurdish)
, partof = the Iraq conflict (2003–present), I ...
, Mark 8 SDVs were used to secure offshore oil and gas terminals.
Several days before the beginning of the
2003 invasion of Iraq
The 2003 invasion of Iraq was a United States-led invasion of the Republic of Iraq and the first stage of the Iraq War. The invasion phase began on 19 March 2003 (air) and 20 March 2003 (ground) and lasted just over one month, including 26 ...
, two SDV teams were launched from
Mark V Special Operations Craft
The Mark V SOC (Special Operations Craft) was a marine security, patrol, and special forces insertion boat used by the United States Navy and manufactured by VT Halter Marine Inc (Gulfport, Mississippi). It was introduced into service with the ...
in the Persian Gulf. Their objectives were the
hydrographic reconnaissance of the
Al Basrah (MABOT) and Khawr Al Amaya (KAAOT) Oil Terminals. After swimming under the terminals and securing their Mark 8 Mod 1s, the SDV SEALs spent several hours taking pictures and surveying Iraqi activity on both platforms before returning to their boats. On March 20, 2003, SEALs from
SEAL Team 8
The United States Navy Sea, Air, and Land (SEAL) Teams, commonly known as Navy SEALs, are the U.S. Navy's primary special operations force and a component of the Naval Special Warfare Command. Among the SEALs' main functions are conducting sm ...
and
10 (31 SEALs, 2
Navy EOD
United States Navy Explosive Ordnance Disposal technicians render safe all types of ordnance, including improvised, chemical, biological, and nuclear. They perform land and underwater location, identification, render-safe, and recovery (or dispo ...
, 1 USAF combat controller, and several Iraqi interpreters) moved to seize the MABOT oil terminal and KAAOT Oil Terminals, in part using SDVs. The terminals were quickly seized with no casualties, and explosives which were found on the terminals were made safe by Polish
GROM
Grom may refer to:
Military
* JW GROM, a Polish special forces unit
* ORP ''Grom'', several ships of the Polish Navy
* Grom (missile), a Polish anti-aircraft missile
* A Yugoslav/Serbian version of the Kh-23 (AS-9 'Kyle') air-to-surface missi ...
operators.
In 2003, SEALs using SEAL Delivery Vehicles swam ashore along the
Somali coastline and emplaced covert surveillance cameras. Known as cardinals, the cameras were designed to watch likely target locations for wanted terrorists as
al-Qaeda
Al-Qaeda (; , ) is an Islamic extremism, Islamic extremist organization composed of Salafist jihadists. Its members are mostly composed of Arab, Arabs, but also include other peoples. Al-Qaeda has mounted attacks on civilian and military ta ...
and its affiliates began to regroup in the country, however the cameras only took one image a day and captured very little.
In American service, the SDV is deployed with
SEAL Delivery Vehicle Team 1
Naval Special Warfare Group 3 (NSWG-3), based at the Naval Amphibious Base Coronado in California, was one of six constituent formations of the United States Naval Special Warfare Command. Until 2008, NSWG-3 was composed of two SEAL Delivery Vehi ...
(SDVT-1), based in
Pearl Harbor
Pearl Harbor is an American lagoon harbor on the island of Oahu, Hawaii, west of Honolulu. It was often visited by the Naval fleet of the United States, before it was acquired from the Hawaiian Kingdom by the U.S. with the signing of the Re ...
, and
SEAL Delivery Vehicle Team 2
Naval Special Warfare Group 3 (NSWG-3), based at the Naval Amphibious Base Coronado in California, was one of six constituent formations of the United States Naval Special Warfare Command. Until 2008, NSWG-3 was composed of two SEAL Delivery Veh ...
(SDVT-2), based in
Little Creek, Virginia
Little is a synonym for small size and may refer to:
Arts and entertainment
* ''Little'' (album), 1990 debut album of Vic Chesnutt
* ''Little'' (film), 2019 American comedy film
*The Littles, a series of children's novels by American author John P ...
. SDVT-1 operates on behalf of
Central Command and
Pacific Command in the Middle East and Indian and Pacific Oceans. SDVT-2 operates in the Atlantic and
European Command
The United States European Command (EUCOM) is one of the eleven unified combatant commands of the United States military, headquartered in Stuttgart, Germany. Its area of focus covers and 51 countries and territories, including Europe, Russia ...
and
Southern Command, and is primarily focused on supporting the activities of the
Sixth Fleet.
The SDV suffered from reliability concerns early in its lifespan.
LCDR Doug Lowe, a member of
SDV Team 1
Naval Special Warfare Group 3 (NSWG-3), based at the Naval Amphibious Base Coronado in California, was one of six constituent formations of the United States Naval Special Warfare Command. Until 2008, NSWG-3 was composed of two SEAL Delivery Vehi ...
in the 1980s, reported that his team's SDVs were operational less than 50 percent of the time.
However, reliability improved with usage: LCDR Lowe later commanded
SDV Team 2 in the 1990s and reported that his subs were ready more than 90 percent of the time.
The main failure of the SDV is its poor mobility.
The SDV can only be effectively deployed from specially modified submarines and surface ships. Although it can be transported by
C-130
The Lockheed C-130 Hercules is an American four-engine turboprop military transport aircraft designed and built by Lockheed Corporation, Lockheed (now Lockheed Martin). Capable of using unprepared runways for takeoffs and landings, the C-130 ...
airplanes, the relative scarcity of vessels capable of deploying an SDV limits its usage.
Submarines are the preferred means of deployment, as enemies can see a surface ship deploying an SDV with a crane, further limiting the SDV's mobility and usage. Modifying a surface ship to launch and recover the SDV through an underwater door, like the Italian Navy had done for its
human torpedoes in WWII, would have helped alleviate this problem.
The
Special Boat Service
The Special Boat Service (SBS) is the special forces unit of the United Kingdom's Royal Navy. The SBS can trace its origins back to the Second World War when the Army Special Boat Section was formed in 1940. After the Second World War, the Roya ...
of the
United Kingdom Special Forces
The United Kingdom Special Forces (UKSF) is a directorate comprising the Special Air Service, the Special Boat Service, the Special Reconnaissance Regiment, the Special Forces Support Group, 18 (UKSF) Signal Regiment and the Joint Special Force ...
operates three Mark 8 Mod 1 vehicles.
Operators
;
*
United States Navy
The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...
:
Navy SEALs
The United States Navy Sea, Air, and Land (SEAL) Teams, commonly known as Navy SEALs, are the U.S. Navy's primary special operations force and a component of the Naval Special Warfare Command. Among the SEALs' main functions are conducting sm ...
**
SEAL Delivery Vehicle Team 1
Naval Special Warfare Group 3 (NSWG-3), based at the Naval Amphibious Base Coronado in California, was one of six constituent formations of the United States Naval Special Warfare Command. Until 2008, NSWG-3 was composed of two SEAL Delivery Vehi ...
(SDVT-1)
**
SEAL Delivery Vehicle Team 2
Naval Special Warfare Group 3 (NSWG-3), based at the Naval Amphibious Base Coronado in California, was one of six constituent formations of the United States Naval Special Warfare Command. Until 2008, NSWG-3 was composed of two SEAL Delivery Veh ...
(SDVT-2)
;
*
Royal Navy
The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against F ...
:
Special Boat Service
The Special Boat Service (SBS) is the special forces unit of the United Kingdom's Royal Navy. The SBS can trace its origins back to the Second World War when the Army Special Boat Section was formed in 1940. After the Second World War, the Roya ...
Gallery
File:SEAL Delivery Team operations.jpg, A Navy diver and special operator from SEAL Delivery Team 2 operate an SDV from the nuclear-powered guided-missile submarine
File:SEAL Delivery Vehicle loading.jpg, An SDV being loaded aboard ''Los Angeles''-class attack submarine
File:SDVmk9 LittleBoPeep.jpg, Mark 9 SDV "Little Bo Peep" armed with a LAM-5 mine
File:US Navy 050505-N-3093M-003 A member of SEAL Delivery Vehicle Team Two (SDVT-2) prepares to launch one of the team's SEAL Delivery Vehicles (SDV) from the back of the Los Angeles-class attack submarine USS Philadelphia (SSN 690).jpg, A member of SEAL Delivery Vehicle Team Two (SDVT-2) prepares to launch a Mark 8 SDV from ''Los Angeles''-class attack submarine
See also
*
Chariot manned torpedo The Chariot was a British manned torpedo used in World War II. The Chariot was inspired by the operations of Italian naval commandos, in particular the raid on 19 December 1941 by members of the Decima Flottiglia MAS who rode "''Maiali"'' human to ...
*
Human torpedo
References
External links
Video of a SEAL Delivery Vehicle in useMilitary.com articleUSS ''Nautilus'' Museum exhibit
{{DEFAULTSORT:Seal Delivery Vehicle
Submarines of the United States Navy
United States Navy SEALs
Wet subs
Midget submarines