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Articulated pressure-resistant anthropomorphic housing for an underwater diver

Atmospheric diving suit
Atmospheric diving suit
AcronymADS
Other namesHard suit, JIM suit
UsesDeep diving
Related itemsSubmersible
The Newtsuit has fully articulated, rotary joints in the arms and legs. These provide high mobility, while remaining largely unaffected by high pressures.

An atmospheric diving suit (ADS), atmospheric pressure diving suit or single atmosphere diving suit is a small one-person articulated submersible which resembles a suit of armour, with pressure-tight joints to allow articulation while maintaining a constant internal volume and an internal pressure of one atmosphere. An ADS can enable diving at depths of up to 2,300 feet (700 m) for many hours by eliminating the majority of significant physiological dangers associated with deep diving.[1] The occupant of an ADS does not need to decompress, and there is no need for special breathing gas mixtures, so there is no danger of decompression sickness or nitrogen narcosis when the ADS is functioning properly.[2] An ADS can permit less-skilled swimmers to complete deep dives, albeit at the expense of dexterity.

Atmospheric diving suits in current use include the Newtsuit, Exosuit, Hardsuit and WASP, all of which are self-contained hard suits that incorporate propulsion units. The Hardsuit is constructed from cast aluminum (forged aluminum in a version constructed for the US Navy for submarine rescue); the upper torso hull is made from cast aluminum, while the bottom dome is machined aluminum. The WASP is of glass-reinforced plastic (GRP) body tube construction.[1]

Definition and classification

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An atmospheric diving suit is a small one-person submersible with articulated limbs encasing the diver. Water- and pressure-tight joints allow articulation while maintaining an internal pressure of one atmosphere. Mobility may be through thrusters for mid-water operation, though this is not a requirement, and articulated legs may be provided for walking on the substrate.[3]

Thornton (2000) distinguishes an ADS from a submersible in that the ADS has human powered articulated limbs, as opposed to remotely operated articulated limbs.[3] It is not clear whether this would exclude servo-assisted limbs encasing those of the operator, as a powered exoskeleton, but it might be reasonable to include them as atmospheric diving suits.

An atmospheric diving suit may be classified as a crewed submersible and a self-propelled, crewed, one-atmosphere underwater intervention device, but has also been classified as an atmospheric diving system.[3]

A characteristic of single atmosphere internal pressure is that the suit cannot passively vent gas to ambient pressure. The options are to recycle breathing gas internally, adding oxygen and removing carbon dioxide,[4] to vent surface supplied gas back to the surface through a hose which can safely withstand the external ambient pressure, or to pump it out by compressing it to ambient pressure before venting.[5]

Purpose and requirements

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The underwater environment exerts major physiological stresses on the diver, which increase with depth, and appear to impose an absolute limit to diving depth at ambient pressure. An atmospheric diving suit is a small submersible with a pressure hull which accommodates a single occupant at an internal pressure of about one atmosphere. The provision of hollow arm spaces with pressure-resistant joints to carry manually operated manipulators, and usually separate leg spaces, similarly articulated for locomotion, makes a suit resemble a bulky suit of plate armour, or an exoskeleton, with elaborate joint seals to allow articulation while maintaining internal pressure.[1]

An atmospheric diving suit is equipment intended primarily to isolate the occupant from the ambient pressure of the underwater environment, and provide any necessary life-support while the suit is in use. While using the suit, the diver will expect to perform useful work, and get to and from the place where the work is to be done. These functions require sufficient mobility, dexterity and sensory input to do the job, and this will vary depending on the details of the work. Consequently, the work possible in an atmospheric suit is limited by the suit construction.[3]

Mobility at the surface and on deck can be managed by launch and recovery systems, Mobility underwater generally requires neutral or moderately negative buoyancy, and either the ability to walk or swim, or the use of finely controllable thrusters. Both walking and thruster propulsion have been applied with some success. Swimming has not been effective.[1]

The dexterity to perform useful work is limited by joint mobility and geometry, inertia, and friction, and has been one of the more difficult engineering challenges. Haptic perception through manipulators is a major limitation on finer control, as the friction of the joints and seals greatly reduces the sensitivity available.[3]

Operator visual input is relatively easy to provide directly by using transparent viewports. A wide field of view can be achieved simply and structurally effectively by using a transparent partial dome over the diver's head. Close-up views of the manipulators are limited by joint flexibility and geometry of the suit's arms. External sound and temperature perception are greatly attenuated, and there is no sense of touch through the suit. Communications must be provided by technology, as there is normally no-one else in the immediate vicinity.[3]

Design constraints

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The main environmental factors affecting design are the ambient hydrostatic pressure of the maximum operating depth, and ergonomic considerations regarding the potential range of operators.[3] The structure and mechanics of the suit must reliably withstand the external pressure, without collapsing or deforming sufficiently to cause seals to leak or joints to experience excessive friction, and the full range of movement must not change the internal or external displaced volume, as this would have consequences for the amount of force required to move the joints in addition to the friction of the joint seals. Insulation is relatively simple, and can be applied to the inside of the suit and in the form of clothing on the diver. Active heating and cooling are also possible using well established technology. Mass changes can be used to provide initial and emergency buoyancy conditions by way of fixed and ditchable ballast weights.[3]

Ergonomic considerations include the size and strength of the user. The interior dimensions must fit or be modifiable to fit a reasonable range of operators, and operating forces on joints must be reasonably practicable. The field of vision is constrained by the helmet design or viewport positioning, though closed circuit video can extend it considerably in any direction. General underwater conditions of visibility and water movement must be manageable for the range of conditions in which the suit is expected to be used. Marine thrusters may be mounted on the suit to help with maneuvering and positioning,[3] and sonar and other scanning technologies may help provide an augmented external view.[3]

Factors affecting the design and construction:

  • Pressure hull form – Sufficient volume for necessary internal systems, constrained by size and shape of human operator, and by shapes with high resistance to collapse under external pressure.
    • Displacement – Need for neutral buoyancy at work and positive buoyancy in emergencies
    • Hydrodynamics – cruise speed
    • Propulsion – Thruster type and arrangement
    • Ergonomics – Anthropometry, joint design for limb articulation under external pressure.
  • Working depth rating – Strength, rigidity and density of materials. Buckling, constant volume, and joint friction limiting factors
    • Construction materials
    • Safety .

Systems

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Systems usually include:

On-board life-support:[4]

  • Breathing gas supply, monitoring and recycling[4]
    • Monitoring of oxygen partial pressure, carbon dioxide level[4]
    • Carbon dioxide scrubbing[4]
    • Oxygen replenishment, oxygen storage cylinders[4]
    • Emergency rebreather circulation systems.[4]
  • Thermal management

Buoyancy and trim ballast systems:

  • Control of basic buoyancy
  • Adjustment of trim – control of the positions of centre of gravity and centre of buoyancy.
  • Compensating trim and buoyancy for payload effects.
  • Achieving stability when submerged and in emergency Compensation for variations in water density due to stratification (temperature and salinity variations).
  • Compensation for pressure effects.
  • Adjustable and ditchable ballast systems.

Movement, propulsion, and navigation systems:

  • Propulsion systems, thrusters.
  • Control of vertical, lateral and forward movement, and rotation and orientation in three dimensions.

Safety and emergencies

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Classes of emergency:[citation needed]

  • Fires and fire extinguishing methods.
  • Leaks and flooding.
  • Entanglement.
  • Life-support system failures,[4] toxic hazards.
  • Loss of communications and emergency communications options
  • Loss of power and sensors.

There are also physiological and psychological effects of prolonged isolation underwater due to sensory deprivation and thermal stress.

Operating skills and procedures

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Operator skills:

  • Standard operating procedures:
    • Buoyancy set up of the suit (ballasting will vary depending on the mass and centre of gravity of the operator)
    • Flying in and around underwater structure
    • Reporting life support system readings while hovering
    • Through-water communications protocols
    • Rigging preparation and rigging work
      • Connecting the umbilical to a down-line
      • Attaching a shackle to work on the bottom and in mid-water
      • Use of buoyant lifting bags
    • Carrying loads and managing a tool basket
    • Use of powered underwater tools
    • Underwater measurement
  • Emergency procedures:
    • Climbing the umbilical in the event of power loss, entrapment)
    • Emergency jettison systems

Work skills

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These may include submarine rescue, salvage, inspection and non-destructive testing, and typical oilfield construction and maintenance tasks, or a range of scientific observation and sampling activities.

Operator requirements

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  • The operator must fit inside the suit, be able to move their limbs effectively, and be able to get out again.
  • The operator must be able to reach and to operate electronics panels and life support systems, be able to jettison ballast, operate umbilical and thruster cable cutters.
  • The operator must be physically, medically and psychologically fit for the work.

Hazards and failure modes

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The primary structural failure modes of an ADS are buckling collapse in compression, leaks, and lockup of joints. Leaks and buckling in compression both cause a reduction in buoyancy. Joint leaks and locking of articulating joints may be reversible when pressure is reduced. Electrically ignited fire is also possible.

Systems failures may include loss of power, communications, or propulsion, or life-support systems failure, such as failure of scrubbing the carbon dioxide from the breathing air, or failure of internal temperature control. Recovery from most of these would be by aborting the dive and making an emergency ascent. Bailout to emergency breathing system and ditching of ballast to establish positive buoyancy may be necessary. If the ADS is tethered it can be lifted. The most dangerous consequence is catastrophic leakage, which is likely to be fatal.

There has been one fatal incident involving an ADS. A WASP was dropped 80 feet (25 m) in August 1999 due to a structural failure in a recently tested launch and recovery system, and the diver was killed by the impact with the launch platform. This is in the context of tens of thousands of operational man-hours by WASPs without serious incidents.[1]

Comparison with alternative technologies

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Several advantages over ambient pressure diving are claimed, but dexterity is less. There are also advantages and disadvantages in comparison with remotely operated underwater vehicles (ROVs):

  • No decompression is required. Decompression from saturation takes approximately 1 day per 30 msw plus 1 day, during which time the divers are unproductive. This is particularly expensive when the total dive time is relatively short.[1]
  • Consecutive dives can be made to any depths within the operating range. Saturation divers are very limited in safe excursion range from storage depth.[1] An ADS depth excursions are limited only by maximum working depth.
  • Lateral range is comparable with ROVs.
  • Thrusters, when provided, can provide moderate mid-water and current capability.[1]
  • Manipulatory capacity and dexterity are better than ROVs. Less special tooling is required for most work. Depth perception of the diver is better than remote viewing via a ROV cameras.[1]
  • Deep applications are possible compared with ambient pressure diving. The industry-accepted maximum depth for routine saturation diving is 300 msw. ADS operations can go deeper. However, ROVs and crewed submersibles can go much deeper. Maximum depth capability for ROV and crewed submersibles is .

Current suits

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Exosuit
Side view of Exosuit
Back view of Exosuit

In 1987, the "Newtsuit" was developed by the Canadian engineer Phil Nuytten, and a version was put into production as the "Hardsuit" by Hardsuits International.[9] The Newtsuit is constructed to function like a 'submarine you can wear', allowing the diver to work at normal atmospheric pressure even at depths of over 1,000 feet (300 m). Made of wrought aluminium, it had fully articulated joints so the diver can move more easily underwater. The life support system provides 6–8 hours of air, with an emergency back-up supply of an additional 48 hours. The Hardsuit was used to salvage the bell from the wreck of the SS Edmund Fitzgerald in 1995. The latest version of the Hardsuit designed by Oceanworks, the "Quantum 2", uses higher power commercially available ROV thrusters for better reliability and more power as well as an atmospheric monitoring system to monitor the environmental conditions in the cabin. A more recent design by Nuytten is the Exosuit, a relatively lightweight and low powered suit intended for marine research.[25] It was first used in 2014 at the Bluewater and Antikythera underwater research expeditions.[26][27]

US Navy ADS 2000 on launch and recovery platform after a certification dive in August 2006

The ADS 2000 was developed jointly with OceanWorks International and the US Navy in 1997,[28] as an evolution of the Hardsuit to meet US Navy requirements. The ADS 2000 provides increased depth capability for the US Navy's Submarine Rescue Program. Manufactured from forged T6061 aluminum alloy, it uses an advanced articulating joint design based on the Hardsuit joints. Capable of operating in up to 2,000 feet (610 m) of seawater for a normal mission of up to six hours, it has a self-contained, automatic life support system.[29] Additionally, the integrated dual thruster system allows the pilot to navigate easily underwater. It became fully operational and certified by the US Navy off southern California on 1 August 2006, when Chief Navy Diver Daniel Jackson submerged to 2,000 feet (610 m).[30]

From the project's beginning until 2011, the US navy spent $113 million on the ADS 2000.[31]

Atmospheric Diving System (ADS 2000)
A diver wearing the Oceanworks ADS 2000 suit with the helmet dome open stands in an indoor test pool and talks to two other naval officers
Atmospheric Diving System at the Naval Reserve Deep Submergence Unit Detachment at Naval Air Station North Island
The ADS 2000 suit is lowered into the sea from the side of a ship
Atmospheric Diving System lowered into the water from the salvage ship USNS Grasp (T-ARS-51)

See also

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References

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  1. 1 2 3 4 5 6 7 8 9 10 11 Thornton, Mike; Randall, Robert E.; Albaugh, E. Kurt (1 January 2001). "Subsea Technology: Atmospheric diving suits bridge gap between saturation diving and ROV units". Retrieved 20 September 2023.
  2. 1 2 3 "WASP Specifications" (PDF). Archived from the original (PDF) on 3 March 2014. Retrieved 27 February 2014.
  3. 1 2 3 4 5 6 7 8 9 10 Thornton, Michael Albert (December 2000). A Survey and Engineering Design of Atmospheric Diving Suits (PDF) (Report). Texas A&M University.
  4. 1 2 3 4 5 6 7 8 "The Exosuit Diving Suit Stays Flexible Underwater". Machne Design. 18 February 2009. Retrieved 16 August 2025.
  5. ↑ This is basic physics
  6. ↑ "Triton 36000/2: Full Ocean Depth". fivedeeps.com. Retrieved 2023-01-16.
  7. 1 2 Ratcliffe, John E. (Spring 2011). "Bells, Barrels and Bullion: Diving and Salvage in the Atlantic World, 1500 to 1800". Nautical Research Journal. 56 (1): 35–56.
  8. ↑ "The Carmagnolle Brothers Armoured Dress". Historical Diving Times (37). Autumn 2005.
  9. ↑ "Historique" (in French). Association Les Pieds Lourds. Retrieved 6 April 2015.
  10. ↑ Pickford, Nigel (1998). Lost Treasure Ships of the 20th Century. Washington, DC: National Geographic Society. p. 152. ISBN 0792274725.
  11. ↑ Marx, Robert F (1990). The History of Underwater Exploration. Courier Dover Publications. pp. 79–80. ISBN 0-486-26487-4.
  12. ↑ Burke, Edmund H (1966). The Diver's World: An Introduction. Van Nostrand. p. 112.
  13. 1 2 3 Loftas, Tony (7 June 1973). "JIM: homo aquatico-metallicum". New Scientist. 58 (849): 621–623. ISSN 0262-4079. Enthusiasm for these pressure-resisted suits waned with the evolution of free-diving during and immediately after the Second World War. ... [T]he major innovative impetus was reserved almost exclusively for scuba gear
  14. ↑ Acott, Chris (1999). "A brief history of diving and decompression illness". South Pacific Underwater Medicine Society Journal. 29 (2). ISSN 0813-1988. OCLC 16986801. Archived from the original on 5 September 2011. Retrieved 6 April 2015.
  15. ↑ Taylor, Colin (October 1997). "Jim, but not as we know it". Diver. Archived from the original on 2014-12-26.. The article was reprinted, without the author's name and slightly abbreviated as: "The Joseph Peress Diving Suit". The Scribe, Journal of Babylonian Jewry (71): 24. April 1999.
  16. ↑ "Jim, but not as we know it". Divernet. Retrieved 6 April 2015.. This article seems to be mostly based on the article in The Scribe (1999)
  17. ↑ Carter, RC Jr. (1976). "Evaluation of JIM: A One-Atmosphere Diving Suit". US Navy Experimental Diving Unit Technical Report. NEDU-05-76. Archived from the original on December 9, 2008. Retrieved 2008-07-22.
  18. ↑ Kesling, Douglas E (2011). Pollock, NW (ed.). "Atmospheric Diving Suits – New Technology May Provide ADS Systems that are Practical and Cost-Effective Tools for Conducting Safe Scientific Diving, Exploration, and Undersea Research". Diving for Science 2011. Proceedings of the American Academy of Underwater Sciences 30th Symposium. Dauphin Island, AL. Retrieved 6 April 2015.{{cite journal}}: CS1 maint: deprecated archival service (link)
  19. ↑ Carter, RC Jr. (1976). "Evaluation of JIM: A One-Atmosphere Diving Suit". US Navy Experimental Diving Unit Technical Report. NEDU-05-76. Archived from the original on 9 December 2008. Retrieved 6 April 2015.
  20. 1 2 Curley, MD; Bachrach, AJ (September 1982). "Operator performance in the one-atmosphere diving system JIM in water at 20 degrees C and 30 degrees C". Undersea Biomedical Research. 9 (3): 203–12. PMID 7135632. Retrieved 6 April 2015.{{cite journal}}: CS1 maint: deprecated archival service (link)
  21. ↑ Nuytten, P (1998). "Life support in small one-atmosphere underwater work systems". Life Support & Biosphere Science. 5 (3): 313–7. PMID 11876198.
  22. ↑ "The Exosuit: What Tony Stark Would Wear Underwater". Gizmodo. 28 February 2014. Retrieved 6 April 2015.
  23. ↑ Hilts, Philip J. (2015-01-01). "Robotic Men and Robotic Vehicles Explore Ancient Shipwrecks". Scientific American. Retrieved 2025-08-03.
  24. ↑ "New technology: The Exosuit". Return to Antikythera. Woods Hole Oceanographic Institution. 2014. Retrieved 21 September 2016.
  25. ↑ "Military ADS". OceanWorks International. 2015. Retrieved 6 April 2015.
  26. ↑ Logico, Mark (3 August 2006). "Navy Chief Submerges 2,000 Feet, Sets Record". U.S. Navy. Archived from the original on 22 May 2011. Retrieved 13 May 2011.
  27. ↑ Logico, Mark G. (7 August 2006). "Navy Diver Sets Record with 2,000 foot Dive". Navy News. Archived from the original on 30 August 2006.
  28. ↑ Department of the Navy Fiscal Year 2017 Budget Estimates (PDF) (Report). US Department of the Navy. 31 Jan 2011. p. 164.
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  • Harris, Gary L (1995). Ironsuit: The History of the Atmospheric Diving Suit. Best Pub. Co. ISBN 0-941332-25-X.
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