Atmospheric diving suit
Template:Short description Template:Use British English Template:Infobox diving equipment
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 Template:Convert for many hours by eliminating the majority of significant physiological dangers associated with deep diving.<ref name="Offshore" /> 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.<ref name="Wasp specifications" /> 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 the 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.<ref name="Offshore" />
Definition and classification
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.<ref name="Thornton 2000" />
Thornton (2000) distinguishes an ADS from a submersible in that the ADS has human powered articulated limbs, as opposed to remotely operated articulated limbs.<ref name="Thornton 2000" /> 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.<ref name="Thornton 2000" />
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,<ref name="Machine Design" /> 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.<ref>This is basic physics</ref>
Purpose and requirements
Template:See also 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.<ref name="Offshore" />
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.<ref name="Thornton 2000" />
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.<ref name="Offshore" />
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.<ref name="Thornton 2000" />
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.<ref name="Thornton 2000" />
Design constraints
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.<ref name="ADAS ADS" /><ref name="Thornton 2000" /> 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.<ref name="Thornton 2000" />
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,<ref name="ADAS ADS" /><ref name="Thornton 2000" /> and sonar and other scanning technologies may help provide an augmented external view.<ref name="Thornton 2000" />
Factors affecting the design and construction:<ref name="ADAS ADS" />
- 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.<ref name="ADAS ADS" />
- Displacement – Need for neutral buoyancy at work and positive buoyancy in emergencies<ref name="ADAS ADS" />
- Hydrodynamics – cruise speed<ref name="ADAS ADS" />
- Propulsion – Thruster type and arrangement<ref name="ADAS ADS" />
- 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<ref name="ADAS ADS" />
- Construction materials<ref name="ADAS ADS" />
- Safety<ref name="ADAS ADS" /> .
Systems
Systems usually include:
On-board life-support:<ref name="ADAS ADS" /><ref name="Machine Design" />
- Breathing gas supply, monitoring and recycling<ref name="ADAS ADS" /><ref name="Machine Design" />
- Monitoring of oxygen partial pressure, carbon dioxide level<ref name="ADAS ADS" /><ref name="Machine Design" />
- Carbon dioxide scrubbing<ref name="ADAS ADS" /><ref name="Machine Design" />
- Oxygen replenishment, oxygen storage cylinders<ref name="ADAS ADS" /><ref name="Machine Design" />
- Emergency rebreather circulation systems.<ref name="Machine Design" />
- Thermal management<ref name="ADAS ADS" />
Buoyancy and trim ballast systems:<ref name="ADAS ADS" />
- Control of basic buoyancy<ref name="ADAS ADS" />
- Adjustment of trim – control of the positions of centre of gravity and centre of buoyancy.<ref name="ADAS ADS" />
- Compensating trim and buoyancy for payload effects.<ref name="ADAS ADS" />
- Achieving stability when submerged and in emergency<ref name="ADAS ADS" /> Compensation for variations in water density due to stratification (temperature and salinity variations).<ref name="ADAS ADS" />
- Compensation for pressure effects.<ref name="ADAS ADS" />
- Adjustable and ditchable ballast systems.<ref name="ADAS ADS" />
Movement, propulsion, and navigation systems:<ref name="ADAS ADS" />
- Propulsion systems, thrusters.<ref name="ADAS ADS" />
- Control of vertical, lateral and forward movement, and rotation and orientation in three dimensions.<ref name="ADAS ADS" />
Safety and emergencies
Classes of emergency:Template:Cn
- Fires and fire extinguishing methods.
- Leaks and flooding.
- Entanglement.
- Life-support system failures,<ref name="Machine Design" /> 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
Operator skills:<ref name="ADAS ADS" />
- Standard operating procedures:<ref name="ADAS ADS" />
- Buoyancy set up of the suit (ballasting will vary depending on the mass and centre of gravity of the operator)<ref name="ADAS ADS" />
- Flying in and around underwater structure<ref name="ADAS ADS" />
- Reporting life support system readings while hovering<ref name="ADAS ADS" />
- Through-water communications protocols<ref name="ADAS ADS" />
- Rigging preparation and rigging work<ref name="ADAS ADS" />
- Connecting the umbilical to a down-line<ref name="ADAS ADS" />
- Attaching a shackle to work on the bottom and in mid-water<ref name="ADAS ADS" />
- Use of buoyant lifting bags<ref name="ADAS ADS" />
- Carrying loads and managing a tool basket<ref name="ADAS ADS" />
- Use of powered underwater tools<ref name="ADAS ADS" />
- Underwater measurement<ref name="ADAS ADS" />
- Emergency procedures:<ref name="ADAS ADS" />
- Climbing the umbilical in the event of power loss, entrapment)<ref name="ADAS ADS" />
- Emergency jettison systems<ref name="ADAS ADS" />
Work skills
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.<ref name="ADAS ADS" />
Operator requirements
- The operator must fit inside the suit, be able to move their limbs effectively, and be able to get out again.<ref name="ADAS ADS" />
- 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.<ref name="ADAS ADS" />
- The operator must be physically, medically and psychologically fit for the work.<ref name="ADAS ADS" />
Hazards and failure modes
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 Template:Convert 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.<ref name="Offshore" />
Comparison with alternative technologies
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.<ref name="Offshore" />
- Consecutive dives can be made to any depths within the operating range. Saturation divers are very limited in safe excursion range from storage depth.<ref name="Offshore" /> An ADS depth excursions are limited only by maximum working depth.<ref name="ADAS ADS" />
- Lateral range is comparable with ROVs.<ref name="ADAS ADS" />
- Thrusters, when provided, can provide moderate mid-water and current capability.<ref name="Offshore" />
- 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.<ref name="Offshore" />
- 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.<ref name="Offshore" /> However, ROVs and crewed submersibles can go much deeper. Maximum depth capability for ROV and crewed submersibles is full ocean depth.<ref name="Technology specifications" />
For some work the most effective method can be a combination of ADS and ROV; in other cases, ADS and ambient pressure diver.<ref name="Offshore" />
History
Early designs
Template:Multiple image In 1715, British inventor John Lethbridge constructed a "diving engine". Essentially a wooden barrel about Template:Convert in length with two holes for the diver's arms sealed with leather cuffs, and a Template:Convert viewport of thick glass. It was reportedly used to dive as deep as Template:Convert, and was used to salvage substantial quantities of silver from the wreck of the East Indiaman Template:Ship, which sank in 1719 off the Cape Verde islands.<ref name="tanads" /> A similar design made of copper was used by Jacob Rowe on the same salvage contract.<ref name="Ratcliffe 2011" />
The first armored suit with real joints, designed as leather pieces with rings in the shape of a spring (also known as accordion joints), was designed by Englishman W. H. Taylor in 1838. The diver's hands and feet were covered with leather. Taylor also devised a ballast tank attached to the suit that could be filled with water to attain negative buoyancy. While it was patented, the suit was never actually produced. It is considered that its weight and bulk would have rendered it nearly immobile underwater.<ref name="tanads" />
Lodner D. Phillips designed the first completely enclosed ADS in 1856. His design comprised a barrel-shaped upper torso with domed ends with ball and socket joints in the articulated arms and legs. The arms had joints at shoulder and elbow, and the legs at knee and hip. The suit included a ballast tank, a viewing port, entrance through a manhole cover on top, a hand-cranked propeller, and rudimentary manipulators at the ends of the arms. Breathing air was to be supplied from the surface via hose. There is no indication that Phillips' suit was ever constructed.<ref name="tanads" />
The first properly anthropomorphic design of ADS, built by the Carmagnolle brothers of Marseille, France in 1882, featured rolling convolute joints consisting of closely fitting concentric spherical sections sealed by watertight cloth membranes. The suit had 22 of these joints: four in each leg, six in each arm, and two in the torso. The helmet had 25 individual Template:Convert glass viewports spaced at the average separation of the human eyes.<ref name="Historic diving times 2005" /> Weighing Template:Convert, the Carmagnole ADS never worked properly and its joints never were entirely waterproof. It is now on display at the French National Navy Museum in Paris.<ref name="pieds-lourds" />
Another design was patented in 1894 by inventors John Buchanan and Alexander Gordon from Melbourne, Australia. The construction was based on a frame of spiral wires covered with waterproof material. The design was improved by Alexander Gordon by attaching the suit to the helmet and other parts and incorporating jointed radius rods in the limbs. This resulted in a flexible suit which could withstand high pressure. The suit was manufactured by British firm Siebe Gorman and trialed in Scotland in 1898.Template:Cn Template:Multiple image
American designer Macduffee constructed the first suit to use ball bearings to provide joint movement in 1914; it was tested in New York to a depth of Template:Convert, but was not very successful. A year later, Harry L. Bowdoin of Bayonne, New Jersey, made an improved ADS with oil-filled rotary joints. Each joint has a small duct to its interior to allow equalization of pressure. The suit was designed to have eighteen joints: four in each arm and leg, and one in each thumb. Four viewing ports and a chest-mounted lamp were intended to assist underwater vision. There is no evidence that Bowdoin's suit was ever built, or that it would have worked if it had been.<ref name="tanads" />
Atmospheric diving suits built by Neufeldt and Kuhnke of Germany were used during the salvage of gold and silver bullion from the wreck of the British ship SS Egypt, an 8,000 ton P&O liner that sank in May 1922. The suit was relegated to duties as an observation chamber at the wreck's depth of Template:Convert,<ref name="Pickford" /> and was successfully used to direct mechanical grabs which opened up the bullion storage. In 1917, Benjamin F. Leavitt of Traverse City, Michigan, dived on the SS Pewabic which sank to a depth of Template:Convert in Lake Huron in 1865, salvaging 350 tons of copper ore. In 1923, he went on to salvage the wreck of the British schooner Cape Horn which lay in Template:Convert of water off Pichidangui, Chile, salvaging $600,000 worth of copper. Leavitt's suit was of his own design and construction. The most innovative aspect of Leavitt's suit was the fact that it was completely self-contained and needed no umbilical, the breathing mixture being supplied from a tank mounted on the back of the suit. The breathing apparatus incorporated a scrubber and an oxygen regulator and could last for up to a full hour.<ref name="Marx 1990" />
In 1924 the Reichsmarine tested the second generation of the Neufeldt and Kuhnke suit to Template:Convert, but limb movement was very difficult and the joints were judged not to be fail-safe, in that if they were to fail, there was a possibility that the suit's integrity would be violated. However, these suits were used by the Germans as armored divers during World War II and were later taken by the Western Allies after the war.
From 1929 to 1931 two atmospheric pressure one-person submersible "suits" designed by Carl Wiley were used in the successful salvage of the steamship Islander which sank in the Stevens Passage near Juneau, Alaska on 15 August 1901, with a large amount of gold dust in the cargo. The suits operated at a maximum depth of Template:Convert. They were each equipped with a mechanical arm with a grasping claw at the end operated from inside the suit. The suits were capable of traversing a hard, reasonably smooth substrate on wheels, and were used to place the steel cables used to raise the wreck by tidal lift (with an Template:Convert tide range) under a catamaran barge in stages, while it was towed to shallow water. The suits had electrical power, and the diver/pilot used an oxygen rebreather. These suits have also been described as diving bells and observation chambers, as they do not match the usual definition of an atmospheric diving suit, but they were more than just observation chambers, being capable of work, and were independently mobile, so do not match the usual definition of a diving bell either. They were an unusual type of tethered crewed submersible.<ref name="Popular Mechanics Oct 1931" />
In 1952, Alfred A. Mikalow constructed an ADS using ball and socket joints, specifically for the purpose of locating and salvaging sunken treasure. The suit was reported to be capable of diving to Template:Convert depth and was successfully used to dive on the wreck of SS City of Rio de Janeiro near Fort Point, San Francisco at a depth of Template:Convert. Mikalow's suit had various interchangeable instruments which could be mounted on the end of the arms in place of the original manipulators. It carried seven 90-cubic foot high pressure cylinders to provide breathing gas and control buoyancy. The ballast compartment covered the gas cylinders. For communication, the suit used hydrophones.<ref name="Burke 1966" />
The modern suit
Peress' Tritonia
Although various atmospheric suits had been developed during the Victorian era, none of these suits overcame the basic design problem of constructing a joint which would remain flexible and watertight at depth without seizing up under pressure.
Pioneering British diving engineer, Joseph Salim Peress, invented the first truly usable atmospheric diving suit, the Tritonia, in 1932 and was later involved in the construction of the famous JIM suit. Having a natural talent for engineering design, he challenged himself to construct an ADS that would keep divers dry and at atmospheric pressure, even at great depth. In 1918, Peress began working for WG Tarrant at Byfleet, United Kingdom, where he was given the space and tools to develop his ideas about constructing an ADS. His first attempt was an immensely complex prototype machined from solid stainless steel.
In 1923, Peress was asked to design a suit for salvage work on the wreck of SS Egypt which had sunk in the English Channel. He declined, on the grounds that his prototype suit was too heavy for a diver to handle easily, but was encouraged by the request to begin work on a new suit using lighter materials. By 1929 he believed he had solved the weight problem, by using cast magnesium instead of steel, and had also managed to improve the design of the suit's joints by using a trapped cushion of oil to keep the surfaces moving smoothly. The oil was virtually non-compressible and readily displaceable, which would allow the limb joints to move freely even under great pressure. Peress claimed the Tritonia suit could function at Template:Convert, where the pressure was Template:Convert, although this was never proven.<ref name="loftas1973" />
In 1930, Peress revealed the Tritonia suit.<ref name="dive_hx" /> By May it had completed trials and was publicly demonstrated in a tank at Byfleet. In September Peress' assistant Jim Jarret dived in the suit to a depth of Template:Convert in Loch Ness. The suit performed perfectly, the joints proving resistant to pressure and moving freely even at depth. The suit was offered to the Royal Navy which turned it down, stating that Navy divers never needed to descend below Template:Convert. In October 1935 Jarret made a successful deep dive to more than Template:Convert on the wreck of the Template:RMS off south Ireland, followed by a shallower dive to Template:Convert in the English Channel in 1937 after which, due to lack of interest, the Tritonia suit was retired.Template:Cn
The development in atmospheric pressure suits stagnated in the 1940s through 1960s, as efforts were concentrated on solving the problems of deep diving by dealing with the physiological problems of ambient pressure diving instead of avoiding them by isolating the diver from the pressure. Although the advances in ambient pressure diving (in particular, with scuba gear) were significant, the limitations brought renewed interest to the development of the ADS in the late 1960s.<ref name="loftas1973" />
The JIM suit
{{#invoke:Labelled list hatnote|labelledList|Main article|Main articles|Main page|Main pages}} The Tritonia suit spent about 30 years in an engineering company's warehouse in Glasgow, where it was discovered, with Peress' help, by two partners in the British firm Underwater Marine Equipment, Mike Humphrey and Mike Borrow, in the mid-1960s.<ref name="loftas1973" /><ref name="scribe71" /><ref name="divernet" /> UMEL would later classify Peress' suit as the "A.D.S Type I", a designation system that would be continued by the company for later models. In 1969, Peress was asked to become a consultant to the new company created to develop the JIM suit, named in honour of the diver Jim Jarret.<ref name="Carter 1976" />
The first JIM suit was completed in November 1971 and underwent sea trials from Template:HMS in early 1972. In 1976, it set a record of five hours and 59 minutes for the longest working dive below Template:Convert, at a depth of Template:Convert. The first JIM suits were constructed from cast magnesium for its high strength-to-weight ratio and weighed approximately Template:Convert in air, including the occupant. They were Template:Convert in height and had a maximum operating depth of Template:Convert. The suit had a positive buoyancy of Template:Convert. Ballast was attached to the suit's front and could be jettisoned from inside, allowing the suit to ascend to the surface at approximately Template:Convert.<ref name="Kesling 2011" /> The suit also incorporated a communication link and an umbilical connection that could be released by the diver. The original JIM suit had eight annular oil-supported universal joints, one at each hip, knee, shoulder and lower arm. The JIM operator received air through an oral/nasal mask that attached to a lung-powered scrubber that had a life support duration of approximately 72 hours.<ref name="nedu76" /> Operations in arctic conditions with water temperatures of Template:Cvt for over 5 hours were successfully carried out using woolen thermal protection and neoprene boots. In Template:Cvt water the suit was reported to be uncomfortably hot during heavy work.<ref name="Curley and Bachrach 1982" />
As technology improved and operational knowledge grew, Oceaneering upgraded their fleet of JIMs. The magnesium construction was replaced with glass-reinforced plastic (GRP) and the single joints with segmented ones, each allowing seven degrees of motion, and when added together giving the operator a very great range of motion. In addition, the four-port domed top of the suit was replaced by a transparent acrylic dome as used on WASP, which provided a much better field of vision. Trials were also carried out by the Ministry of Defence on a flying Jim suit powered from the surface through an umbilical cable. This resulted in a hybrid suit with the ability of working on the sea bed as well as mid water.<ref name="Curley and Bachrach 1982" />
In addition to upgrades to the JIM design, other variations of the original suit were constructed. The first, named the SAM Suit (designated A.D.S III), was a completely aluminium model. A smaller and lighter suit, it was more anthropomorphic than the original JIMs and was depth-rated to Template:Convert. Attempts were made to limit corrosion by the use of a chromic anodizing coating applied to the arm and leg joints, which gave them an unusual green color. The SAM suit stood at Template:Convert in height, and had a life support duration of 20 hours. Only three SAM suits would be produced by UMEL before the design was shelved. The second, named the JAM suit (designated A.D.S IV), was constructed of glass-reinforced plastic (GRP) and was depth-rated for around Template:Convert.<ref name="Nuytten 1998" />
WASP
The WASP atmospheric diving system is partway between a one-person submersible and an atmospheric diving suit, in that there are articulated arms which contain and are moved by the operator's arms, but the operator's legs are contained in a rigid housing. Mobility is provided by two vertical and two horizontal foot-switch controlled electrical marine thrusters. Operating depth was quoted as Template:Convert<ref name="Wasp specifications" />
WASP is Template:Convert high, Template:Convert wide, and Template:Convert front to back. Ballasted weight in air approximately Template:Convert, for neutral buoyancy in water, but buoyancy can be increased by up to Template:Convert during operation, and ballast can be jettisoned in an emergency. WASP is transported on a support frame.<ref name="Wasp specifications" />
Current suits
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.<ref name="Ratcliffe 2011" /> 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 Template:Convert. 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.<ref name="Gizmodo" /> It was first used in 2014 at the Bluewater and Antikythera underwater research expeditions.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name="Exosuit" />
The ADS 2000 was developed jointly with OceanWorks International and the US Navy in 1997,<ref name="oceanworks" /> 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 Template:Convert of seawater for a normal mission of up to six hours, it has a self-contained, automatic life support system.<ref name="Logico 2006b" /> 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 Template:Convert.<ref name="Logico 2006" />
From the project's beginning until 2011, the US navy spent $113 million on the ADS 2000.<ref name="Budget 2011" />
See also
References
<references> <ref name="ADAS ADS" >{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
<ref name="Budget 2011">Template:Cite report</ref>
<ref name="Burke 1966">Template:Cite book</ref>
<ref name="Carter 1976">Template:Cite journal</ref>
<ref name="Curley and Bachrach 1982">Template:Cite journal</ref>
<ref name="dive_hx">Template:Cite journal</ref>
<ref name="divernet">{{#invoke:citation/CS1|citation |CitationClass=web }}. This article seems to be mostly based on the article in The Scribe (1999)</ref>
<ref name="Exosuit">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
<ref name="Gizmodo">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
<ref name="Historic diving times 2005">Template:Cite journal</ref>
<ref name="Kesling 2011">Template:Cite journal</ref>
<ref name="Logico 2006b" >{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
<ref name="Logico 2006" >{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
<ref name="loftas1973" >Template:Cite journal</ref>
<ref name="Machine Design" >{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
<ref name="Marx 1990">Template:Cite book</ref>
<ref name="nedu76" >Template:Cite journal</ref>
<ref name="Nuytten 1998" >Template:Cite journal</ref>
<ref name="oceanworks">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
<ref name="Offshore" >{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
<ref name="Pickford" >Template:Cite book</ref>
<ref name="pieds-lourds">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
<ref name="Popular Mechanics Oct 1931" >Template:Cite magazine</ref>
<ref name="Ratcliffe 2011" >Template:Cite journal</ref>
<ref name="scribe71" >Template:Cite journal. The article was reprinted, without the author's name and slightly abbreviated as: Template:Cite journal</ref>
<ref name="tanads" >{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
<ref name="Technology specifications" >{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
<ref name="Thornton 2000" >Template:Cite report</ref>
<ref name="Wasp specifications" >{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> </references>