Atmospheric diving suit

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. 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, and sonar and other scanning technologies may help provide an augmented external view.[3]

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 in the modern era. A WASP was dropped 25m 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]

Jacob Rowe's copper diving dress, built in the 1710s

Modern replica on display at the History of Diving Museum, Florida (inaccurate, Lethbidge's suit was not curved)

In 1715, British inventor John Lethbridge constructed a "diving engine". Essentially a wooden barrel about 6 feet (1.8 m) in length with two holes for the diver's arms sealed with leather cuffs, and a 4-inch (100 mm) viewport of thick glass. It was reportedly used to dive as deep as 60 feet (18 m), and was used to salvage substantial quantities of silver from the wreck of the East Indiaman Vansittart, which sank in 1719 off the Cape Verde islands.[4] A similar design made of copper was used by Jacob Rowe on the same salvage contract.[5]

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.[4]

Lodner D. Phillips designed the first completely enclosed ADS in 1856. His design comprised a barrel-shaped upper torso with domed ends and included 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. Air was to be supplied from the surface via hose. There is no indication, however, Phillips' suit was ever constructed.[4]

Suit built by Carmagnolle brothers in 1882, was the first anthropomorphic design.

The first properly anthropomorphic design of ADS, built by the Carmagnolle brothers of Marseilles, France in 1882, featured rolling convolute joints consisting of partial sections of concentric spheres formed to create a close fit and kept watertight with a waterproof cloth. The suit had 22 of these joints: four in each leg, six per arm, and two in the body of the suit. The helmet had 25 individual 2-inch (50 mm) glass viewing ports spaced at the average distance of the human eyes.[6] Weighing 830 pounds (380 kg), 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.[7]

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.

US Navy 1913 ADS

1913 US Navy ADS at Man in the Sea Museum, Panama City, FL with the lobster claws

Close up view of two-jawed grasper and pitch-yaw wrist joint on 1913 US Navy armored diving suit

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 214 feet (65 m), but was not very successful. A year later, Harry L. Bowdoin of Bayonne, New Jersey, made an improved ADS with oil-filled rotary joints. The joints use a small duct to the interior of the joint to allow equalization of pressure. The suit was designed to have four joints in each arm and leg, and one joint in each thumb, for a total of eighteen. Four viewing ports and a chest-mounted lamp were intended to assist underwater vision. Unfortunately there is no evidence that Bowdoin's suit was ever built, or that it would have worked if it had been.[4]

Atmospheric diving suits built by German firm Neufeldt and Kuhnke 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 170 metres (560 ft),[8] 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 182 feet (55 m) 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 220 feet (67 m) 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.[9]

In 1924 the Reichsmarine tested the second generation of the Neufeldt and Kuhnke suit to 530 feet (160 m), 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-man 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 365 ft. They were each equipped with a mechanical arm with a grasping claw at the end operated from within 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 (18 ft 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 manned submersible.[10]

In 1952, Alfred A. Mikalow constructed an ADS employing ball and socket joints, specifically for the purpose of locating and salvaging sunken treasure. The suit was reportedly capable of diving to depths of 1,000 feet (300 m) and was used successfully to dive on the sunken vessel SS City of Rio de Janeiro in 328 feet (100 m) of water near Fort Point, San Francisco. Mikalow's suit had various interchangeable instruments which could be mounted on the end of the arms in place of the usual 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.[11]

Two divers, one wearing the "Tritonia" ADS and the other standard diving dress, preparing to explore the wreck of the RMS Lusitania, 1935.

Although various atmospheric suits had been developed during the Victorian era, none of these suits had been able to overcome 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 200 fathoms (1,200 ft; 370 m), where the pressure was 520 psi (35 atm), although this was never proven.[12]

Luciana Civico ascending from the dive of the depth record at 82 meters on 11 November 1962 in the vicinity of Capo Miseno in the Gulf of Pozzuoli tightens the pincer of the diving suit operated by the s. Lieutenant Benito Velardi

In 1930, Peress revealed the Tritonia suit.[13] 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 123 m (404 ft) 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 90 m (300 ft). In October 1935 Jarret made a successful deep dive to more than 90 m (300 ft) on the wreck of the RMS Lusitania off south Ireland, followed by a shallower dive to 60 metres (200 ft) in the English Channel in 1937 after which, due to lack of interest, the Tritonia suit was retired.

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.[12]

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.[12][14][15] 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.[16]

JIM suit in Naval Undersea Museum

The first JIM suit was completed in November 1971 and underwent trials aboard HMS Reclaim in early 1972. In 1976, the JIM suit set a record for the longest working dive below 490 feet (150 m), lasting five hours and 59 minutes at a depth of 905 feet (276 m). The first JIM suits were constructed from cast magnesium for its high strength-to-weight ratio and weighed approximately 1,100 pounds (500 kg) in air including the diver. They were 6 feet 6 inches (1.98 m) in height and had a maximum operating depth of 1,500 feet (460 m). The suit had a positive buoyancy of 15 to 50 pounds-force (67 to 222 N). Ballast was attached to the suit's front and could be jettisoned from within, allowing the operator to ascend to the surface at approximately 100 feet per minute (30 m/min).[17] The suit also incorporated a communication link and a jettisonable umbilical connection. The original JIM suit had eight annular oil-supported universal joints, one in each shoulder and lower arm, and one at each hip and knee. 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.[18] Operations in arctic conditions with water temperatures of −1.7 °C for over 5 hours were successfully carried out using woolen thermal protection and neoprene boots. In 30 °C water the suit was reported to be uncomfortably hot during heavy work.[19]

A JIM suit on display at the Royal Navy Submarine Museum, Gosport

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, this allowed the operator a much-improved 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.[19]

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 1,000 feet (300 m). 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 6 feet 3 inches (1.91 m) 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 2,000 feet (610 m).[20]

WASP at the OSEL Testing tank Great Yarmouth, UK

The WASP atmospheric diving system is part way 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 2,300 feet (700 m)[2]

WASP is 84 inches (2.1 m) high, 42 inches (1.1 m) wide, and 34 inches (0.86 m) front to back. Ballasted weight in air approximately 2,200 pounds (1,000 kg), for neutral buoyancy in water, but buoyancy can be increased by up to 35 pounds (16 kg) during operation, and ballast can be jettisoned in an emergency. WASP is transported on a support frame.[2]