Standard diving dress, also known as hard-hat or copper hat equipment, deep sea diving suit or heavy gear, is a type of diving suit that was formerly used for all relatively deep underwater work that required more than breath-hold duration, which included marine salvage, civil engineering, pearl shell diving and other commercial diving work, and similar naval diving applications. Standard diving dress has largely been superseded by lighter and more comfortable equipment.
Surface-supplied diving is a mode of underwater diving using equipment supplied with breathing gas through a diver's umbilical from the surface, either from the shore or from a diving support vessel, sometimes indirectly via a diving bell. This is different from scuba diving, where the diver's breathing equipment is completely self-contained and there is no essential link to the surface. The primary advantages of conventional surface supplied diving are lower risk of drowning and considerably larger breathing gas supply than scuba, allowing longer working periods and safer decompression. Disadvantages are the absolute limitation on diver mobility imposed by the length of the umbilical, encumbrance by the umbilical, and high logistical and equipment costs compared with scuba. The disadvantages restrict use of this mode of diving to applications where the diver operates within a small area, which is common in commercial diving work.
Saturation diving is diving for periods long enough to bring all tissues into equilibrium with the partial pressures of the inert components of the breathing gas used. It is a diving mode that reduces the number of decompressions divers working at great depths must undergo by only decompressing divers once at the end of the diving operation, which may last days to weeks, having them remain under pressure for the whole period. A diver breathing pressurized gas accumulates dissolved inert gas used in the breathing mixture to dilute the oxygen to a non-toxic level in the tissues, which can cause potentially fatal decompression sickness if permitted to come out of solution within the body tissues; hence, returning to the surface safely requires lengthy decompression so that the inert gases can be eliminated via the lungs. Once the dissolved gases in a diver's tissues reach the saturation point, however, decompression time does not increase with further exposure, as no more inert gas is accumulated.
A diving bell is a rigid chamber used to transport divers from the surface to depth and back in open water, usually for the purpose of performing underwater work. The most common types are the open-bottomed wet bell and the closed bell, which can maintain an internal pressure greater than the external ambient. Diving bells are usually suspended by a cable, and lifted and lowered by a winch from a surface support platform. Unlike a submersible, the diving bell is not designed to move under the control of its occupants, or to operate independently of its launch and recovery system.
A diving support vessel is a ship that is used as a floating base for professional diving projects. Basic requirements are the ability to keep station accurately and reliably throughout a diving operation, often in close proximity to drilling or production platforms, for positioning to degrade slowly enough in deteriorating conditions to recover divers without excessive risk, and to carry the necessary support equipment for the mode of diving to be used.
Byford Dolphin was a semi-submersible, column-stabilised drilling rig operated by Dolphin Drilling, a subsidiarity of Fred Olsen Energy. Byford Dolphin was registered in Hamilton, Bermuda, and drilled seasonally for various companies in the British, Danish, and Norwegian sectors of the North Sea. In 2019, Dolphin scrapped the rig.
A diving chamber is a vessel for human occupation, which may have an entrance that can be sealed to hold an internal pressure significantly higher than ambient pressure, a pressurised gas system to control the internal pressure, and a supply of breathing gas for the occupants.
Diver rescue, usually following an accident, is the process of avoiding or limiting further exposure to diving hazards and bringing a diver to a place of safety. A safe place generally means a place where the diver cannot drown, such as a boat or dry land, where first aid can be administered and from which professional medical treatment can be sought. In the context of surface supplied diving, the place of safety for a diver with a decompression obligation is often the diving bell.
Commercial offshore diving, sometimes shortened to just offshore diving, generally refers to the branch of commercial diving, with divers working in support of the exploration and production sector of the oil and gas industry in places such as the Gulf of Mexico in the United States, the North Sea in the United Kingdom and Norway, and along the coast of Brazil. The work in this area of the industry includes maintenance of oil platforms and the building of underwater structures. In this context "offshore" implies that the diving work is done outside of national boundaries. Technically it also refers to any diving done in the international offshore waters outside of the territorial waters of a state, where national legislation does not apply. Most commercial offshore diving is in the Exclusive Economic Zone of a state, and much of it is outside the territorial waters. Offshore diving beyond the EEZ does also occur, and is often for scientific purposes.
There are several categories of decompression equipment used to help divers decompress, which is the process required to allow divers to return to the surface safely after spending time underwater at higher ambient pressures.
The Star Canopus diving accident was an incident in Scotland in November 1978 that killed two British commercial divers. During a routine dive beside the Beryl Alpha platform in the North Sea, the diving bell of the diving support vessel MS Star Canopus was lost when its main lift wire, life support umbilical, and guide wires were severed by an anchor chain of the semi-submersible Haakon Magnus. The bell dropped to the seabed at a depth of over 100 metres (330 ft). Its two occupants, 25-year-old Lothar Michael Ward and 28-year-old Gerard Anthony "Tony" Prangley, were unable to release the bell's drop weight in order to return to the surface because it was secured to the bell frame with secondary locking pins. Since there was not a bell stage to keep the bottom door of the bell off the seabed, the divers could not exit the bell to release the pins. Despite the efforts of three rescue vessels – Intersub 4, Tender Carrier, and Uncle John – the bell was not recovered for over thirteen hours, by which time Ward and Prangley had died of hypothermia and drowning.
The Stena Seaspread diving accident occurred on 21 January 1981, when a diving bell containing two divers had its umbilical cord severed. Both divers were rescued.
Surface supplied diving skills are the skills and procedures required for the safe operation and use of surface-supplied diving equipment. Besides these skills, which may be categorised as standard operating procedures, emergency procedures and rescue procedures, there are the actual working skills required to do the job, and the procedures for safe operation of the work equipment other than diving equipment that may be needed.
Surface-supplied diving equipment (SSDE) is the equipment required for surface-supplied diving. The essential aspect of surface-supplied diving is that breathing gas is supplied from the surface, either from a specialised diving compressor, high-pressure gas storage cylinders, or both. In commercial and military surface-supplied diving, a backup source of surface-supplied breathing gas should always be present in case the primary supply fails. The diver may also wear a bailout cylinder which can provide self-contained breathing gas in an emergency. Thus, the surface-supplied diver is less likely to have an "out-of-air" emergency than a scuba diver using a single gas supply, as there are normally two alternative breathing gas sources available. Surface-supplied diving equipment usually includes communication capability with the surface, which improves the safety and efficiency of the working diver.
Diving hazards are the agents or situations that pose a threat to the underwater diver or their equipment. Divers operate in an environment for which the human body is not well suited. They face special physical and health risks when they go underwater or use high pressure breathing gas. The consequences of diving incidents range from merely annoying to rapidly fatal, and the result often depends on the equipment, skill, response and fitness of the diver and diving team. The classes of hazards include the aquatic environment, the use of breathing equipment in an underwater environment, exposure to a pressurised environment and pressure changes, particularly pressure changes during descent and ascent, and breathing gases at high ambient pressure. Diving equipment other than breathing apparatus is usually reliable, but has been known to fail, and loss of buoyancy control or thermal protection can be a major burden which may lead to more serious problems. There are also hazards of the specific diving environment, and hazards related to access to and egress from the water, which vary from place to place, and may also vary with time. Hazards inherent in the diver include pre-existing physiological and psychological conditions and the personal behaviour and competence of the individual. For those pursuing other activities while diving, there are additional hazards of task loading, of the dive task and of special equipment associated with the task.
The following outline is provided as an overview of and topical guide to underwater diving:
A diving team is a group of people who work together to conduct a diving operation. A characteristic of professional diving is the specification for minimum personnel for the diving support team. This typically specifies the minimum number of support team members and their appointed responsibilities in the team based on the circumstances and mode of diving, and the minimum qualifications for specified members of the diving support team. The minimum team requirements may be specified by regulation or code of practice. Some specific appointments within a professional dive team have defined competences and registration may be required.
Human factors in diving equipment design are the influences of the interactions between the user and equipment in the design of diving equipment and diving support equipment. The underwater diver relies on various items of diving and support equipment to stay alive, healthy and reasonably comfortable and to perform planned tasks during a dive.
The 1973 Mount Gambier cave diving accident was a scuba diving incident on 28 May 1973 at a flooded sinkhole known as "The Shaft" near Mount Gambier in South Australia. The incident claimed the lives of four recreational scuba divers: siblings Stephen and Christine M. Millott, Gordon G. Roberts, and John H. Bockerman. The four divers explored beyond their own planned limits, without the use of a guideline, and subsequently became lost, eventually exhausting their breathing air and drowning, with their bodies all recovered over the next year. To date, they are the only known fatalities at the site. Four other divers from the same group survived.
