''Byford Dolphin'' was a

semi-submersible Semi-submersible may refer to a self-propelled vessel, such as: * Heavy-lift ship, which partially submerge to allow their cargo (another ship) to float into place for transport *Narco-submarine, some of which remained partially on the surface * ...

, column-stabilised

drilling rig A drilling rig is an integrated system that drills wells, such as oil or water wells, or holes for piling and other construction purposes, into the earth's subsurface. Drilling rigs can be massive structures housing equipment used to drill wat ...

operated by

Dolphin Drilling Dolphin Drilling Holdings Limited is an offshore drilling rig company headquartered in Aberdeen, Scotland, United Kingdom with its main subsidiary Dolphin Drilling AS located in Sandnes, Norway. Until 2019, Dolphin Drilling had its headquarters ...

, a Fred Olsen Energy subsidiary. It drilled seasonally for various companies in the United Kingdom, Danish and Norwegian sectors of the

North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian S ...

. It was registered in

Hamilton, Bermuda The City of Hamilton, in Pembroke Parish, is the territorial capital of the British Overseas Territory of Bermuda. It is the territory's financial centre and a major port and tourist destination. Its population of 854 (2016) is one of the sm ...

. The rig suffered some serious accidents, most notably an

explosive decompression Uncontrolled decompression is an unplanned drop in the pressure of a sealed system, such as an aircraft cabin or hyperbaric chamber, and typically results from human error, material fatigue, engineering failure, or impact, causing a pressure vesse ...

in 1983 that killed four divers and one dive tender, as well as badly injured another dive tender. As of September 2018, the Byford Dolphin was laid up in

Rosfjord The Rosfjord or Rosfjorden is a fjord in Lyngdal municipality in Agder county, Norway. The long fjord runs from the town of Lyngdal (town), Lyngdal to the North Sea in the south. The Austad peninsula lies on the east side of the fjord, with the ...

Norway Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and t ...

, near Agnefest.

Description

Built as ''Deep Sea Driller'', it was the ''first-of-class'' in the highly successful Aker H-3 series, designed by Aker Group completed at the Aker Verdal shipyard in 1974. ''Byford Dolphin'' had a length overall of , breadth of and depth of . It had a maximum drilling depth of , and it could operate at a water depth of . As a drilling rig, ''Byford Dolphin'' was equipped with advanced drilling equipment and originally met strict levels of certification under Norwegian law, though in later years, banned from Norwegian waters. ''Byford Dolphin'' was able to maneuver with its own

engine An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy. Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power gen ...

s (to counter

drift Drift or Drifts may refer to: Geography * Drift or ford (crossing) of a river * Drift, Kentucky, unincorporated community in the United States * In Cornwall, England: ** Drift, Cornwall, village ** Drift Reservoir, associated with the village ...

and ocean currents), but for long-distance relocation, it must be moved by specialist

tugboat A tugboat or tug is a marine vessel that manoeuvres other vessels by pushing or pulling them, with direct contact or a tow line. These boats typically tug ships in circumstances where they cannot or should not move under their own power, su ...

Accidents and incidents

''Deep Sea Driller'' accident

On 1 March 1976, the rig ran aground during transit from a block in the North Sea to

Bergen Bergen (), historically Bjørgvin, is a city and municipality in Vestland county on the west coast of Norway. , its population is roughly 285,900. Bergen is the second-largest city in Norway. The municipality covers and is on the peninsula of ...

. All crew were evacuated, but six people died when they fell out of their boats.

Diving bell accident

On Saturday, 5 November 1983, at 4:00 a.m., while drilling in the

Frigg gas field Frigg gas field is a natural gas field on Norwegian block 25/1 in the North Sea, on the boundary between the United Kingdom and Norway. The field is named after the goddess Frigg. King Olav V of Norway officially opened production on 8 May 1978. P ...

in the Norwegian sector of the

, four divers were in a

diving chamber 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 ...

system on the rig's deck that was connected by a trunk (a short passage) to a

diving bell 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 c ...

. The divers were Edwin Arthur Coward (British, 35 years old), Roy P. Lucas (British, 38), Bjørn Giæver Bergersen (Norwegian, 29) and Truls Hellevik (Norwegian, 34). They were assisted by two dive tenders, William Crammond (British, 32) and Martin Saunders. Byford Dolphin Accident

Just prior to the event, decompression chambers 1 and 2 (along with a third chamber which was not in use at the time) were connected via a trunk to a diving bell. The connection made by the trunk was kept sealed by a clamp operated by Crammond and Saunders, who were experienced divers. Coward and Lucas were resting in chamber 2 at a pressure of 9 atm. The diving bell with Bergersen and Hellevik had just been winched up after a dive and joined to the trunk. Leaving their wet equipment in the trunk, the two divers climbed through the trunk into chamber 1. The normal procedure would have been: # Close the diving bell door, which would have been open to the trunk. # Slightly increase the pressure in the diving bell to seal the bell door tightly. # Close the chamber 1 door, which was also open to the trunk. # Slowly depressurize the trunk until it reached a pressure of 1 atm. # Open the clamp to separate the diving bell from the chamber system. The first two steps had been completed when, for an unknown reason, Crammond opened the clamp that was keeping the trunk sealed before Diver 4 (Hellevik) could close the door to the chamber. This resulted in the chamber being explosively decompressed from a pressure of nine atmospheres to the one atmosphere of the unsealed chamber system. Air rushed out of the chamber system with tremendous force, jamming the interior trunk door and pushing the bell away, striking the two tenders. All four divers were killed; one of the tenders, Crammond, was killed, while Saunders was severely injured.

Medical findings

Medical investigations were carried out on the remains of the four divers. The most notable finding was the presence of large amounts of fat in large

arteries An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the pu ...

and

vein Veins are blood vessels in humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated b ...

s and in the cardiac chambers, as well as intravascular fat in organs, especially the

liver The liver is a major Organ (anatomy), organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of proteins and biochemicals necessary for ...

. This fat was unlikely to be

embolic An embolism is the lodging of an embolus, a blockage-causing piece of material, inside a blood vessel. The embolus may be a blood clot (thrombus), a fat globule ( fat embolism), a bubble of air or other gas (gas embolism), amniotic fluid ( amni ...

, but must have

precipitated In an aqueous solution, precipitation is the process of transforming a dissolved substance into an insoluble solid from a super-saturated solution. The solid formed is called the precipitate. In case of an inorganic chemical reaction leading ...

from the blood ''

in situ ''In situ'' (; often not italicized in English) is a Latin phrase that translates literally to "on site" or "in position." It can mean "locally", "on site", "on the premises", or "in place" to describe where an event takes place and is used in ...

''. The autopsy suggested that rapid bubble formation in the blood denatured the

lipoprotein A lipoprotein is a biochemical assembly whose primary function is to transport hydrophobic lipid (also known as fat) molecules in water, as in blood plasma or other extracellular fluids. They consist of a triglyceride and cholesterol center, sur ...

complexes, rendering the

lipid Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include ...

s insoluble. The blood of the three divers left intact inside the chambers likely boiled instantly, stopping their circulation. The fourth diver was dismembered and mutilated by the blast forcing him out through the partially blocked doorway and would have died instantly. Coward, Lucas, and Bergersen were exposed to the effects of explosive decompression and died in the positions indicated by the diagram. Investigation by

forensic pathologist Forensic pathology is pathology that focuses on determining the cause of death by examining a corpse. A post mortem examination is performed by a medical examiner or forensic pathologist, usually during the investigation of criminal law cases ...

s determined that Hellevik, being exposed to the highest pressure gradient and in the process of moving to secure the inner door, was forced through the crescent-shaped opening measuring long created by the jammed interior trunk door. With the escaping air and pressure, it included bisection of his thoracoabdominal cavity, which resulted in fragmentation of his body, followed by expulsion of all of the internal

organs In biology, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to act together in a f ...

of his chest and abdomen, except the trachea and a section of small intestine, and of the thoracic spine. These were projected some distance, one section being found vertically above the exterior pressure door.

Investigation

The committee investigating the accident concluded that it was caused by human error on the part of the dive tender who opened the clamp. The trunk door had a center hinge design, similar to a

butterfly valve A butterfly valve is a valve that isolates or regulates the flow of a fluid. The closing mechanism is a disk that rotates. Principle of operation Operation is similar to that of a ball valve, which allows for quick shut off. Butterfly valves ...

disc, and the door was rotated too far to the left, causing the rim of the interior hatch to lodge on the door opening. This left a crescent shaped opening, similar to a manhole cover left ajar but held in place. This created an opening that was 24 inches across horizontally. It is not clear whether the tender who opened the clamp before the trunk was depressurized did so by order of his supervisor, on his own initiative, or because of miscommunication. At the time, the only communication the tenders on the outside of the chamber system had was through a bullhorn attached to the wall surface; with heavy noise from the rig and sea, it was hard to listen in on what was going on. Fatigue from many hard hours of work also took its toll among the divers, who often worked 16-hour shifts. This incident was also attributed to engineering failure. The obsolete ''Byford Dolphin'' diving system, dating from 1975, was not equipped with

fail-safe In engineering, a fail-safe is a design feature or practice that in the event of a specific type of failure, inherently responds in a way that will cause minimal or no harm to other equipment, to the environment or to people. Unlike inherent safe ...

hatches, outboard pressure gauges, and an interlocking mechanism, which would have prevented the trunk from being opened while the system was under pressure. Prior to the accident, Norske Veritas had issued the following rule for certification: "Connecting mechanisms between bell and chambers are to be so arranged that they cannot be operated when the trunk is pressurized", therefore requiring such systems to have fail-safe seals and interlocking mechanisms. One month after the accident, Norske Veritas and the Norwegian oil directorate made the rule final for all bell systems. Among others, former crew members of ''Byford Dolphin'' and NOPEF (a Norwegian oil and petro-chemical union) have come forward and claimed the investigation was a

cover-up A cover-up is an attempt, whether successful or not, to conceal evidence of wrongdoing, error, incompetence, or other embarrassing information. Research has distinguished personal cover-ups (covering up one's own misdeeds) from relational co ...

. They claimed that the commission investigating the accident did not mention in their report the irresponsible dispensations on vital equipment requested by Comex and authorized by the diving section to the Norwegian Petroleum Directorate, which played a vital role in the accident's occurrence. They also alleged the accident was due to a lack of proper equipment, including clamping mechanisms equipped with interlocking mechanisms (which would be impossible to open while the chamber system was still under pressure), outboard pressure gauges, and a safe communication system, all of which had been held back because of dispensations by the Norwegian Petroleum Directorate.

Lawsuit

The North Sea Divers Alliance, formed by early North Sea divers and the relatives of those killed, continued to press for further investigation and, in February 2008, obtained a report that indicated the real cause was faulty equipment. Clare Lucas, daughter of Roy Lucas, said: "I would go so far as to say that the Norwegian Government murdered my father because they knew that they were diving with an unsafe decompression chamber." The families of the divers eventually received compensation for the damages from the Norwegian government 26 years after the incident.

Other incidents

On 17 April 2002, a 44-year-old Norwegian worker on the rig was struck on the head and killed in an

industrial accident A work accident, workplace accident, occupational accident, or accident at work is a "discrete occurrence in the course of work" leading to physical or mental occupational injury. According to the International Labour Organization (ILO), more tha ...

. The accident resulted in ''Byford Dolphin'' losing an exploration contract with Statoil, which expressed concerns with the rig's operating procedures. The incident cost the company millions of dollars in lost income.