Ed Hammond, Robert Kelly, Lothar Michael Ward, Gerard Anthony "Tony" Prangley
Outcome
Deaths of Ward and Prangley
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 (330ft). 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.[1][2][3][4]
On 26 November 1978 the Diving Support Vessel Star Canopus was dynamically positioned on the northeast side of the Beryl Alpha platform conducting diving operations. 334 feet (102m) below, Michael Ward was working for Northern Divers about 60 feet (18m) off the seabed trying to connect a 6-inch (150mm) flow line to a riser flange protruding from the side of the concrete platform.[citation needed]
Oil production had declined that year,[5] and with winter conditions upon them, subsea work had fallen behind schedule.[6] There was "a lot of catching up to do", Martin Dane, the Contracts Manager for Northern Divers would say later,[7] and Mobil Oil, like many operators, decided to allow the diving program to continue through the winter months to take advantage of available weather windows.
Earlier that evening, London Weather Center had predicted 40-knot gusts between 18:00 and midnight.[8] That forecast proved to be correct. At 2030, and again at 2245, squalls reaching those speeds moved in and blew the Canopus off location.[9] Shortly thereafter, Captain Roy Forsyth terminated diving operations.[10] But when the 12-hour shift change occurred at midnight, weather conditions had calmed. Coming on duty, Supervisor Robert Kelly was instructed by diving superintendent Ed Hammond to continue with the dive program due to improved conditions.[11]
The weather forecast now predicted that there would be a change in wind direction from west to north, and that conditions "would worsen later in the day" with wind speeds gusting to 35 knots.[12] The Canopus was only a year old, and although it represented the latest and best technology of that era, the limits of her dynamic positioning system were 18–20 knots with the wind hitting her broadside.[13]
Accident and recovery
Position of the Canopus prior to the accident, with Ward locked out of the bell
Prior to the accident, the wind-speed indicator was fluctuating between 15–20 knots (28–37km/h). Standing alongside the Beryl platform, near where the Canopus would be commencing work, was the Haakon Magnus, a Norwegian semi-submersible platform, with her massive anchor chains extended.[citation needed] Kelly determined the weather was suitable for diving and, at 0240, he launched the bell with Tony Prangley and Michael Ward inside.[14]
At 0312, Ward locked out and found the pipe flange protruding from the wall of the platform base. Eight minutes later, Captain Forsyth called Kelly on the ship's intercom to alert him that a squall was approaching on the ship's radar.[15] Kelly ordered Ward back to the bell where he sat for the next 40 minutes. At 0400 Ward was back on the job. Then, at 0545, the wind suddenly shifted directions and began blowing from the north at a speed of 40 knots, hitting the Canopus on her beam, and overpowering her dynamic positioning (DP) system. It was a sustained blow, the Contracts Manager would later testify:
When this wind arrived, it arrived really without any warning and it was not like a sudden gust of wind or a passing squall which then died down; it started blowing suddenly at 40 knots and remained at that level for a considerable period of time thereafter. It was a very strange occurrence, to say the least.[16]
In dive control, Supervisor Kelly was at the control panel when an amber warning light and the 'Dive Alert' alarm were activated. Captain Forsyth's ordered the divers to return to the bell.[17] Kelly relayed the message to Ward who stopped what he was doing and swam back to the bell. In the trunking he took off his helmet as Prangley stacked his umbilical.
The Canopus being blown into the path of the Haakon Magnus anchor chain
On the surface, the force of the wind had blown the Canopus sideways against the platform overhang, snapping off the ship's mast which came crashing down onto the deck. At the same time, the wind was driving the ship backwards towards the Haakon Magnus. Captain Forsyth quickly took the ship off DP and tried to swing the bow outboard to keep the vessel from grounding on the submerged pontoons of the Magnus. Then he pressed the 'Dive Abort' alarm and called dive control.[citation needed]
In dive control, Kelly was waiting for Prangley and Ward to seal the bell when the red 'Dive Abort' indicator suddenly lit up. Captain Forsyth again contacted Kelly at the control panel, restating the need for the divers to return to the bell.[18] But when Kelly called down to the bell, he discovered that Prangley was having difficulty pulling in Ward's umbilical; it was snagged on something outside the bell. He did not know on what, but now there was no way to shut the inside hatch until the umbilical was cleared. Ward wanted to lock out to fix the problem, but Kelly forbade him from doing so. Instead, he told Ward to throw the dive hat out of the bell, then pull in the umbilical. But when this was tried, the umbilical remained snagged.[19]
Meanwhile, Kelly received another urgent message from Captain Forsyth asking if he had started recovering the bell yet.[20] Kelly explained the delay and said he would notify the bridge when he started the recovery. He told the divers to stop what they were doing, and to cut the hose, and be quick about it.[21] Several minutes later, as the bell smashed against the base of the platform, Prangley and Ward got a seal and notified topside.
In dive control, Kelly was watching his two divers on the video monitor while the bell was being raised. Prangley was calling out the depth every 10 metres (33ft). When the bell was 30 metres (98ft) from the surface, Prangley suddenly stood up, waved his fist shoulder high, and shouted, "All stop."[22] On the monitor, he appeared to be listening to something.
Supervisor Kelly did as he was told, and from dive control, he had a clear view of the moonpool and could see that something was wrong. The bell umbilical and clump weight guide wires were not hanging straight down through the moonpool; they were leaning towards the bow of the ship. Furthermore, the trolley that the wires were hanging from was violently shaking and vibrating.[23] Kelly then lost video feed of the divers. The Star Canopus had been blown across the path of a Haakon Magnus anchor chain, completely severing all connections to the bell, including the life-support umbilical, the main lift wire, and the clump weight/guide wire recovery system. In that instant, the bell, with Prangley and Ward inside, began plummeting to the seabed below.
Both divers survived the 294-foot (90m) fall. With their hot-water supply disconnected, the bell's internal temperature began to drop rapidly. If rescuers did not arrive soon, the divers' only recourse would be to release the drop weight to surface the bell. However, Prangley and Ward could not release the weight because it was externally secured to the bell frame with a set of "secondary locking pins".[24] Because the bell was not equipped with a stage to keep the bottom hatch out of the mud, Prangley and Ward had no way to get out to release them. The bell was also not equipped with a strobe flasher to help rescue divers find it in the dark. In addition, the crew of the Canopus had removed the bell transponder some time before the dive.[25]
Recovery
With a storm occurring on the surface, it took rescuers more than thirteen hours to recover the stricken bell to the deck of the Canopus. By that time, Ward had died of hypothermia and Prangley had drowned.[lower-alpha 1]
Notes
↑ Although Prangley was also suffering from hypothermia, his death was ruled as a drowning. When the bell was initially raised off the seabed, he fell out of the trunking and floated to the surface. Source: Prangley/Ward FAI Transcript p. 152.
Related Research Articles
Surface-supplied diving is diving using equipment supplied with breathing gas using 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 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 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.
Diver communications are the methods used by divers to communicate with each other or with surface members of the dive team. In professional diving, diver communication is usually between a single working diver and the diving supervisor at the surface control point. This is considered important both for managing the diving work, and as a safety measure for monitoring the condition of the diver. The traditional method of communication was by line signals, but this has been superseded by voice communication, and line signals are now used in emergencies when voice communications have failed. Surface supplied divers often carry a closed circuit video camera on the helmet which allows the surface team to see what the diver is doing and to be involved in inspection tasks. This can also be used to transmit hand signals to the surface if voice communications fails. Underwater slates may be used to write text messages which can be shown to other divers, and there are some dive computers which allow a limited number of pre-programmed text messages to be sent through-water to other divers or surface personnel with compatible equipment.
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.
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, 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 is often 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.
An emergency ascent is an ascent to the surface by a diver in an emergency. More specifically, it refers to any of several procedures for reaching the surface in the event of an out-of-air emergency, generally while scuba diving.
The Wildrake diving accident was an incident in Scotland in August 1979 that killed two American commercial divers. During a routine dive in the East Shetland Basin of the North Sea, the diving bell of the diving support vessel MS Wildrake became separated from its main lift wire at a depth of over 160 metres (520 ft). Although the bell was eventually recovered by Wildrake, its two occupants, 32-year-old Richard Arthur Walker and 28-year-old Victor Francis "Skip" Guiel Jr., died of hypothermia. The accident resulted in extensive subsequent litigation and led to important safety changes in the diving industry.
The Drill Master diving accident was an incident in Norway in January 1974 that claimed the lives of two Ocean Systems commercial divers. During a two-man dive from the North Sea rig Drill Master, the diving bell's drop weight was accidentally released, causing the bell to surface from a depth of 320 feet (98 m) with its bottom door open and drag the diver working outside through the water on his umbilical. The two divers, Per Skipnes and Robert John Smyth, both died from rapid decompression and drowning. The accident was caused by instructions aboard Drill Master which had not been updated when the bell system was modified and which stated that a valve should be closed during the dive which should have been open. Skipnes' body was never recovered.
The Waage Drill II diving accident occurred in the North Sea off Scotland on 9 September 1975, when two divers died of heatstroke after the chamber they were in was inadvertently pressurised with helium gas.
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.
The Venture One diving accident occurred on 10 May 1977, three miles east of the North Cormorant oil field in the North Sea, when a diver drowned while working at a depth of about 500 feet (150 m).
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.
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:
Diving support equipment is the equipment used to facilitate a diving operation. It is either not taken into the water during the dive, such as the gas panel and compressor, or is not integral to the actual diving, being there to make the dive easier or safer, such as a surface decompression chamber. Some equipment, like a diving stage, is not easily categorised as diving or support equipment, and may be considered as either.
Diving procedures are standardised methods of doing things that are commonly useful while diving that are known to work effectively and acceptably safely. Due to the inherent risks of the environment and the necessity to operate the equipment correctly, both under normal conditions and during incidents where failure to respond appropriately and quickly can have fatal consequences, a set of standard procedures are used in preparation of the equipment, preparation to dive, during the dive if all goes according to plan, after the dive, and in the event of a reasonably foreseeable contingency. Standard procedures are not necessarily the only courses of action that produce a satisfactory outcome, but they are generally those procedures that experiment and experience show to work well and reliably in response to given circumstances. All formal diver training is based on the learning of standard skills and procedures, and in many cases the over-learning of the skills until the procedures can be performed without hesitation even when distracting circumstances exist. Where reasonably practicable, checklists may be used to ensure that preparatory and maintenance procedures are carried out in the correct sequence and that no steps are inadvertently omitted.
Last Breath is a 2019 British documentary film directed by Richard da Costa and Alex Parkinson. It relates the story of a serious saturation diving accident in 2012, when diver Chris Lemons had his umbilical cable severed and became trapped around 100 metres (330 ft) under the sea without heat or light, and with only the small amount of breathing gas in his backup tank.
↑ "Trapped divers die as rescue attempt failed". The Scotsman. 27 November 1978.
↑ "Development of the oil and gas resources of the United Kingdom (Brown Book)". Department of Energy: 31. 1980.
↑ Transcript of Evidence in Fatal Accident Inquiry into the deaths of Gerard Anthony Prangley and Lothar Michael Ward (Report). November 1979. pp.158, 180.
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