DSV Seaway Pelican – Random Chapter 33 Excerpts
“A wonderful bird is the Pelican. His beak can hold more than his belly can.” – Dixon Lanier Merritt
During the first months in the new house at Minde, I had several calls offering inshore diving work. Even though I desperately needed income, I had to decline them all, as leaving Bergen for weeks, let alone days at a time, would be impossible. The hotel was taking up every waking minute of my day. I was determined to finish as much as possible before the offshore saturation diving season started again in the spring.
Spring arrived early in 1993 for Stolt Nielsen Seaway (SNS), and the summons for offshore work came at the end of February. On 02 March, SNS sent me to the Ekofisk field to work on the Dive Support Vessel (DSV) Seaway Pelican, a world-class DP III dive vessel that would become my primary offshore home for the following seven years. Employment on the Seaway Pelican would last until the end of October 1999.
It was my first time on the Seaway Pelican, built at Framnæs Mek.Verk., Sandefjord, Norway, in 1985. After only spending a few hours on board, I realised she was the perfect diving vessel, tailored for efficiency, safety, and the specific needs of highly demanding underwater operations. All the necessary amenities, equipment, and systems for diving operations were in prime condition. The fact that everything appeared to function seamlessly spoke volumes about the ship’s maintenance and professional operation. Everything ran flawlessly on the four thousand seven hundred and sixty-three gross tonne vessel measuring ninety-three point two metres in length and eighteen metres in width.
Looking around, I discovered it was similar in layout but slightly different from the other two SNS diving ships I had worked aboard. Nineteen single and forty-three double cabins could accommodate one hundred and five crewmembers. Generally similar in layout to the eight-metre-longer DSV Seaway Condor; however, the Seaway Pelican was double-skin-hulled, so it was much quieter. The main aft deck was slightly smaller but had a one hundred and twenty-ton hydraulic boom crane in double fall, sixty tons in single fall on the starboard side, four auxiliary deck cranes, and Kongsberg K-POS DP 21 & DP11-BU (emergency bridge) systems to hold the vessel in place during diving operations.
The DP computers received positioning data from three Differential Global Positioning Systems (DGPS), two High Precision Acoustic Positioning (HiPAP) 351 systems, two taught wires and a fan beam interface. The gym and laundry rooms were located below decks in the bowels at the boat’s bow. The moonpools and saturation chambers were in the vessel’s centre. The saturation system was rated for two hundred and eighty-four metres and could hold eighteen men. There were three six-man living chambers, two TUPs and two three-person bells. In addition, there were two sixteen-man capacity Self-Propelled Hyperbaric Lifeboats (SPHLs). The hyperbaric lifeboats on the starboard and port sides were interconnected via tunnel trunkings to the sat system below deck.
One Observation (OBS) ROV spread was permanently integrated on board, and mobilising a working-class ROV spread was optional when required; the working-class Triton XL ROV was needed so often that the spread was more or less a permanent onboard feature. Since the ship mainly operated in the North Sea, most of the crew were Norwegian and British, and many had backgrounds in the fishing industry. Like the ship they were on, the men were versatile and extremely capable.
When it was time to start working, I looked over the chamber system before entering. It was an extensive system with a modern gas reclaim system, saving the clients and company a lot of money. As I entered the decompression chamber with my two teammates, I was impressed by the systematic layout of the modern chamber. We were blown down to our living depth of sixty-five metres. Once down at depth, we crawled through the chamber’s connecting trunkings into our dedicated living chamber and met the members of the three other teams who had been at depth for a week. I immediately noted the differences from the earlier systems I’d been in. The equipment and medical hatches were quite large, the wet pots were more spacious, and not least, all the chamber’s trunking doors were modern and of a much lighter weight metal.
The job was a critical repair to be performed as soon as possible. Four teams would work 24/7, rotating six to six-and-a-half-hour locked-out shifts on the seabed to rectify the problem. All twelve of us divers received in-depth briefings, so we were prepared and eager to start when it was our team’s turn to enter one of the system’s two dive bells and take our elevator down to work in the basement.
Below us lay a twelve-inch diameter, eight-hundred bar rated water ejection pipeline used to maintain pressure in the oil reservoir in the subterranean strata deep below the seabed. During a routine pipeline inspection, a high-pressure jet of water had severely damaged an OBS ROV a few weeks earlier while it was hovering just above the pipeline. The high-pressure, high-flow jettisoned water came from a ten-centimetre crack in the pipeline, probably caused by a ship’s anchor.
Although the ROV was rendered inoperative, the ROV pilot and crew managed to salvage the vehicle as its tether was still attached to the functioning Tether Management System (TMS). The TMS is similar to a garage and tethers the ROV in and out from a reel. The TMS is lowered and raised from the ship utilising a lift wire spooled on and off a ROV winch on the ship’s deck. The wire includes power and communication cabling in its core. The winch drum-to-winch frame interface has an intricate slip ring system providing uninterrupted high-voltage electrical power, video and data transmission via fibre.
The dive teams would cut out the cracked, damaged pipeline section and then replace the removed pipe pup piece with a clever sleeve arrangement. The crew on the platform, who controlled the high-pressure water delivery, turned off the water pumps, manually isolating the water flow and remotely shutting the wellhead trees well injection valves.
Since the pipeline had been trenched (buried) a metre below the seabed, we first had to remove over a hundred cubic meters of sand to gain access. Therefore, a metal cofferdam was placed over the work site to hinder the sand from backfilling the excavated crater. The cofferdam looked like a rectangular shoebox measuring seven by four metres with five-metre high sidewalls, without a lid or a bottom. The lower ends of the short sides had cut-outs shaped like upside-down U’s that would fit over the pipe and sink in as we removed the sand.
Once the shoebox landed in the required position on the seabed with the correct orientation, we started using an eight-inch diameter, twelve-meter-long airlift to suck the sand away. As the sand was gradually removed, the cofferdam slowly sank, ending up firmly positioned over the broken pipe with the top of its walls protruding just a metre above the seabed. The excavation had taken over seventy hours, but now we were ready to start cutting.
A hydraulic-driven Wachs cutter was lowered down to the job site by the Seaway Pelican’s crane, which we clamped around the pipeline. Cutting the pipe was dangerous work; we were careful always to maintain vigilance, keeping our limbs, fingers, umbilicals and hydraulic hoses clear of the rotating blades and avoiding the razor-sharp swarf, only removing it with a long, steel shepherd’s crook.
The lathe had two blades diametrically on opposite sides locked in tool holders. Once locked on the pipe, we started cutting, removing a few tenths of a millimetre of metal on each rotation. While cutting, we tethered the airlift inside the cofferdam to allow it to continue sucking sand unassisted. A second airlift was also fabricated and sent down to assist, as the first one alone was insufficient to keep out the constant backflow of sand.
Once we had made the two cuts and removed the damaged cut-out piece, the two pipeline-end faces were ground smooth manually using a hydraulic grinder. Afterwards, we slid multiple colour-coded sections of the “Intelligent (Smart) Morgrip” flange assembly over the pipe ends as specified by the engineers and inserted twelve long, stainless steel bolts throughout the ring sections before bolting the end flanges together in a set sequence using a torque wrench.
No job is ever entirely smooth, though; a couple of mishaps occurred on this one, too. First, during a bell run changeout, the compressed air supply to one of the two operational airlifts was inadvertently shut off for an hour. The result was that the airlift got buried in the ever-flowing sand. It was impossible to recover and had to be abandoned, permanently lodged in the seabed. Mud or sand slides are a danger that can entrap a diver and are a concern that divers are mindful of when working in hollows and pits in the seabed.
Even with the small hiccoughs, when we finished, after lifting the cofferdam back onto the vessel’s deck, the operation took only four days. It saved Phillips Petroleum, the operator of the Ekofisk Field, a lot of money. If they had chosen to weld the damaged pipe, a dry welding habitat would have had to have been set up over the pipeline, costing at least fifty times more. With the job well done, all the teams back in the living chambers felt satisfied.
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The inherent dangers of dropping a load whilst lifting it are not the only hazards that can arise. Lift rigging on significant projects can weigh tens of tonnes. As the following three examples emphasise, crane blocks, wires and sheaves, winches, motors, breaks, welds, and bolts can all fail.
I first observed the consequences during the mid-eighties when on a Mobile Offshore Drilling Unit) MODU performing drilling operations in the Norwegian sector of the North Sea. A crane operator requested a young new roustabout to wash one of the main deck’s two crane pedestals. The young man was inexperienced and had not been provided with a work task description; neither was he given a task walk-through, nor was a risk assessment performed in those days. He eagerly attacked the task with a vengeance with drums of industrial detergent, soap, and a high-pressure industrial water jet.
Opening the pedestal hatch, he observed the boom wires, winch drums, and machinery therein were dirty and took it upon himself to clean there, too. The crane boom was raised at a forty-degree angle over the pipe deck and across the catwalk in the position the crane operator had parked and isolated it when he came down from his cab for a break.
Some hours later, proud of his effort, the dirty, soaking roustabout informed the crane operator that the crane pedestal was spotless. At this point, he was dispatched to another task in the mud shaker room. The crane operator proceeded to the crane, started the engine, released the hydraulically operated boom winch’s drum band brakes, and then all hell broke loose. With the entire winch room saturated in soap, the brake band pad friction was inadequate to stop the forty-metre-long lattice crane boom. It went into freefall, crashing down onto the pipe deck, deforming the catwalk, and its upper section broke and hung precariously by the lift cable down over the far side of the rig. It was a disaster, but blessedly, there were no fatalities. Drilling operations were halted, and the well was temporarily shut in and abandoned. The anchor spread was retrieved, and the rig was towed to the Coast Centre Base (CCB) for comprehensive investigation, repairs, and re-certification. The rig remained at CCB for an extended period, exceeding one month.
Two notable extreme cases of crane boom collapses have occurred where divers in bells at depth and in saturation chambers aboard the vessels were affected. Fortunately, such incidents seldom happen.
DLB Kuroshio One (K1) – 1979
In 1997, the HLV Kuroshio One (K1), a Derrick Lay Barge (DLB) built in 1972, was stationed at the Bongkot field, offshore Thailand, on hire to Total. She was a non-propelled flat steel bottom heavy lift barge measuring one hundred and forty-two metres in length and forty metres in width with a gross tonnage of fifteen thousand nine hundred and eighty-three. She had a two thousand-five hundred short-ton rated revolving crane.
The crane was stationary with its lattice jib (boom) in a forward position over the DLB Kuroshio One’s deck at a forty-five-degree raised angle. There was no load on the main hoist block, resting in a secured raised position. The DLB Kuroshio One was anchored on a northerly heading, and the sea condition featured two-metre swells heading east (beam seas). The water depth was eighty metres. The sat system had a single bell. Nine divers were in saturation, and they were running three-person bell runs.
The barge was hit broadside by a large wave set and rolled sufficiently to induce a side force that caused numerous coupling stud bolts on boom foot bearings to rupture and fail. One three-person dive team was in the bell. The ninety-six-metre-long crane jib weighing three hundred and fifty tonnes broke off from the spindle at the foot of the crane. The crane boom fell to the deck, missing the saturation chambers, with six men inside, but tearing the Hyperbaric Rescue Chamber (HRC) clear off its foundation. The HRC was not pressurised, and its doors were closed. The mangled lattice boom fell over the vessel side, taking the crushed HRC and other debris with it down to the seabed.
The diving bell, hanging at depth, was knocked sideways, tilted by the falling crane boom sections. The bell flooded with water. The bellman emptied the bell using the bell blowdown valve and then frantically pulled one of the two locked-out divers back inside the bell. When he tried to pull the second diver back, to his dismay, he only got the umbilical with the bailout bottle and mask still attached. The diver, an experienced Japanese national, had removed his dive gear and bailed, swimming to the surface. The boom landed next to him on the seabed, and he had been whipped by falling cables, causing heavy bruises on his back. He may have encountered the HRC under the mess of the crane boom and assumed it was the bell crushed under the entangled mess.
The HRC had a colour and size similar to the bell. Having been trained in the Persian Gulf, where divers ditched rather than sever their umbilicals, he ditched his equipment and free-swam up to the surface, whereupon he was assisted on board. Still alive, he was immediately ushered into a Deck Decompression Chamber (DDC) and pressurised on air back down to depth. He died soon after from severe pressure-related harm and injuries incurred during his initial rapid decompression.
The fatal accident’s fundamental cause was that the crane’s bolts were always assumed to be in compression, not tension. They had never been inspected, as this was excluded explicitly by the certification body. Several bolts had previously wholly failed due to corrosion. IMCA SF 03 98 (TC) reported that the finding stated there was no allowance for wave motion. It is believed that the incident could have been avoided by adhering to good maintenance, inspections, and working practices and adhering to the crane’s operating limits.
DLB Regina 250 – 2005
The eight-point moored HLV DLB Regina 250, owned by Valentine Maritime, Abu Dhabi, on hire to the Oil and Natural Gas Corporation (ONGC), was built in 1978/re-built in 1982, measuring ninety-six metres in length and twenty-six metres in width with a gross tonnage of five thousand three hundred and sixteen, capable of laying pipe up to sixty inches in diameter, with a crew capacity of two hundred and fifty persons. Consolidated Contractors Company (CCC), registered in the United Arab Emirates (UAE), owned and operated the dive system. On 01 April 2005, just three months before the Mumbai High North platform disaster, the heavy lift rigid pipe lay vessel was on location in the Bombay High field offshore India.
During a two-person bell run, the Regina’s 250 revolving two hundred and fifty-tonne capable, pedestal-mounted, main stern positioned crane’s lattice boom collapsed over the saturation system, damaging the dive control shack, the bell Launch and Recovery System (LARS) and the Hyperbaric Rescue Craft (HRC). The extent of the damage to the dive system was severe, with the crane boom draped over the HRC/sat system. The bell-handling launch and recovery system was rendered inoperable. The diving bell was at seventy-five metres depth.
The DSV Samudra Sevak, a vesselalso on hire to the ONGC of India on location in the same field, was requested to provide urgent assistance. The one hundred and one point eight meters long, nineteen point five metres wide, with a gross tonnage of five thousand four hundred and fifty-five tonnes Samudra Sevak was built in 1988 at Mazagon Dock in India with a single-bell eleven-man Comanex dive system.
The two Regina 250 bell divers stranded at depth were rescued by through-water transfer to the DSV Samundra Sevak bell, which was lowered to the same depth. Samudra Sevak was built in 1988 with an eleven-man Comanex dive system.
Sat dive sequence: DLB Regina 250 (Abridged Dive log) Number 86
17:35: Bell sealed.
17:45: Bell left surface.
17:50: Bell on the bottom and commenced diver lockout.
17:52: Crane collapsed on the dive system.
17:55: Lockout aborted/Bell sealed at seventy-five metres depth.
17:57: Divers reported all OK.
18:25: Main bell wire secured on the surface.
18:30: Standing by on Samundra Sevak for thorough water transfer.
19:39: Samundra Sevak on site.
20:13: After discussion between Supv/Supt of both vessels, decide to use Regina 250 bell umbilicals/helmets for transfer.
21:44: Samundra Sevak diver one established a swim line to Regina 250 bell.
21:55: Regina 250 diver one in the water.
22:02: Regina 250 diver one in Samundra Sevak bell.
22:14: Regina 250 diver one’s umbilical and hat returned to Regina 250 bell by Samundra Sevak diver one, ensuring the umbilical slack did not snag.
22:18: Regina 250 diver two in the water.
22:22: Regina 250 diver two in Samundra Sevak bell.
22:44: Samundra Sevak’s diver one secured Regina 250 diver two’s umbilical and hat externally onto Regina 250 bell.
22:45: Samudra Sevak diver one returned to Samudra Sevak bell/Personal transfer complete, bell containing four divers sealed/Bell recovered to surface.
It was reported that the Regina 250 went to Gujerat, India, for significant repairs to the dive system/bell handling equipment and crane before returning to work weeks later.
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The next day, the Seaway Pelican relocated the Ekofisk 2/4 A (Alfa), the first jacket installed at the vast Ekofisk field in 1974. Our task was to connect three sections of an eight-inch, heavy-wall water injection spool by bolted flanges. The task involved connecting the three spool sections between a pre-installed riser flange just above the seabed at one of the platform legs and an end flange on a pre-existing eight-inch water injection pipeline nearby. We, divers, call that work “tie-ins”, which are typical offshore divers tasks as tie-ins work cannot be performed by remotely controlled vehicles (ROVs). The pipeline is pre-laid on the seabed running up to about a hundred metres from the platform, where divers connect it to the spools via bolted end flanges. First, the prefabricated spools are overboarded and landed close to their final position, then floated and pulled into position. Divers then thoroughly clean the pipe flange gasket groove, put in some bolts, position the gasket, and insert the remaining flange bolts. It is complicated work, as the flanges must align perfectly in all cardinal positions. The bolt nuts are then hand-flogged sequentially before using hydraulically operated hydra-tight equipment. The hydra-tight system has multiple bolt jacks that screw onto the extruding bolts. Then pressure is added, uniformly pressing the flanges together and stretching the bolts. The bolt nuts’ final turns are done by hand using a dowel pin before the pressure is released from the hydra-tight pump, snapping the bolts tight.
When assembled, the spool would be shaped like a letter Z and measure over eighty metres as the crow flies between the pipeline and riser flanges. Its length measured along the Z shape was close to a hundred and twenty metres.
Gary (Sharky) Ward and his dive partner, nicknamed Dave Cutts, tied in three of the four flanged connections during their eight-hour bell run. They started at the inner riser flange, welded to the riser. The lower end of the pre-existing vertical riser curved out from a platform leg and ended one and a half metres above the seabed. Ten individual two-tonne capacity airbags were installed and filled to make the spool sections naturally buoyant and enable the three spool sections to be sequentially and systematically floated into position. The airbags would also aid the line-up, adjusting the spool sections in the horizontal and vertical planes. The correct line-up was critical to enabling the bolted hydra-tight connections to be completed within the given tolerances of a few millimetres.
Towards the end of the dive, they were striving to line up the fourth and final flange to the pipeline flange. The diving bell had been positioned halfway between the riser and pipeline flanges to enable the divers to reach both the riser and pipeline flanges. Gary was in the middle of the centre spool section, and Cutts was at the outboard pipeline end. Two bell partners and I were on the surface in the second bell, preparing our bell to be lowered to depth to change out at depth and continue with the spool’s final tie-in work.
Suddenly, Cutts shouted that Gary had to stop filling the airbags as the spool was buoyant and floating at the outer end. Gary replied that he was not filling any air and immediately grabbed hold of the closest airbag dump (vent) line and pulled it for dear life. Cutts scrambled clear as the spool continued to rise. Garry kept dumping air, straddling the spool until he was above the top of the bell eight metres off the seabed. He then self-perseveringly jumped clear, having reached his maximum upward excursion limit.
Given their limited upward excursion limit, Gary and Cutts then vented off the few airbags they could safely reach. At this stage, they returned to the bell, were recovered to the surface, and locked onto the system aboard the Seaway Pelican.
The outer end of the spool had floated up to the surface, bending the spool into the form of a long, squiggled banana. It became apparent that the one hundred horsepower three-ton mass work class ROV had inadvertently snagged its tether around one of the outer airbags. It lifted the negatively buoyant spool from the seabed after flying upwards and activating the Tether Management System (TMS) to spool in the ROV tether. This enabled the air in the airbags to expand, increasing the buoyancy until it reached the point of no return, and the spool’s upward journey could not be stopped.
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On 30 August 2008, a similar dangerous occurrence occurred during saturation diving operations offshore Malaysia at the Bunga Orkid D Platform, Northern Field. The operation was to relocate into position a twelve-inch spool measuring eighteen metres in length, with a weight in air of thirteen point seven tonnes on the north side of the platform. The spool was to be flanged bolted between the platform riser and a seabed pipeline.
The spool was on the seabed, the bell at the working depth six metres above the seabed, two divers were locked out of the bell, and the bellman was inside the bell. Four lift bags were pre-positioned and secured to the spool at dedicated engineered lifting attachment positions. The two-tonne capacity lift bag at the gooseneck riser end was fully inflated first. Diver one was changing out the deflated second two-tonne lift bag. The third five-tonne lift bag was inflated with air to approximately half its capacity; the fourth and last lift bag closest to the pipeline end flange was in the process of being inflated by diver two, who had been given clear, specific instructions to inflate this lift bag to no more than three-tonnes, about half its capacity.
After filling the airbag to provide two to two and a half tonnes of lift, with approximately a combined eight tonnes of lift, diver two noticed a slight movement of the spool piece; he immediately stopped inflating and started pulling the airbags dump line. This reaction, however, did not prevent the spool from lifting and leaving the seabed, gaining speed as the air in the bags expanded. Diver two’s umbilical was snagged by rigging on the spool, and he ascended with the spool uncontrolled. His umbilical communication and video cable parted during this ascent, and he experienced restricted gas flow to his helmet. He was lifted from the seabed at fifty-five upward to thirty-six metres before he could untangle, free himself, and drop back down to the seabed.
Diver one located diver two’s umbilical and got to diver two after he had disengaged from the spool. Diver one accompanied diver two back to the diving bell, after which diver two locked back into the bell, followed by diver one. The bellman reported all was OK, the bell hatch was sealed, and the dive was aborted.
The ROV was deployed to ensure no damage or entanglement had occurred during the spool’s uncontrolled ascent. The diving bell was then recovered to the surface and locked onto the system.
In this instance, at the time of the incident, no holdbacks were in place to secure the lift bags to Dead Man Anchors (DMAs) on the seabed that would have inverted the bags. No holdbacks were in place between the spool and seabed DMAs that would have prevented the spool from being taken to the surface. Routine established procedures had not been complied with.
On 04 May 2009, a similar accident involving airbags was fatal. Christopher (Chris) Tate Wilson, aged thirty-eight, an American national, ex-United States Marine Corps who had been a commercial diver for thirteen years, was under contract with the energy company Veolia ES Marine Services. He was in saturation on the DSV Kingfisher (ex-Seaway Kingfisher, ex-Atlantic Surveyor, ex-Yuri Trifonov), a DP Class II vessel with accommodation for sixty persons plus twelve in saturation.
The Kingfisher was built in Gdynia, Poland, in 1989. She measured eighty-nine point ninety-eight metres in length and seventeen point thirty-nine metres in width with a gross tonnage of three thousand six hundred and seventy-two. The vessel had a twelve-person saturation system rated to two hundred metres, with a single-side launched three-person bell, a twelve-person Hyperbaric Rescue Chamber (HRC), and a Triton XL-25 work class ROV. The vessel was on-site on DP in the Vermillion area, ten miles south of Sabine Pass, off Galveston, Texas, Gulf of Mexico.
During a bell run, while locked out of the bell on the seabed at sixty-three metres, Christopher was performing a partial pipeline decommissioning operation (Segment no. 3397), floating a pipeline section of the Stingray pipeline when the airbag anchoring mechanism failed. The airbag was oversized, there was no holdback line, and tragically, the airbag inverter line was secured to an inadequate-sized weight. The airbag rigging failed. Christopher was entangled in the rigging and dragged upward from the seabed forty-three metres to a depth of twenty-three or twenty-two meters, suffering an uncontrolled rapid decompression. He could not free himself. His bar-tight umbilical and the weight of the diving bell then stopped further accent. It is stipulated the bell trunking was seven meters off the seabed, and he had thirty-three meters of umbilical out of the bell.
The situation would have been dire with few possibilities of rescue.
- The bell could not be raised as that would cause Christopher further Decompression Sickness (DCS) and exacerbate existing barotrauma.
- The divers in the bell could not climb up to help as their maximum upward excursion was only a few meters.
- The vessel was a single bell system.
Air divers could have dived if a diving basket and winch had been ready. The dive supervisor could have lowered the diving bell as deep as possible to increase the depth/pressure and slightly reduce the lift.
The Triton XL-25 work class ROV was probably their only viable option for the attempted rescue. As Christopher had not managed to disentangle himself when he was finally reached and brought back down to depth, tragically, all attempts to resuscitate him were futile.
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Aboard the Seaway Pelican, the working class ROV untangled itself, was recovered to the deck and fitted with two sharply pointed “Mora-Norwegian Fisherman” knives on its Five-Function arm (5F). Upon being relaunched, the ROV stabbed the airbags, deflating them and enabling the spool to sink towards the seabed. The spool landed back on the seabed in nearly the exact position it had been before it took off.
After a two-hour standby period in the Transfer Under Pressure (TUP) chamber, our bell team received the long-awaited clearance to launch from the offshore manager. The delay had been due to the working-class ROV engaging in spearfishing balloons. Upon locking out from the bell and reaching the work site to perform an inspection, we found that the spool section closest to the riser flange was seemingly unaffected. However, the short horizontal riser section protruding from the clamp welded to the jacket leg had understandably been bent/deformed after being at the pointed end of a tensioned hundred-and-twenty-metre-long crowbar.
The Phillip Petroleum client requested that the spool be unbolted, a new gasket ring inserted into the groves, and then hydra-tightened. One can only summarise that he was not overtly concerned as the pipeline was for water injection, not hydrocarbon production. I thought this might cause more harm than good, but it was neither my prerogative nor station to voice concern. Having worked with pipe and flanges at the CCB base for years and having a mechanical schooling background, I attacked the task with a vengeance; a gruelling, intense seven hours ensued.
First, the unbolting had to occur, which was solved relatively easily by increasing the hydraulic pressure on the hydra-tight jacks. (These hydraulically powered jacks work by pulling/stretching the bolts, then the bolt nuts are turned by hand through a cut-out window in the jacks aided by a podger inserted through a cut out in the body of the jack into small, recessed holes on the flat sides of the nuts.)
Second, the flange grooves were inspected, and a new gasket was inserted. Diver two kept himself busy shifting out the punctured airbags with replacements, adding numerous three-ton capacity come-along chain pulls, and repositioning installation aids for the fourth outboard tie-in. He also assisted me by adding new airbags at the spool end close to the deformed riser elbow to aid the reconnection.
Third, the tricky part started. The two flanges at the deformed end would, of course, not line up. The gap at the six o’clock position was fifteen to twenty millimetres wider than the gap at the top dead centre (12:00 O’clock) position. I requested several eight-millimetre thick, slightly angled steel shims to be fabricated aboard the ship in the welding workshop and sent down by the crane. These were duly inserted and duct taped between the flanges at the (10:00-14:00 O’clock) positions. Six flange bolts were inserted through the lower six flange bolt holes, a challenging task. Hydra-tight jacks were then installed on the lower six bolts (three outboard jacks and three inboard jacks).
I then asked for absolute maximum pressure and more to be given by the team on deck controlling the high-pressure pump, providing and maintaining hundreds of bars of hydraulic pressure via the small diameter hotline that came down from the surface. The immense hydraulic force squeezed and closed the lower gap to eight millimetres. The lower set of six bolt nuts were swiftly secured, effectively locking the tensioned flanges into place. Subsequently, the upper-positioned spacer shims were individually removed, aided by the most oversized sledgehammer the riggers could locate on board the vessel. The top set of six bolts and nuts were then hand-tightened. Due to exceeding their elasticity limit during the over-pressurisation, the lower six over-tensioned bolts were individually replaced. To conclude, a comprehensive hydra-tight operation was carried out following the established procedure.
At this stage, my hat camera, which had been intermittent since the start of the dive, miraculously started working perfectly again. The work site was tidied, and the bell run ended, arriving back on the system eight hours after locking off. The offshore manager, Alan Sealey, called into the system and thanked me for my effort.
This incident and several other airbag-related incidents reinforced the need to be extra vigilant when working with airbags. The pipeline was pressure tested two weeks later and passed with flying colours.
Before we could start decompressing, there was more work to be done. The seabed surrounding the North Sea’s older platforms was often a scrap trader’s backyard. Most of the scrap was accidentally discarded metal elements, either from scaffolding or other metal objects, but sometimes intentionally dropped from the platform or the ships serving it. If metals are not removed, they impair the efficiency of the anodes placed on and around the platform’s steel jacket and submerged structures to protect against corrosion. In addition, the scrap can cause difficulties and dangers for diving and ROV operations. So, after completing the spool tie-ins, the teams repeatedly returned to the seabed through the following days to gather metal debris.
The Seaway Pelican’s crane lowered large half-height baskets for us to fill with the discarded metal. The term basket may be misleading, though, because, in reality, they are either twenty-foot long and eight-foot-wide or ten-foot by ten-foot square containers with sheet plate walls and heavy grating bases. Half-height refers to the container walls being four feet tall, half the height of a standard twenty-foot shipping container.
If items were too heavy for the divers or deeply buried in the seabed, we would ask for assistance from the working-class ROV. The physical strength of a one hundred horsepower work class ROV was impressive, and in the early nineties, divers could work alongside the ROVs. Today, a safety zone is stringently maintained. The ROV could grab on with its five-function arm (5F) and rip the embedded heavy scrap out from the seabed like a child pulling a spoon from a muesli bowl.
When we had finished tidying up the chosen seabed area, we were dispatched to install clamps and control pods. These subsea electrical and hydraulic-controlled pods are remotely operated units electrically connected to platforms. When they were in place and connected, the working saturation was over for our team and one of the other three teams. Two three-person teams started decompression in the six-person decompression chamber, blown down with the six men who replaced us. During our decompression, the vessel transited south to Immingham, a large industrial area by the Humber River estuary on the east coast of England, to load out equipment for the next project.
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In addition to the pigging operation, we were to connect the same flanged pipeline end via seabed spools to the dedicated riser leading up to the Frigg platform.
Connecting the spools on the seabed at a one hundred and twelve metres depth took the dive teams three days of hard labour, but we still had one more job to do before we could start decompression. This time, we had to fix somebody else’s mistake and here is where the big excavator came into the picture.
During offshore oil drilling, the opening hole is usually made with a thirty-six-inch, multi-headed drill bit called a hole opener. This enormous hole can reach as deep as fifty to sixty metres below the seabed. The rig’s drilling crew also used this procedure in this case. The drilling crew inserted a thirty-inch thick-walled conductor pipe string into the hole protruding a few metres above the seabed. The technical name for the upper section of the conductor pipe is the wellhead hanger conductor assembly.
Before they continued drilling, the drillers landed a massive open-top wellhead protective structure over this particular drill hole. They next used a twenty-six-inch drill bit to bore down hundreds of metres to a predetermined depth. Then they ran a twenty-inch casing string down through the wellhead and hung it off inside the slightly larger wellhead hanger. The blowout preventer was connected to the wellhead to recover the drilling mud and prevent potential blowouts.
The next stage was to drill an even narrower hole and insert more casing pipe. Cement would be filled in the annulus between the Thirty-inch conductor, twenty-inch casing and the thirteen and three-eighths-inch casing, followed by strings of tubing down towards the oil or gas reservoir. All this is everyday work for professional drillers on drilling rigs. So far, so good.
Concrete is pumped down at intervals during the drilling program into the encasement voids via kill and choke lines to strengthen, stabilise and plug the voids between the different-sized pipe strings that make up the borehole. The cement is pumped down through kill and choke tubes clamped onto the inter-connected riser sections, running from the top of the seabed blowout preventer up to the spider deck telescope joint positioned under the Mobile Offshore Drilling Unit’s (MODU) drill floor.
Here is where it went wrong for the drilling rig’s cementing team. They initiated the concrete filling process, but due to a leak or an incorrect valve setting at the top of the wellhead encasement, hundreds of cubic metres of concrete poured out of the subsea BOP valve assembly onto the seabed instead of down into the annulus of the borehole where it was supposed to go, completely engulfing the wellhead protective structure. The heap of hardened concrete looked like a bronze-age burial mound the size of a building. It had to be removed before the hook-up work to the wellhead started, as it had utterly buried the subsea protective cover. Initially, it had seemed like an almost impossible task, but sitting in the Pelican’s pressurised living chambers after being briefed, the divers discussed how brilliantly straightforward the solution was.
The problem had been presented to engineers in Haugesund some weeks earlier. After much discussion, one of the engineers came up with an idea. They would use an excavator. First, all his colleagues laughed and told him that it was impossible. How could you put a land-based digger on the seabed? They soon stopped making fun of him because he was intelligent and had already thought of explanations to counter their arguments.
The work to convert the digger for subsea use started right away. First, the motor and hydraulic volume tank were disconnected, lifted, and set on the deck. Then, one-hundred-and-ninety-metres of hydraulic pressure, return, and case drain hoses of larger than standard dimensions were connected between the deck-placed motor and the excavator. These hydraulic lines were long enough to reach the seabed with plenty of extra left to ensure the ship’s offset and movement by the sea swell would not tension and snap them. The vessel’s main crane lifted the heavy excavator when everything was attached and tested on deck. It was over-boarded and slowly lowered one-hundred-and-twelve metres, observed by the vessel’s ROV, until it landed on the seabed below. The excess hose was attached to a buoy using a holdback wire, resulting in a bundled loop floating like a gooseneck thirty metres above the digger. Deck winches were connected to assist with the heavy hose deployment and recovery.
Once the excavator was in place next to the concrete dome, the bell with the first team of divers arrived. Except for two Norwegian divers named Geir K Knag and Trond Kleivane, none of the twelve saturated dive team members had prior practical experience using such a large excavator. Therefore, we had to have additional hands-on job training while at depth learning how to operate the different controls correctly. It was probably a hilarious sight for the dive supervisor and others on the Seaway Pelican watching on their monitors as the divers climbed into the digger’s control cab in their bulky suits and helmets with their long umbilicals trailing behind them. After some trial and error, we figured out how it worked and started attacking the dome.
The standard front-end grab on the excavator soon proved insufficient power to break the most solid sections of the concrete mass, so the deck crew added a large, pointed tooth to the grab to smash the concrete. We had to perform the work carefully to avoid damaging the wellhead or hitting the other diver standing in front, providing verbal instructions. Once we had worked for a couple of days, leaving a sufficient pile of concrete bits lying around the worksite, the regular grab was reinstated to lift the debris into a mesh basket that the crane lifted away and dumped on the seabed at a safe distance.
We divers enjoyed ourselves immensely while playing with our new subsea toy, but driving the vehicle on the seabed was not all fun and games. On top of pieces of concrete, clouds of cement particles chiselled off the dome spread through the water, the wheel drives disturbed the sandy seabed, and we often lost all visibility.
On one occasion, when my shift’s bull run was over, the next team arrived to take over in the murky darkness. Two of the men on the team were from Liverpool, Mick and Mack. Mick was the designated bellman, while Mack and another diver had the pleasure of playing with the excavator. During Mack’s attempt while working in almost zero visibility, Mack raised and swung the grab around, slamming it into the bell. One of the grab’s teeth got stuck on the outside of the bell in between the bell’s external reserve gas bottles and pipework, and while trying to get it loose, Mack ended up shaking the bell violently with Mick screaming through the clear comms for him to stop. Thankfully, the weather was calm, so the bell was not heaving excessively. This incident was not funny at the time, as it could have seriously damaged the bell and ended in tragedy.
Mack’s wild excavator driving caused banter later on. Someone also took the time to sketch some humoristic drawings showing Mick’s terrified face (reminiscent of the painting Skrik (Scream) by Edvard Munch) peering out the bell’s porthole with the excavator’s bucket snagged on the side of the bell.
Overall, though, the job was executed beyond what we had dreamt possible. The wise engineer was applauded and received well-deserved accolades for his Donald Duck ingenuity. Close to a decade later, I once again had the pleasure of working with this engineer on an extensive diver-less project at depths down to three hundred metres using rigs, vessels and ROVs to elevate/lock on place the one hundred and sixty-ton Vigdis and Tordis template manifolds at the Snorre field.
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Harald Klinge displayed his unique gallows humour when he told a story about a foul odour in the chambers during the horrible task of retrieving bodies after the MODU Alexander L. Kielland disaster. While on a lockout on the seabed, he found plastic bags with urinal tablets that neutralise the odour from human urine. He brought these urinal tablets back to the TUP (wet pot) as the smell in the TUP was atrocious when the urinal head and toilet were used. Harald, while laughing, says that the stench was unbearable after Ivar had used the toilette. He threw some white urinal pellets into the pot, not overtly contemplating the potential consequences.
Over time, these tablets emitted a dense invisible gas that remained concentrated in the chambers and saturated their bodies. Upon arriving home after decompressing on 20 April 1980, Geir Ivar’s wife would not share any intimacy with him as she said his body smelt so bad. On Monday, 21 April 1980, Yngve Tveit, Geir Ivar Jorgensen, Harald Klinge and Einar Andersen attended an advanced first aid course at Rogaland Sykehus. The other students complained about the horrible smell their bodies emitted. Harald also mentions that Geir Ivar temporarily fainted during the course due to exhaustion and dehydration. The nurse asked Harald to insert an IV needle into Geir Ivar’s arm. This Geir Ivar disapproved of and was adamant that the nurse should perform the procedure, not Harald, under any circumstance, to much laughter and banter by the other course participants.
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However stringently and vigilantly performed, safety orientated, and careful every participant is, unfortunately, events still occur. On the night of 05 June 1997, while bell diving from Seaway Pelican, two of my regular dive colleagues, Paul Cruickshank and Steve (Stephen) Broom, along with Graham Edmonds, experienced a contaminated bell atmosphere incident while at depth in the British sector of the North Sea.
The Central Area Transmission System (CATS) subsea gathering station manifold has a fourteen-inch diameter condensate export riser connected to the Everest Liquid System (ELS) subsea pipeline that merges into the Forties Pipeline System (FPS). The CATS pipeline transports methane, ethane, propane, butane, natural gas liquids, and various contaminants (such as water, hydrogen sulphide, and mercury) from offshore production facilities on the CATS systems offshore Riser Platform (CRP) to the onshore terminal for gas treatment, metering, and processing.
Steve, a former Royal Marine who served from 1981-1986, trained as a commercial diver after leaving the service. He worked on inshore projects for the first five years of his diving career (1987-1992) before working offshore from 1992 onwards. He started saturation diving in 1993, was certified to become a dive supervisor in 2009, and stepped into the supervisor role in 2013 after twenty years of North Sea saturation diving.
Steve & Paul were both experienced saturation divers and had received their diver training at Plymouth, England. During that night’s bell run, they were tasked to remove a blind flange from a seabed pipeline at one-hundred and twenty-five metres of water depth. The bellman on this dive was Graham Edmonds. It was Graham’s first and last time on a saturation diving project. In the aftermath of that saturation, Graham, who did not have a military background, suffered quite severely from mental trauma and undertook a lawsuit against his employer.
Both divers were wearing oversuits to protect their diving suits from contaminants. These oversuits were constructed from thin waxed cotton material. Unfortunately, they absorbed lighter volatile fluids, such as condensate, but they worked well to prevent grease and mud from contaminating the hot water suits.
This type of diving operation was a regular occurrence. Engineers, divers or supervisors didn’t deem it excessively dangerous, provided the pipeline was at ambient pressure and no hazardous hydrocarbons were lurking behind the sealed flanges. The section of the pigging loop to be broken into was supposed to have been pigged with a slug of gel to remove unwanted chemicals and hydrocarbons before unbolting and splitting open the flanges. Regrettably, this was not the case; the fluid inside the pipeline contained toxic, volatile condensate compounds.
The dive supervisor on this occasion was American Bob (Robert) Davis, a very calm, experienced and professional dive supervisor who had made Scotland his new homeland. In the early seventies, Bob started his career as a diver for Taylor Diving and Salvage, then started working for Stolt Nielsen Seaway.
Here is the event sequence in Steve’s words: “We locked off the dive system at approximately 19.00 and were at depth, on the worksite, at approximately 19:35. Paul was diver one, and I was diver two that day. While removing a blind flange from a fourteen-inch diameter pipeline, we noticed something other than ‘gel’ flowing out from the broken flange seal. It turned out to be condensate. We had suspicions because we could see a shimmer as the liquid escaped and rose through the water column. We could also smell it, even though the water and our helmets suggested it was of a very high concentration. This concern was mentioned to Bob, as we were expecting there to be a gel plug behind the flange. At around 22:00, towards the end of the dive, the Seaway Pelican’s other diving bell arrived at depth with the following shift team to take over and continue the work. Fortunately, this was a bottom handover, as the divers from the other bell had to come to our assistance.
“I was the first diver back to the bell. We were usually pretty slick at getting ourselves back to the bell at the end of a dive, so it didn’t take very long. After returning inside and removing my diving helmet, I immediately noticed the overpowering smell of hydrocarbons. It was the vapour from the condensate evaporating from my over-suit, hot water suit, umbilical and other equipment that had been in contact with the volatile fluid. I had to make a quick decision before being overcome. I opened up the diver-operated bell blowdown valve in an attempt to flush the bell with clean gas while preparing to get Paul back into the bell. I believe the flushing was not futile. It definitively helped buy us some time.
“By this time, Paul was on the bell stage, ready to enter the bell. At this stage, Paul, who thankfully still had his Superlite hat and bailout on, was unaffected by the gas fumes. From this point forward, I have no further recollections, as Graham and I were more or less semi-unconscious and incapacitated. Paul, with superhuman effort, was able to assist in closing the bell’s inner bottom door. He then proceeded to help both Graham & me with the Built-In Breathing System (BIBS – a secondary breathing system within the bell). Having swam over from the second bell, the two other divers assisted from the outside to get a seal on our bell’s bottom door.
“Paul managed during the recovery to flush the bell and communicate with Bob topside in dive control while constantly still wearing his full diving gear, bailout, and hat. The bell was then recovered to the surface and locked onto the TUP trunking.
“I don’t recall much until I came around in the transfer lock with all my diving equipment and suit removed (bagged up and sent out). It was all hazy for me from this point onwards. I was naked, apart from a towel, with my head in the lap of Kenny Ebrell, another diver, who was administering a high Partial Pressure Oxygen (PPo2) gas mix through the chamber’s BIBS system.
“It was a Godsend that we were in a ‘side-locking’ dive bell instead of a ‘bottom-locking’ bell. With a side locking bell, operators outside of the bell could override the side door. Rescuers could then get in and get people out. It would be challenging to open the door with a bottom locking bell, especially in a worst-case scenario if three unconscious divers were lying on top of the bottom door.
“I’ve no idea how long I was semi-unconscious. I eventually came round. I got a few funny looks from the guys. I don’t think that they were expecting that outcome! We were given the option to decompress after the incident but chose to stay in saturation and carry on working, get back up on the horse, so to speak. In hindsight, I don’t think it was the right decision. It did affect me, but being young and ex-military, I didn’t want to admit it at the time. I’ll never forget the day that Paul and the rest of the team saved my bacon (apart from the bits that I just can’t recall). I will be forever in their debt.”
Upon the bell being locked back onto the TUP trunking, the life support supervisor was duly and understandably concerned that the toxic bell atmosphere would enter the whole saturation chamber system. So, he over-pressurised the transfer lock while venting back the diving bell, creating a gas flow from the transfer lock towards the bell. Yet another problematic issue arose after the bell was locked onto the TUP trunking. It occurred because the BIB’s supply lines in the transfer lock were not long enough to reach through the bell trunking into the bell. Standing by in the transfer lock, the rescue team would need these to access the bell and retrieve the two incapacitated men.
Bob (Robert) Davis, who was on the panel in dive control at the time, experienced one of the most demanding, nerve-racking days of his long career in the diving industry.
The Stolt Comex Seaway (SCS) internal incident report number 41/97 (ABC), along with the International Marine Contractors Association (IMCA) – Safety Flash – Bell contamination by condensate flashing off – 02/1997 was shared far and wide to all diving contractors.
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There have been eighty-two registered North Sea divers’ deaths between 11 June 1966 and 27 January 2016. Ten of these men succumbed to gas-related issues, either while in the water, the bell, or inside saturation chambers. One other is still an obscure unresolved mystery with several speculated causations. These gas atmosphere calamities occurred between 11 April 1974 and 21 February 1984. It was a tragic decade of death, but since that last fatal February day in 1984, no diver gas-related deaths have occurred in the North Sea (this statistic of gas-related deaths does not include gas-related deadly subsea explosions.)
These are the eleven deceased men. May they be remembered with the respect they deserve.
11 April 1974
Marc G. G. Barthelemy
Marc died during a saturation dive in the British sector while working for Comex. He was only twenty-four years old. The official report claimed he drowned in the bell trunking due to exhaustion, but there is evidence that French-born Marc lost his gas supply, and when he returned to the bell, the Swedish bellman pulled his umbilical, dragging him away from the bell. In the panic that arose, several of the involved crews reverted to their native languages, adding to the ensuing chaos. The bellman then cut Marc’s umbilical, closed the hatch and told dive control to recover the bell. Upon arriving at the surface, Marc’s body was found draped over the bell weights. Precisely, what happened is still a mystery, but one of the main theories is that both Marc and the bellman were subjected to incorrect gases, perhaps causing one to go crazy and the other to die.
27 August 1974
Peter Kelly
Peter Kelly, a twenty-seven-year-old British national, died during a bell bounce dive to eighty-one metres while diving from the Dutch vessel HLV Champion at the Ekofisk Field on the Norwegian sector for Northern Divers Ltd (Hull). The client was PPCOM. Both divers in the bell were wearing breathing masks, breathing a diving mix of helium & oxygen as the bell atmosphere was air. They got a slug of pure helium via the umbilicals to their diving masks on the descent. Peter, wearing a full face mask, collapsed and died. Bell partner Danny Stokes survived; he was wearing a half mask that blessedly dislodged. The gas quad was not tested before being connected to the bell’s supply.
15 October 1974
Gary Shields
Twenty-one-year-old Briton Gary Shields was diving for Comex from the DSV Coupler 1 Oregis at Ekofisk in the Norwegian sector. The saturation dive was at a depth of seventy-two metres to work on the Ekofisk pipeline. When Gary had finished his work and returned to the bell, the gas supplying his umbilical was closed. (The dive control gas panel was missing a non-return valve on the supply gas. When the surface changed the diver’s gas quad, the diver would return to the bell while valves were closed.) At that time, the superintendent entered dive control, asking the diver how he had secured the sling on a piece of pipe to be retrieved. After a brief discussion, the diver was asked to add a second turn of sling around the pipe. Gary took this as an order, put his mask on and locked out. It is disputed if “diver leaving bell” was announced by his colleague, the bellman.
With only the remaining gas in his umbilical to breathe as the surface supply was closed, he soon ran out and did not switch to his bailout bottle. It is unknown why. He became short of gas and attempted to return to the bell. In so doing, his umbilical turned around the sling wire to the surface. He tried to cut his umbilical, still without communicating with dive-control. He ran out of gas, trying to cut his umbilical and then screamed. The scream made the men in dive control realise the diver had locked out. The gas supply from the second gas quad was immediately opened, but there was no response from the diver. The bellman immediately locked out, but upon reaching him, he found Gary lying on the seabed without his mask. His umbilical was partially severed, and the knife was lying beside his body on the seabed. Lost gas, entangled, did not use bailout, attempted to cut umbilical, and asphyxia was the official cause of his death.
14 June 1975
George W. Turner
Planning to conduct a visual survey at a maximum depth of fifty metres, George entered the water in scuba equipment from the pipelaying barge Choctaw. He worked for Comex in the Norwegian sector. The seabed depth turned out to be sixty-nine metres, and when George let go of his lifeline, two divers entered the water to help him. They quickly returned violently ill and vomiting. The standby diver went in but also ran into problems and developed narcosis. Although confused, he still managed to locate George’s body on the seabed. All divers had bottles filled with the same compressor. The “official” report stated that George had suffered food poisoning (the only person on board to do so).
09 September 1975
Peter Holmes and Roger Baldwin
In the accident mentioned earlier in detail, Peter Henry Michael Holmes, aged twenty-four and Roger Baldwin, aged twenty-nine, died on board the semi-submersible Waage II drilling rig. Both men died from hyperthermia in the chamber due to the extreme heat generated by rapid gas compression.
12 January 1976
John “Scouse” Howell
John died at only twenty-seven years old during a dive to one hundred and forty-six metres from the Western Pacesetter 1 drilling rig in the British sector. He was still in the Navy but working part-time for prospective employers before ending his duty. The job was for the company Subsea, and their official report suspected the accident happened because John either switched off his gas supply or knocked the ball valve. Other sources indicate that he passed out after leaving the bell, suggesting contaminated gas. The bellman was unable to get him back into the bell and chose to tie him to the outside. Then, for an unknown reason, he removed John’s helmet. The autopsy stated that the cause of death was drowning.
10 May 1977
Craig Michael Hoffman
On 10 May 1977, a tragic unresolved incident unfolded on the MODU Venture One drilling rig onsite in the British sector of the East Shetland Basin, North Sea. American diver Craig Hoffman, aged 22, lost his life while performing a bell bounce dive for inspection duties. The mission was three nautical miles east of the North Cormorant oil field and at an approximate depth of about one hundred and fifty-two metres. The operation involved lowering a blowout preventer (BOP) to the seabed at a depth of one hundred and sixty metres.
Richard Pettit, a diving supervisor from International Underwater Contractors (IUC), was instructed to oversee an inspection of the wellhead guide base to confirm it was free of any hindrances to the BOP’s installation. Divers Dave Hammond, aged 29, from Dundee, Scotland, and Craig Hoffman from Delaware, United States, were assigned to conduct the inspection. Both men were experienced professional oil field divers.
After halting the bell’s descent at a depth of one hundred and fifty-two metres, Pettit had the divers scrutinise the guide base from the bell’s portholes for about ninety minutes. Contrary to expectations, the divers discovered wire ropes hanging from three of the four mini-guideposts, requiring their removal or adjustment. Hoffman exited the bell, clad in a hot-water suit, and Hammond stayed behind as bellman in a dry suit. Upon reaching the guide base, Hoffman realised that cutting away the wires was the only option. Richard Pettit, monitoring Hoffman’s breathing rate, advised him to pause frequently.
One hour later, Hoffmann had hacksawed over two of the three guidewires. Pettit then opted to recall Hoffman to the bell and send Hammond out to cut the third remaining wire. Once back in the diving bell, Hammond switched places with Hoffman, who dressed in the same diving equipment that Hoffman had been using. Hammond later testified that the gear exchange proceeded without any anomalies. Approximately twenty minutes afterwards, Hammond left the bell in high spirits and promptly reached the work site to tackle the final wire.
Meanwhile, back inside the bell, Hoffman stayed in contact with supervisor Pettit via headset. Hoffman relayed details about the bell’s oxygen levels and requested that Pettit have Hammond double-check some of his previous work. Pettit later stated that Hoffman’s communications were entirely coherent.
While Hammond was in the midst of cutting the final wire on the guidepost, Pettit was jolted by a bizarre, high-pitched electrical sound in his headset. He quickly called the bell to check Hoffman’s well-being but got no reply. Hammond, who was almost finished severing the third wire, indicated he had “one strand of wire left to cut through.” Nevertheless, Pettit emphatically commanded him to abandon his task and return to the bell immediately. Dropping his tools, Hammond commenced hauling himself towards the bell.
When he was approximately two metres away, he discovered Hoffman floating in a lifeless posture within the bell’s trunking, his limbs hanging down in the water. Initially, Hammond attempted to push his unresponsive colleague into the bell but found it impossible. Instead, he manoeuvred Hoffman out from the trunking and clambered through it into the bell, ensuring that Hoffman neither drifted away nor sank to the ocean floor. Once inside, he partially pulled Hoffman’s body into the bell, arranged his arms across his knees, and initiated mouth-to-mouth resuscitation.
Shortly after, the communication link between the surface and the bell mysteriously faltered. Over a year later, during court proceedings, Pettit testified that communications had begun to degrade after Hammond re-entered the bell and began tending to Hoffman. He stated, “It had completely disappeared at one point, compelling me to leave and seek external assistance.” Pettit rang his corporate headquarters, detailing the precarious situation to General Manager Stanley Kellogg—that he had lost communication with the bell and couldn’t bring it to the surface with the doors ajar. Kellogg provided counsel and then notified the Department of Energy. He also reached out to Offshore Medical Support and contacted both Comex and Vickers to request vessels capable of conducting dive rescues.
Aboard Venture One, Pettit managed to re-establish contact with the diving bell as Hammond persisted in his attempts to resuscitate Hoffman. After approximately twenty to twenty-five minutes, Hoffman showed no signs of life, and his pupils failed to react to light. Pettit instructed Hammond to bring Hoffman’s body fully into the bell, but Hammond was unable to comply.
When questioned during the formal inquiry, Hammond explained, “He was nearly as heavy as I am, and he was wearing a sodden hot-water suit, a hefty piece of kit that added to his weight. It was a completely unresponsive weight, no assistance whatsoever, and given the confined space I had to operate in, I couldn’t manage to get him fully into the bell.”
In a complicated and emotionally charged situation, Hammond confirmed Hoffman’s death to Pettit. By then, Hoffman had been unresponsive and without breath for an hour. Given the precariousness of the communications link with the diving bell, Pettit made the pragmatic yet heartrending decision to have Hammond secure Hoffman’s body to the exterior of the bell, close the interior door, and prepare the bell for its ascent to the surface.
Once the bell had returned topside, an air diver was deployed to retrieve Hoffman’s body and place it in a recovery basket. The bell was hoisted onto the vessel and connected to the chamber system. James McLellan, another diver coordinating activities from the drill floor at the time of the accident, received Hammond in the entrance lock. McLellan described Hammond as appearing “very cold, very tired and stressed.”
Pettit had blown McLellan down to decompression depth in the chamber, anticipating his joining Hammond after the bell had been raised. It is assumed that the divers proceeded shortly after to complete the final wire-cutting task after ensuring that communication issues were resolved.
The puzzling lack of any identifiable malfunction or equipment failure makes this a particularly enigmatic case. All primary systems, including the carbon dioxide scrubber and the soda sorb, appeared to function correctly. Further, Dave Hammond’s testimony that the gas quality seemed uncorrupted adds another layer of complexity. The absence of electrical faults despite the “strange high-pitched electrical noise” heard by Pettit also deepens the mystery.
In such circumstances, the inquiry would likely consider various less obvious factors, such as human error, psychological factors, or unanticipated interactions between otherwise functional systems. Investigators would need to explore other avenues without any technical malfunction to explain Hoffman’s condition. Possibilities could include diver panic, an undiagnosed medical condition that might have manifested under the extreme conditions of deep-sea saturation diving, or some other form of human factor that could have led to the tragic outcome.
Considering a theory about the high-pitched noise potentially caused by Hoffman’s headset falling into the water, one might wonder if this implies that something happened to cause Hoffman to lose control momentarily, although this still wouldn’t explain how or why he ended up in the trunking.
Dr Hendry, the medical examiner who performed the autopsy, offered a plausible yet speculative theory that doesn’t rely on equipment malfunction or external factors such as gas toxicity. The idea of syncope (fainting) brought on by rapid postural changes could indeed be a factor in this enigmatic case. The confined space and challenging environmental conditions inside the diving bell could exacerbate the effects of rapid postural changes and over-breathing, making fainting more likely. Over-breathing or hyperventilation also opens the door to considering other psychological factors. Anxiety or stress, though not necessarily extreme, could potentially cause a diver to hyperventilate, leading to a drop in CO2 levels in the blood and making one more susceptible to fainting.
Given that Hoffman was described as communicating clearly shortly before the event, this seems less likely unless there was a sudden, unreported onset of stress or panic. Closing one’s nostrils to clear one’s ears—a technique known as the Valsalva manoeuvre—can also have cardiovascular effects, including a transient drop in blood pressure, especially in an environment with varying pressure conditions like a diving bell. Still, this is a routine action for divers, making it less likely as a sole reason for fainting unless combined with other factors.
The mystery may never be fully unravelled without evidence of equipment malfunction, environmental hazard, or medical predisposition. It’s a grim reminder that even with advanced technology and safety protocols, the extreme conditions of deep-sea diving present risks that are not fully understood. The unfortunate event remains a grim chapter in the annals of underwater operations, shrouded in unanswered questions.
07 February 1978
David R. Hoover
Diving in the Norwegian sector to a depth of three hundred and five metres for Taylor Diving and Salvage Company, David started his final dive from a Brown and Root barge. There have been several reports as to the cause of the twenty-eight-year-old American’s death. Still, the latest, written in 2003, found that he had been put on a fifty/fifty oxygen-helium mix, which would have resulted in the partial pressure of oxygen equating to sixteen bar.
21 February 1984
Tom Mackay and Dave Bowmar
Due to incorrect breathing gas, David Bowmar and Thomas Mackay would both die after performing a welding test in a hyperbaric chamber at Sub Sea Offshore’s base of operations on Greenwell Road in Aberdeen.
Thomas (Tom) Mackey, a twenty-eight-year-old ex-Glasgow Shipyard welder, died from low O2/anoxia in a chamber pressurised at only nine metres deep after welding trials. Experienced air diver David (Dave) Bowmar, working for Sub Sea Offshore, was in the same chamber on this tragic day. Dave was still alive when the test chamber was brought to the surface. He was rushed to hospital but sadly succumbed later that same day.
The accident was initially reported as a nitrox dive, then said to have been the start of a saturation dive. However, it was most likely an air dive where the compressor put too much pressure into the divers’ Divator (AGA) full face masks. To adjust the pressure, the technician turned off the supply, and the supervisor then switched to a high-pressure (HP) gas quad. The air supply was changed again when the compressor was back online, but the divers were unconscious by then.
The chamber was immediately vented off to surface pressure, but Thomas was already dead. His dive partner Dave was still alive and transported to a hospital. The HP gas quad (bank), colour-coded pink but labelled twenty-one per cent oxygen, contained virtually pure nitrogen upon testing. The dive supervisor neglected to analyse one of the gas mixtures to the diving system, and in the course of the simulated dive, Bowmar and Mackey were not fed air as intended but pure nitrogen. Sub Sea Offshore and the company that supplied the gas were prosecuted under indictment and, after pleading guilty to the charges, paid £2,500 and £1,000, respectively, for the dual fatality.
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