''Stena Seaspread'' diving accident

Eighteen months after the Wildrake diving accident, the Thistle SALM was the site for another bell diving accident.^[1][2]

Stena Seaspread in the Thistle Field, circa 1980. Photo by Mike Allen.

Background

On January 21, 1981, Mike Allen,^{[lower-alpha 1]} 32, was supervising bell dive No. 342 on board the Stena Seaspread, adjacent to the Thistle SALM. Just after 10 o’clock that morning, Allen’s boss, dive superintendent Mike O’Meara stepped into the control van to ask how things were going.^[3]

Five hundred feet below, diver Phil Robinson had just returned to the diving bell to join his partner, Jim Tucker. Robinson had been conducting an MPI inspection on the SALM base when he ran out of ink. Topside was busy recharging his equipment while he took a short break.^[4][5]

The accident

The Stena Seaspread was a new vessel and its powerful dynamic positioning system easily counteracted the strong tidal currents running that day. But unbeknownst to Allen, the tide had drawn an excessive amount of umbilical off the umbilical winch, allowing the lifeline to foul on the SALM.^[6][7] With constant movement from the ship, a projection on the massive loading buoy chaffed a hole in the umbilical, piercing the main gas supply to the divers. Suddenly, Allen heard gas flowing through his panel. At the same time, the divers in the bell reported a drop in gas pressure. The time was 1015.^[8]

After confirming that there was indeed a leak in the umbilical, O’Meara asked Robinson to lock out again (using on board bell gas) to disconnect the swim line (a rope from the bell to the job site) and stow the inspection gear in the workbasket for recovery to the surface with the ship’s crane.^[9][10]

At 1041, during the recovery, Allen lost all communications, video, and hot water to the bell.^[11] The main umbilical had been torn completely in half.^{[lower-alpha 2]}

Supervisor Allen established wireless through-water communications with his divers and determined that they were okay. Then he conducted bell checks with the divers to ensure that specific internal valves were closed.

Unlike the Wildrake bell, which was lost in the dark on the seabed, the Seaspread bell was still suspended by its lift wire. The main winch was functioning, so, at 1122, Allen and O’Meara began hoisting the bell slowly to the surface, checking periodically with the divers to see if everything was okay.

At 134 feet from the surface, Robinson and Tucker ordered Allen to stop the lift. The bell was losing pressure.^[12][13] They didn’t know why, or where the gas loss was emanating from,^{[lower-alpha 3][14]} but now Allen had no choice but to return the bell to its working depth, which he did. At 1147, O’Meara declared an emergency and began notifying nearby diving support vessels to come to his aid. Once again, there was a race against time before the effects of hypothermia added two more names to the death list.

The rescue

Twenty miles to the south, the semi-submersible Uncle John was stationed beside the Brent Bravo platform just as it was during the Wildrake accident. When the emergency call came in at 1158, Comex Diving was monitoring a subsea pumping operation with an ROV (Remotely Operated Vehicle).^[15] The crew immediately recovered the ROV while the captain of the Uncle John began the process of dewatering the massive legs of the vessel.^[16] Normally it would have taken three to four hours to deballast the semi-submersible to raise it to transit depth, but the captain was accelerating the process by executing an emergency deballast, pumping water from the legs through huge fire cannons mounted on the aft end. As the Uncle John headed north on its rescue mission, huge rooster tails of cascading seawater trailed behind.

Three hours later the Uncle John arrived alongside the Seaspread to begin the rescue.^[17][18][19] Four hundred feet below the surface, Robinson and Tucker were keeping warm in very thick mummy bags and using breathing masks which not only scrubbed carbon dioxide from their respirations, but recycled their expired body heat. After the Wildrake accident, the diving industry recognized the futility of using space blankets as protection against hypothermia. Norway’s Underwater Institute conducted thermal studies to test survival systems for stranded divers,^[20] and Wharton & Williams Taylor Diving,^[21] in conjunction with a local technology institute, developed a new survival suit with high heat-retention properties. Robinson and Tucker were using those suits.

In the Seaspread bell van, Allen and O’Meara discussed their options for rescue. They knew where Robinson and Tucker were, but they couldn’t raise them to the surface. Very quickly it became obvious what they were going to do: “It was going to be a wet transfer,” Allen would say later^[22]—take Robinson and Tucker out of the damaged bell and put them into the safety of the rescue bell.^{[lower-alpha 4]} And so they did.

On board the Uncle John, Comex diving superintendent George Head lowered the rescue bell with divers Joe Puttnam, Richard Taylor, and Ken Iversen inside. In the gloom and darkness of 400 feet, they established a swim line between the two bells, took a hot-water hose to the stranded divers, warmed them up, then made the transfer by leading Robinson over first, then Tucker. For their part in the rescue operation, Iverson, Puttnam, and Taylor received the Queen’s Commendation for Brave Conduct.

Notes

References