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Lessons to be learned in anchor handling

The Anchor Handling Tug Supply (AHTS) vessel Bourbon Dolphin, seen here entering Lervick on the Shetland Islands, just before being deployed on anchor handing duties northwest of Shetland, where she capsized.
Photo: shipspotting.com.

While struggling to set anchor # 2 for the drilling rig Transocean Rather on the Rosebank field, halfway between the Shetlands and the Faroe Islands on April 12, 2007, the supply vessel Bourbon Dolphin capsized with the loss of eight lives. In the wake of the tragic loss of a modern anchor-handling/tug/supply (AHTS) vessel on a routine job, the Norwegian government appointed an inquiry commission to establish the full chain of events that led to the calamity. The report, published on March 28, 2008, did not point to any specific reason for the loss, but found deficiencies in the procedures and safety management with all involved parties.

The rig move
The semi-submersible drilling rig Trans­ocean Rather was operating for Chevron on the Rosebank field in April last year, when five anchor-handlers were fixed for shifting the rig from Location G to I. The rig was owned by Transocean, a US-based company that for the planning of the move relied on the British consultants Trident. Because it was to be a complicated rig move in the open North Atlantic at a water depth of 1,100 metres, five large anchor-handlers were contracted for the job: Olympic Hercules, Highland Valiant, Vidar Viking, Bourbon Dolphin and Sea Lynx.
  The rig move was controlled by a Towmaster appointed by the operator, working in collaboration with the Offshore Installation Manager, the “captain” of the rig.
  The operation did not proceed entirely according to the Rig Move Plan. There were problems in extracting the anchors at Location G; equipment was damaged and had to be replaced. Being moved to the new location, six of the anchors were safely set at points 3,000 metres from the rig, but problems emerged with the last two, no doubt because of deteriorating weather and increasing currents.
  There was a SW wind of 30–35 knots blowing with waves of 3–3.5 metres in the morning of April 12, but increasing. The current was running at 3 knots in an easterly direction. The largest vessel, the Olympic Hercules, had problems with running out anchor # 6 against wind and sea in the morning and drifted some 400 metres off the stipulated anchor beam line.
  When the Bourbon Dolphin began to run out the last anchor, # 3, in a NNW direction at 0917 hours, she suffered a slow progress. Despite using her full towing power (180 tons bollard pull) and thrusters, her progress halted towards noon. At 1417 hrs, 1,200 metres of chain was out, but she had been thrown 185 metres off the anchor beam. The thrusters were beginning to overheat, and the engineer repeatedly asked the bridge to reduce output.
  An effort to relieve the Bourbon Dolphin by Highland Valour trying to “grapple” the chain at 1610–1625 hrs was unsuccessful, but led to a near-collision between the vessels. As the Bourbon Dolphin at this point was about 1,000 metres off the anchor beam, the Towmaster instructed her to head west to avoid fouling with the anchor # 3.

“The report found deficiencies in the procedures
and safety management with all involved parties.”

Blame all around
The commission found several factors contributing to the loss and points to deficiencies with all the relevant parties, from the designers to the company and the rig operators. Together, failure led to the lack, disregard or violation of the required safety barriers.
  The vessel: During the construction process, the A102-type vessel designed and built by Ulstein Verft was fitted with heavier winches than originally specified, but without corresponding changes to the stability documentation. This was known by the technical staff at the yard and the owners, but never conveyed to the officers on board the vessel.
  The crew soon discovered that the vessel needed fuel tanks well filled to remain stable.
  The company: The company was criticized for insufficient safety management systems. There were no established procedures for anchor-handling, no set routines for overlap during crew shifts, no identified requirements for competence beyond the STCW, no training programs for operation in deep waters and extreme conditions. There was no total risk analysis for rig moves, other than for personnel working on the cargo deck.
  The main point is that the internal quality system failed to locate these deficiencies. And neither did the DNV audit or, indeed, the Maritime Safety Directorate.
  The commission poses the issue whether these deficiencies were of such a grave character that the Bourbon Dolphin should had her safety management certificate granted at all.
  The crew: It appears that the top officers were not sufficiently experienced with anchor handling in deep waters. They had, however, found out about stability shortcomings and kept the fuel tanks as full as possible. The anti-rolling system was kept active during the operation.
  The operator: The commission found deficiencies in the operator’s procedures on several points. There were no clear criteria for risk analyses for planning and implementation of rig moves. In particular, there were not sufficient margins for static/dynamic forces from wind, weather and current during anchor-handling operations in deep waters. The weather requirements were not unequivocal, and the determination of vessel criteria with regard to bollard pull was not realistic.
  Operational leadership: The operation turned out to be more demanding and time-consuming than originally planned. The Rig Move Plan had to be departed from on several occasions, but not in accordance with the procedures set down in the operator’s manuals and the plans for the operation. The commission points to the role of the OIM (rig “captain”), who appears to merely have considered the safety of his own vessel, not the entire operation.
  The final part of the operation was characterized by severe failings in safety management. The Bourbon Dolphin tried actively to solve its problem, while the rig remained impassive and observant. Work on anchor # 2 began under marginal weather conditions, as proved by the Olympic Hercules’ struggle with # 6. The grappling by the Highland Valiant was carried out in an improvised way, without any risk analysis, and it failed. The OIM was not kept updated on the operation, and he did nothing to obtain information.
  Although there was no break of regulations, the commission finds it hard to accept that the operator’s representative (the Towmaster), who was in constant contact with the vessels, did not take the moral and human responsibility in ensuring that the Bourbon Dolphin was operating safely during the last phase of the operation. Also, both the Towmaster and the Bourbon Dolphin’s officers should have understood the consequences of the instructions and proposals given.

Proposals
In the closing, the commission points to several initiatives for improving the safety level during anchor-handling operations:

• Specific stability regulations for anchor-handling/tug/supply vessels.
• Consistency between construction details and certification.
• Requirements to the shipowners’ safety management system, including specific procedures for anchor handling for all vessels.
• Better overlap routines for crew shifts.
• Identify the requirements for competence and establish the relevant training courses.
• For operators to plan for realistic forces of nature and introduce unequivocal weather criteria for operations.

Dag Backa Jr. Editor, Norway.

Latest update 16-05-2008

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