No single cause led to the capsize of the AHTS Bourbon Dolphin with the loss of eight lives, with seven survivors, on April 12, 2007 says a report into the sinking released by Norway’s Justice Ministry, but Bourbon Offshore, which owned the vessel has been criticised for inadequately checking the vessel’s stability following an earlier incident and for not ensuring that the captain, Oddne Remøy, was sufficiently familiar with the vessel sand its crew before undertaking the operation that led to the capsize.
Key conclusions are:
• The vessel was built and equipped as an all-round vessel AHSV (Anchor Handling Supply Vessel). Uniting these functions poses special challenges. In addition to bollard pull, anchor-handling demands thruster capacity, powerful winches, big drums and equipment for handling chain. Supply and cargo operations demand the biggest possible, and also flexible, cargo capacities both on deck and in tanks. The “Bourbon Dolphin” was a
relatively small and compact vessel, in which all these requirements were to
• The company had no previous experience with the A 102 design and ought therefore to have undertaken more critical assessments of the vessel’s characteristics, equipment and not least operational limitations, both during her construction and during her subsequent operations under various conditions. The company did not pick up on the fact that the vessel had experienced an unexpected stability-critical incident about two months after
• The vessel’s stability-related challenges were not clearly communicated from shipyard to company and onwards to those who were to operate the vessel.
• Under given load conditions the vessel did not have sufficient stability to handle lateral forces. The winch’s pulling-power was over-dimensioned in relation to what the vessel could in reality withstand as regards stability.
• The anchor-handling conditions prepared by the shipyard were not realistic. Nor did the Norwegian Maritime Directorate’s regulatory system make any requirement that these be approved.
• The ISM Code demands procedures for the key operations that the vessel is to perform, Despite the fact that anchor-handling was the vessel’s main function, there was no vessel-specific anchor-handling procedure for the “Bourbon Dolphin”.
• The company did not follow the ISM code’s requirement that all risk be identified.
• The company did not make sufficient requirements for the crew’s qualifications for demanding operations. The crew’s lack of experience was not compensated for by the addition of experienced personnel.
• The master was given 1½ hours to familiarise himself with the crew and vessel and the ongoing operation. In its safety management system the company has a requirement that new crews shall be familiarised with (inducted into) the vessel before they can take up their duties on board. In practice the master familiarises himself by overlapping with another master who knows the vessel, before he himself is given the command.
• Neither the company nor the operator ensured that sufficient time was made available for hand-over in the crew change.
• The vessel was marketed with continuous bollard pull of 180 tonnes. During an anchor-handling operation, in practice thrusters are always used for manoeuvring and dynamic positioning. The real bollard pull is then materially reduced. The company did not itself investigate whether the vessel was suited to the operation, but left this to the master.
• The company did not see to the acquisition of information about the content and scope of the assignment the “Bourbon Dolphin” was set to carry out. The company did not itself do any review of the Rig Move Procedure (RMP) with a view to risk exposure for crew and vessel. The company was thus not in a position to offer guidance.
• The Norwegian classification society Det norske Veritas (DNV) and the Norwegian Maritime Directorate were unable to detect the failures in the company’s systems though their audits.
• In specifying the vessel, the operator did not take account of the fact that the real bollard pull would be materially reduced through use of thrusters. In practice the “Bourbon Dolphin” was unsuited to dealing with the great forces to which she was exposed.
• The mooring system and the deployment method chosen were demanding to handle and vulnerable in relation to environmental forces.
• Planning of the RMP was incomplete. The procedure lacked fundamental and concrete risk assessments. Weather criteria were not defined and the forces were calculated for better weather conditions than they chose to operate in. Defined safety barriers were lacking. It was left to the discretion of the rig and the vessels whether operations should start or be suspended.
• In advance of the operation no start-up meeting with all involved parties was held. The vessels did not receive sufficient information about what could be expected of them, and the master misunderstood the vessel’s role.
• The procedure demanded the use of two vessels that had to operate at close quarters in different phases during the recovery and deployment of anchors. The increased risk exposure of the vessels was not reflected in the procedure.
• The procedure lacked provisions for alternative measures (contingency planning), for example in uncontrollable drifting from the run-out line. Nor were there guidelines for when and in what way such alternative measures should be implemented and what if any risk these would involve.
• The deployment of anchor no. 2 was commenced without the considerable drifting during the deployment of the diagonal anchor no. 6 had been evaluated.
• Human error on the part of the rig and the vessels during the performance of the operation.
• Communication and coordination between the rig and the vessel was defective during the last phase of the operation.
• Lack of involvement on the part of the rig when the “Bourbon Dolphin” drifted.
• The roll reduction tank was most probably in use at the time of the accident.
• The inner starboard towing pin had been depressed and the chain was lying against the outer starboard towing pin. The chain thereby acquired a changed angle of attack.
The incident was investigated by a Royal Commission which held five open hearings and questioned 38 witnesses, including the survivors, officers from other vessels that participated in the operation, individuals from the owner company, the shipyard, the operator company Chevron, the drillrig “Transocean Rather”, the UK consultancy firm Trident, and The Norwegian Maritime Directorate and the classification society Det Norske Veritas. In addition the Commission has collected and reviewed a large quantity of documentation related to the vessel and the operation in which the “Bourbon Dolphin” was involved when the accident happened. The Commission has also had access to underwater footage of the casualty taken straight after the capsize and of the wreck in December 2007. Members of the Commission have held a meeting with the parties’ stability experts and gained access to material that the latter had collected.
In its report the Commission points out that it is not possible to show that an individual error, whether technical or human, led to the accident; rather, a series of circumstances acted together to cause the loss of the vessel. The Commission concludes that the proximate causes of the accident were the vessel’s change of course to port (west) so as to get away from mooring line no. 3, at the same time as the inner starboard towing pin was depressed, causing the chain to rest against the outer port towing pin. This gave the chain an altered point and angle of attack on the vessel. Together with the vessel’s current load condition, the fact that the roll reduction tank was probably in use, and the effect on the vessel and chain of external forces, caused the vessel to capsize.
It emerges from the report that a number of indirect factors have contributed to the accident. A combination of weaknesses in the design of the vessel, and failures in the handling of safety systems by the company, by the operator and on the rig, are major contributory factors to the operation of 12 April 2007 coming out of control. Overall, system failures on the part of many players caused necessary safety barriers to be lacking, were ignored or were breached, so that the vessel and crew were exposed to a risk that resulted in the accident.
The Commission also makes a number of recommendations in its report with a view to preventing similar accidents in the future. Although no structural changes are proposed for existing vessels, it is recommended that in the future requirements are made for the preparation of stability calculations for anchor-handling that will be subject to approval by the authorities. In addition, requirements are proposed for formal training of winch operators and a review of requirements for survival suits, plus placement and installation of rescue floats. The Commission also proposes measures to improve the companies’ safety management systems. Risk assessments must be improved, there must be routines for overlap of new personnel and identification of the necessary crew qualifications, plus the preparation of vessel-specific anchor-handling procedures.
The Commission also points out that the operators’ rig move procedures must be made specific for every operation and be simple to understand for those operating under them. It must be insisted that the operator and rig prepare risk assessments for the entire operation before it is commenced. When the operation is executed, safety and coordination must be continuously evaluated. The Commission also proposes that an attention zone be introduced along the anchor line, indicating a maximum distance within which the vessel shall remain when running out anchors.
Commission Report, preliminary English Version
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1) the boat was capable of doing the job, but because of the low stability not “fool proof”
2) the procedure of running the anchor out at full pull to keep the chain of the bottom does not make sense: 2 x 900 meter of chain, suspended from rig and tug, will never even reach the bottom in 1100 meters of water.
3) so the tug and the rig could have run out all of the chain with the tug just holding position anywhere in between the other anchor chains. After that run out along the track whilst the rig runs out the extension wire. (in fact what in the end the other tug did with the opposite anchor)
4) when you have a very low speed with the wind and current pushing you to port, giving port rudder (as is clearly visible on the pictures) only pushed you further to starboard.
5) the boat had a maximum affordable list of just over 30 degrees. When the chain came over, the boat almost reached this. but she came upright again. The starboard engine tripped, taking the load of. Then the starboard engine came back on line, and now the boat “fell” into the chain, leading hard to port, with even gerater force, and that was enough to capsize her.
My conclusion is that there were 3 factors: the procedure for running the anchor was not well thought of, the crew was very inexperienced, and the stability was too low to make the boat fail safe.
Take any of these 3 away, and the accident would not have happened (this time, but probably sometime soon later, as these 3 factors will came together again)
A remark about crew experience: with the amount of anchor handlers being built, this is a big problem.
The rule of having done 5 rigmoves does not mean much, as in each rigmove the tug does only a few anchors (two in this case), so a person can be qualified as a master after 10 anchors in his whole career.
Marnix van der Wel
Captain anchor handling tugs
Correction in my point number 4): when you have a very low speed with the wind and current pushing you to STARBOARD.. etcetera.