UB38, a German naval submarine, was sunk to the east of the ‘Varne’ bank in the Dover Strait during World War One. Surveys conducted in 2005 showed that there were 23 metres of water over the wreck at the lowest astronomical tide. As the wreck posed a potential risk to deep draught vessels using the south west lane of the Dover Strait Traffic Separation Scheme, TSS, Trinity House decided to have it moved to deeper waters.
At about 1000, on 21st June, 2009, the Belgium registered self-propelled crane barge Norma was in position over the wreck. The master instructed the Officer of the Watch, OOW, on the bridge, by VHF radio, to switch off the propulsion motors. The OOW was the
second officer and he turned the steering control switch, which was on the Voith Schneider propeller, VSP, control panel, to the off position. He then called the master using VHF radio and informed him that the motors had been switched off. The second officer did not inform the engine room that the electric motors were no longer required.
At 1125 one of a dozen divers aboard entered the water in a full suit to replace a line marking the position of the wreck of UB38. About 3 minutes after leaving the surface he told the diving supervisor that he was having difficulty because of tension on the umbilical cord.
When he reached a depth of 20 metres, he reported that he could hardly move, and asked the diving supervisor if the surface crew were pulling on his umbilical cord. The diving supervisor replied that they were not and, when the diver remarked that he wanted to come up, the supervisor told him to let go of the shot line and surface.
As the diver started to ascend, he was pulled violently by his umbilical cord and the polypropylene rope towards the vessel’s stern. At the same time, the surface crew were unable to hold onto the diver’s umbilical as it tightened, and the coiled airline was rapidly whipped from the deck along with the polypropylene rope.
The umbilical cord ran free until it reached the last few coils of airline secured to a door on the vessel’s aft deck. At this point, the umbilical cord severed and communications with the diver were lost.
The supervisor immediately contacted the bridge on VHF radio and was told by the master that the VSPs were not running. The master quickly called the engine room and was told by the chief engineer that the VSP motors were running in neutral. The chief engineer immediately switched them off. The standby diver was deployed and a RIB was launched at 1137 to search for the now missing diver.
Meanwhile, the diver had been rotating violently and had realised that he was being dragged towards the aft VSP. He was unable to cut his umbilical cord but managed to turn on the air supply from his emergency bottle.
When the VSP finally stopped, he was about 3 metres away from the propeller blades. He was then able to cut himself free; he climbed above the entangled coil of umbilical cord and pulled himself to the surface on the polypropylene rope. The diver surfaced towards the vessel’s stern at about 1155. He removed his helmet and shouted for assistance. He was recovered from the water and, although suffering from shock, the diver was uninjured.
The two VSPs, positioned fore and aft and each rated at 1200 hp were driven by four diesel generators. Once running the propellers idled at 650rpm in neutral pitch. Although the OOW believed that the engines had stopped when he switched the steering control switch to the ‘off’ position, the propellers were still rotating. He did not know that there were only two ways to stop the engines: From the engine room or by using emergency stop buttons on the bridge.
There were ammeters on the control panel which showed that the propellers were still drawing electrical current and, therefore, still turning but he was apparently unaware of the importance of the ammeter readings. He had not been trained in the use of the equipment.
A similar situation recently occurred with the Tug Busier in which a cable caught in a ship’s controlled pitch propeller, which was still rotating with propellers set to neutral pitch, unknown to the tug personnel.
MAIB notes: “The VSP control system was installed between January and May 2008. On completion, the system, including the emergency stops, was tested to the satisfaction of the attending Bureau Veritas surveyor, master, chief engineer and company superintendent on 22 May 2008. No instruction manuals or familiarisation training was provided to the bridge team.”
No procedures for its use had been developed and no familiarisation training had been provided; Neither the OOW nor the master verified that the propellers were stopped or informed the engine room that diving operations were about to take place;
Referring to the ship’s Safety Management System MAIB says: “The procedures covered key shipboard operations and were supported by appropriate checklists. The SMS also contained a safe work instruction titled ‘Interference with diving operations (sic)’ which required the vessel to check all items on checklist ref.SCF-26-056 ‘Diving Subcontract’ before the start of diving activities to ensure that the procedures and documentation of the diving contractor were sufficiently robust. This checklist was not on board at the time of the incident and there was no other guidance or procedure on board regarding diving operations.”
The Norma was not in continuous operations and MAIB makes the point: “The implementation of a robust SMS is undoubtedly challenging when a vessel such as Norma is out of service for long periods and is only manned for specific projects. In such circumstances, there is inevitably a greater onus on the vessel’s shore management to ensure that the crew is familiar with critical equipment, and that procedures are in place for all ‘key shipboard operations’, prior to mobilisation. It is clear these fundamental requirements of the ISM Code were not met on this occasion.
ISM audits failed to identify diving operations as part of vessel operations: “Although the use of divers was central to the vessel’s employment, it was not identified as a ‘key shipboard operation’ by the vessel’s managers, and the absence of robust procedures in this area was not highlighted during external ISM audits” says MAIB.
Following the incident, Scaldis Salvage & Marine Contractors N.V, the vessel’s manager, and Northern Diving Ltd, the diving contractor took immediate steps to prevent a recurrence.
Details of the incident and lessons to be learned have been issued to the shipping industry in a flyer published by the UK’s Maritime Accident Investigation Branch and by a safety alert issued to diving contractors by the International Marine Contractors Association, IMCA.
Recommendations have been made to the Maritime and Coastguard Agency, the Health and Safety Executive, the International Marine Contractors Association, the Association of Diving Contractors and the International Chamber of Shipping aimed at ensuring that guidance on the safe conduct of commercial diving operations involving merchant vessels is readily available. Recommendations have also been made to the International Association of Classification Societies and Scaldis Salvage & Marine Contractors N.V. to improve the effectiveness of safety management audits.