The Ocean Ranger was a an extremely large and relatively well found semi-submersible which in the spring of 1982 was drilling for Mobil on the Grand Banks off the coast of Newfoundland.   It had eight columns. The corner columns from which the moorings were deployed were larger than the intermediate columns. Importantly to the enquiry, each of the columns contained three chain lockers which would be empty when the rig was moored, the rig being provided with a chain/wire mooring system. When on location all the chain would be on the seabed, and the wire would be connected to it.  Also key to the events which followed, the Ballast Control Room was situated in the aftermost intermediate column on the starboard side, below the level of the main deck.

It was a marine event, caused by a combination of poor design, bad practice and lack of knowledge. One of the many failings detailed by the enquiry was the curious diversity of responsibility for the rig. During the enquiry a number of former masters of the Ocean Ranger were interviewed and they testified that they had responsibility for marine matters without the authority to properly discharge their duties. The masters had no crew directly under their control and even the ballast control operators took their orders from the Toolpusher. The report on the sinking stated that he “had no knowledge of the ballasting system or the principles of stability. And yet the ultimate authority and responsibility for the safety of the rig and its crew rested in his hands”. 

The initiating event in the disaster was the weather, which turned from unpleasant to apocalyptic over the days up to 15th February 1982. On the previous evening the wind speed was about 70 knots and the rig was heaving alarmingly. Other rigs in the area, the Sedco 706 and the Zapata Ugland were both hit by large waves. The Sedco 706 was engulfed at about 1900 and the report says that the wave dislodged a small shed which was welded to the deck in the area of the drill floor, a point about 60 feet above the sea when the rig was at operating draft.  The Zapata Ugland was also struck by a large wave which washed over the helideck.

On the Ocean Ranger a large wave broke the port glass and flooded the ballast control room, dousing the ballast control board. As a result  valves in the pontoons started to open and close randomly, to the distress of the control room operators. They knew that they had a problem but they did not know how to solve it. Like many ballast control systems, the one on the Ocean Ranger was provided with solenoids which changed the electrical power into hydraulic power. A switch on the board would activate the solenoid which would open or close to allow hydraulic pressure to be exerted on the valve actuator, or to be removed, usually allowing the valve to close. Realising that they had to do something, some-one inserted a set of brass rods into the solenoids, apparently thinking that the valves would be closed, but instead the valves were opened. This allowed water to flow freely between the tanks, and since the ballast tanks in the Ocean Ranger were distributed along the lengths of the pontoons all the water ran from aft to forward. The rig gradually trimmed by the head until the chain lockers filled up and there-after, in the dark at three in the morning, on 16th February the rig disappeared from the radar screens of the ships in the area.

At five past one on the day of the disaster, only two hours before the sinking, the Mobil foreman requested that the Seaforth Highlander (The rig’s standby vessel) come to close standby. It was six miles away. In 60 foot waves one should remember that any movement of a ship in a specific direction, rather than just maintaining a heading which will reduce the possibility of structural damage, is something of a feat.

The report states that during the approach to the rig the Seaforth Highlander made ready the equipment it had available which might assist in the rescue. This, pathetically, consisted of a cargo net, a grappling hook, a boat hook and two heaving lines and two lifebuoys fitted with lines.

There was some inconsistency in the evidence from those directly involved as to what happened next, but the enquiry decided that the master of the Seaforth Highlander saw a  flare at   about 2.14 as the ship was approaching the rig, and that this flare had been fired from a lifeboat.

At 2.21 the Seaforth Highlander reported the sighting of another flare, had seen the lifeboat and was proceeding towards it. The Seaforth Highlander approached the lifeboat and decided to place the ship stern to wind with the lifeboat astern of the ship. In this way he would be able to maintain the heading, and would not be at risk of running the lifeboat down; a possibility if he had tried to carry out the rescue head to wind.  The witnesses said that the lifeboat was also head to wind apparently under power. The Seaforth Highlander now stern to the seas was manoeuvred closer to the craft and the seas breaking over the after deck were freezing instantly and making it difficult for the crew to do anything useful in their less than adequate protective clothing.

Just after 2.30 the Seaforth Highlander reported that the lifeboat was alongside. The crew on the deck managed to throw lines which the survivors in the lifeboat managed to attach, and at this time a number of men emerged onto the port side. It seems reasonable to assume that others had undone their safety belts, and had stood up, and obviously the bailing activities which had been going, on now ceased. These changes probably contributed to a loss of stability and as a result the lifeboat rolled slowly over throwing a number of men into the sea. The overturned lifeboat was close to the port side of the ship, and to reduce the possibility of injury to those now in the sea the captain stopped the port engine. As a result the ship began to drift away from those in the water, although the deck crew made valiant attempts to recover them, with some considerable risk to themselves since the seas were still breaking over the deck.

Meanwhile the standby vessels from the Sedco 706 and the Zapata Ugland arrived. The Boltentor was asked to assist in the recovery of the lifeboat, and the Nordertor was sent to monitor the rig itself, the Nordertor reporting the loss of the radar echo of the rig at three o’clock. There-after all three vessels took up the task of searching for survivors or bodies in the sea, but the report of the enquiry notes that “sea conditions and inadequate retrieval equipment frustrated all efforts to recover bodies”.

During the final but unsuccessful attempts to recover the lifeboat the captain of the Nordertor observed that there were about twenty bodies inside. Several floated out through a hole in the bow, and one was washed onto the deck of the ship. Over the following days the search continued for bodies, the fleet now enhanced by a number of other vessels, and by 20th February a total of 22 bodies had been recovered.

 
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