Ocean Ranger - Causes and Effects

Causes and Effects

The remains of the rig were found by sonar search over the following weeks, resting in an inverted position approximately 485 feet (148 m) south-east of the wellhead, surrounded by major items of debris such as the derrick. The rig had capsized bow-first, turning over and striking the sea floor with the forward ends of the rig's pontoons. The United States Coast Guard Marine Board of Investigation report on the disaster summarised the chain of events as follows:

  • A large wave appeared to cause a broken portlight;
  • The broken portlight allowed the ingress of sea water into the ballast control room;
  • The ballast control panel malfunctioned or appeared to malfunction to the crew;
  • As a result of this malfunction or perceived malfunction, several valves in the rig's ballast control system opened due to a short-circuit, or were manually opened by the crew;
  • Ocean Ranger assumed a forward list;
  • As a result of the forward list, boarding seas began flooding the forward chain lockers located in the forward corner support columns;
  • The forward list worsened;
  • The pumping of the forward tanks was not possible using the usual ballast control method as the magnitude of the forward list created a vertical distance between the forward tanks and the ballast pumps located astern that exceeded the suction available on the ballast system's pumps;
  • Detailed instructions and personnel trained in the use of the ballast control panel were not available;
  • At some point, the crew blindly attempted to manually operate the ballast control panel using brass control rods;
  • At some point, the manually operated sea valves in both pontoons were closed;
  • Progressive flooding of the chain lockers and subsequent flooding of the upper deck resulted in a loss of buoyancy great enough to cause the rig to capsize.

A Canadian Royal Commission spent two years looking into the disaster. The commission concluded that Ocean Ranger had design and construction flaws, particularly in the ballast control room, and that the crew lacked proper safety training, survival suits and equipment. The Canadian Royal Commission also concluded that inspection and regulation by United States and Canadian government agencies was ineffective. In addition to key recommendations for Canada's offshore oil and gas industry, the commission recommended that the federal government invest annually in research and development for search and rescue technologies, such as improving the design of lifesaving equipment—a commitment that has been met in every fiscal year since 1982.

Further information: National Search and Rescue Program

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