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Marine Casualty Report. Collapse and Sinking of Mobile Offshore Drilling Unit RANGER I in the Gulf of Mexico on 10 May 1979 with Loss of Life

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On 10 May 1979, about 2230, c.s.t., the RANGER I collapsed and sank in the Gulf of Mexico while jacked up on location in block 189L, 12 miles offshore Galveston, Texas. The collapse and sinking caused major structural damage to the upper hull, support mat and three support legs. Although these major components were raised from the bottom of the gulf and taken to Galveston, the unit was a total loss. The DELTA SEAHORSE, which was moored to the RANGER I, sustained minor hull damage as a result of being struck by the upper hull of the unit as it collapsed. Of the 30 persons aboard the RANGER I, 7 were killed, 1 is missing and presumed dead and 18 were injured resulting in incapacitation in excess of 72 hours. This report contains the U.S. Coast Guard Marine Board of Investigation Report and the Action taken by the Commandant to determine the proximate cause of the casualty and the recommendations to prevent recurrence. The Commandant has concurred with the Marine Board that the proximate cause of the casualty was an existing fatigue crack in the RANGER Is stern leg. The Marine Board concluded that the fatigue crack existed for at least 300 days prior to the time the RANGER I entered the shipyard for repairs on 12 February 1979. The fatigue crack was not visually detected either by the American Bureau of Shipping ABS surveyor or the USCG inspector during the shipyard period. Subsequent to the casualty, ABS amended their rules for inspection of mobile offshore drilling units to provide for the non-destructive testing of critical connections of support legs at periodic intervals.

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  • Marine Engineering
  • Safety Engineering

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