August 26, 2018

The BP operated jack up Sea Gem became famous on 30 September 1965 discovering the first oil in the North Sea, off the mouth of the River Humber.
The Sea Gem was originally a 5,600 ton steel barge, converted to function as an oil rig by British Petroleum in 1964. The barge basically consisted of 10 steel legs which made it possible to raise the barge 15 metres (49 ft) over the water’s surface, as well as a helipad, living quarters for the crew of 34 and a derrick with associated structures.
In December 1965 the self-elevating drilling barge was located approximately 67 kilometres off the coast of Lincolnshire in the UK North Sea. On 27th December 1965, only two days after celebrating Christmas on the rig, at around 13:45 hours the crew commenced to jack the platform down. This process involved lowering the rig onto the surface of the water, in order to float it to the new site. A short time later, the passing freighter Baltrover witnessed the main deck lurch then fall towards port. The jacking system on two of the rig’s ten legs had apparently failed, causing the rig to fall sideways. As the radio hut was among the equipment that fell into the sea, the rig never sent out an emergency signal.
Most of the crew were rescued by the Baltrover or by helicopters that had been called out in the emergency. At that time there was nothing to been seen of the rig except for one of the legs sticking above the water and a mass of wreckage. Thirteen men were lost as a result of the disaster. This was the first drilling tragedy of North Sea.
As a result of a public inquiry into the accident,[2] several changes were made in order to improve the safety of oil rigs, amongst them the use of a stand-by boat, which would be able to help rescue crews in the event of future accidents, and the recognition of an Offshore Installation Manager.
This inquiry concluded metal fatigue in part of the suspension system linking the hull to the legs was to blame for the collapse. (Source and Dukes Museum and Wikipedia)