Information provided by www.tristandc.com and gratefully used here.
tristandc.com has learnt that reports have circulated that loud bangs being heard as the oil rig sank were due to air bags exploding. We have asked for confirmation and have had this reply from Mark Board of Seaflex Ltd of Cowes, Isle of Wright which supplied the air bags (as we know that many of our regular visitors would like to know correct details of this saga at its end): Those bangs that were heard would not have been the bags which collapse gently as the external pressure increases with depth. Very likely to have been the cylindrical sealed structures (legs etc) that would have resisted the increasing external pressure until they suddenly imploded. It is this phenomenon that accounts for one of (what I think at least) the worlds most astonishing facts. When doing seismic surveys using explosives for the sound source in very deep water, the external water pressure is so great that even big charges produce only a wimpish ‘bang’. Solution, a glass sphere about 9″ diameter is scoured with a tiny scratch which propagates failure at a predetermined depth of say 4000m. When it ruptures, the implosion is so violent it make a bigger bang than dynamite. The most amazing thing is the sphere is made in two halves with ‘perfect mating edges’ and just held together with tape until it submerges. Thereafter, the increasing water pressure forces the two halves together so tightly it doesn’t leak until failure!