Marpessa, a brand new Shell VLCC, on her first ballast voyage
was tank cleaning off Africa when an explosion occured in one of her center tanks,
killing two crew and injuring others.
Fire lines were damaged in the explosion.
They could not put out the fire.
Bulkheads began giving way; she sank stern first on 15th December.
This was one of the three big tank cleaning explosions in December 1969,
which led Shell to conclude that static electrictity created by
the tank cleaning jet of water was the probable source of ignition,
See Mactra and Kong Haakon VII.
This in turn resulted (eventually) in the requirement for inerting.
The flooding of 5C, Pump room and engine room is a bit puzzling.
Thanks to Karsten Petersen,
we have a photo taken from a distance of the ship burning.
Clear skies, wind no more than Force 4, no big waves.
The VLCC is on even keel, but much deeper than normal ballast.
At a guess, the explosion somehow holed 5C in the bottom,
and probably the longitudinal bulkheads as well.
Then the flooding worked its way aft.
But we need more info.
It is difficult to sink a VLCC in ballast in this manner.