?? The US delegation at the IMO approved the concept 1997 - we had discussed the matter since 1991 - but the next day the head of USCG announced that tankers built according the concept approved 100% by the IMO could not enter US ports. The matter was later discussed in the US Congress where another USCG admiral suggested that the protection provided was less than double hull. It was decided to pursue the matter … but it was forgotten.
The secret of the Coulombi Egg oil tanker concept was/is the recognition that 80% of all tanker collision damages/spills take place above waterline so the protection should be located there … and not down at the bilge as required by double hull. I explain more at my website. USCG simply approved a sub-optimal protection (double hull) and refused to admit the mistake.