When 24 year-old tanker broke up and split in two in the Bay of Biscay on December 12 last year - spilling 15,000tonnes of her cargo of heavy fuel oil - few initially anticipated that Erika would join the litany of major casualties that have influenced the design, construction and operation of oil-carrying tonnage. The volume of oil lost from Erika was less than 7% of that spilled when Amoco Cadiz grounded on the rocks of Brittany in 1977, and yet this latest accident has stirred at least as much, if not more, media interest and industry repercussions than the infamous grounding of 22 years ago.
According to a preliminary report issued by the French Transport Ministry's Marine Accident Investigation Bureau, break-up of the tanker was 'very probably' the result of structural weakness caused by corrosion. The Italian classification society's preliminary internal technical investigation indicated that:
- Erika was presumably lost because an initial crack in a low part of the hull below the waterline was misjudged and mishandled, allowing it to develop until the hull broke up
- The ship was not lost because of an overall hull girder collapse but because she suffered a progressive structural failure.
Concerning the origin of the crack, Registro Italiano Navale suggests the initial structural damage might have started from a defect and/or a brittle fracture in way of the bilge. The bilge is known to be one of the most problematic areas due to the presence of the bilge keel, welds connecting the internal structures to the shell, and welds of building blocks.
The Erika saga inevitably again brings into question the role and effectiveness of classification societies. IACS has already been stimulated to respond swiftly with measures targeting tankers (and bulk carriers) older than 15 years through upgraded intermediate surveys, annual inspection of ballast tanks adjacent to heated cargo tanks, and stricter control of transfers between class (only after a special survey by the gaining society). Nevertheless, the most stringent response has came from the European Commission, whose proposals reflect its belief that 'the application of the current international framework, including IMO rules, falls short of providing an adequate response to marine safety' and advocate action to 'discourage the use of old, technologically obsolete, and potentially unsafe ships.'
Its proposed 'EurOPA' regulations (echoing those introduced under the US Oil Pollution Act of 1990 in the wake of the Exxon Valdez disaster) call for the phasing-out of existing single-hull tankers in favour of new double-hull ships at an earlier age (by 2010 or 2015, depending on their design features) than that laid down in IMO's Marpol convention. Further port state control initiatives, enhanced surveys for tankers over 15 years of age, and improved information flows on substandard tonnage - also proposed by the EC - are accepted as valid measures by Intertanko. But the single-hull proposal is described as a 'draconian measure': it would bar around one-third of the world fleet of 2200 tankers from European waters.