In 1980, the LR-classed OBO Derbyshire foundered off Japan in typhoon Orchid. Tragically, 42 crew and two crew members’ wives lost their lives. The wreck site was located and subsequently investigated in 1997. A Reopened Formal Investigation (RFI) commenced in London in early 2000 and has shown a need for increased vigilance when operating large bulk carriers in extreme weather conditions. It is clear that great care should be taken to avoid any flooding, however small, in the bow in extreme weather conditions.
Evidence available indicates that green sea loadings on deck and hatch covers are highly influenced by ship speed, freeboard and trim. Therefore, operational prudence should be exercised. Results from model tank tests suggest that, in extreme weather, hatch covers built to the standards of the 1966 International Loadline Convention may – particularly on ships of Cape size dimensions – be exposed to green sea loads in excess of strength capability. A further test programme to validate these results is presently underway which may lead to a future requirement for hatch covers to be strengthened on some existing large bulk carriers.
A number of far-reaching recommendations have been agreed by a panel of experts serving the RFI. These highlight the need for shipbuilders, owners, operators and surveyors to pay particular attention to, amongst other aspects:
1. Ongoing maintenance and survey of hatch covers and ventilators
2. The securing devices of hatch covers being maintained carefully and fully utilised prior to the ship leaving sheltered waters
3. Careful maintenance of air pipes and ventilators and securing of their closing devices prior to encountering heavy seas
4. Effective closing of spurling pipes to prevent flooding of chain lockers and associated spaces
5. Ensuring that fore deck stores access hatches have back-up or appropriate securing means for storm conditions