MV Derbyshire - theories and factual evidence

In addition to our earlier posts published on this site, we would like to provide further comments and clarifications on the outcome of the Derbyshire RFI, and put forward a different possible scenario for the loss of the vessel. (Please see the attached DOCUMENT)

The 2000 inquiry maintained that heavy weather damage to a number of ventilators and air-pipes at the fore end of the vessel had allowed seawater to enter the hull’s forward spaces and cause the vessel to trim by the bow. It also concluded that this forward trim would have enabled heavy seas to break on and over the number 1 cargo hold hatch covers and subject them to significant loading. This ‘green sea’ loading was deemed to have exceeded the collapse strength of these covers causing them to fail, and leading to the flooding of number 1 cargo hold and hence even more trim. The process was said to have repeated on the number 2 and then the number 3 cargo hold hatch covers, and so on until the vessel sank.

The RFI loss scenario thus considered that the forward trim of the vessel (brought about by flooding of the stores spaces, chain lockers and forepeak) was the initiating factor in a chain events leading to the final loss.

Whilst the evidence indicating that the Derbyshire’s hatch covers had failed due to seawater loading is conclusive, the court was unable to demonstrate in a satisfactory manner that the vessel’s slight forward trim was indeed the causative factor of that failure.

Having noted the limitations of the MARIN model tests used by the RFI, we argue, on the contrary, that the forward trim that was taken into account would not necessarily have been sufficient in itself to bring about the tragedy.

The loss of forward freeboard due to flooding and trim, about 1.3m only (excluding flooding of the Fuel Oil Deep tank), was not of a magnitude that could significantly alter the ‘ballpark’ hatch cover loads expected to arise from the large waves and ship motions generated by typhoon Orchid. The hatch covers in this trimmed condition would still be about 8.9m above the sea surface and only about 630 mm below their normal position, with the ship in an undamaged but fully laden condition.

Therefore, the small trim by the bow could not realistically and satisfactorily explain the cycle of floodings and the resulting sinking that were suggested by the inquiry. Yet, under the label of unknown and unforeseen causes for the loss of the vessel, the RFI piled together and discarded many other possible alternatives.

Out of this class of unforeseen causes, we have now decided to present one alternative theory in which the spare propeller carried onboard the vessel, due to its position and location on the upper deck as well as due to its securing arrangements, becomes detached from its deck supports and wreaks damage to adjacent weathertight structures.

The damage to these structures, it is argued, would lead to flooding, the failure of the hatch covers, flooding and ultimately to the loss of the vessel.

Quite understandably, this alternative scenario, again, opens up discussions about liability and compensation, and this was something, which the RFI tried very hard to avoid.

(More details, explanations, diagrams and supporting evidence are contained in the attached DOCUMENT)

MV Derbyshire tragedy

The MV Derbyshire, a 91,655 gross tons bulk-carrier was was built in 1976 by Swan Hunter Shipyard, Teesside, for the shipping company Bibby Line. The vessel was registered at Liverpool and classified by LRS.

On 9 September 1980, during Typhoon Orchid, MV Derbyshire dissapeared off the south coast of Japan, with all hands on board (42 crew and two wives). She was, and remains, the largest UK ship ever to have been lost at sea.

The Report of the Formal Investigation (FI) held in 1987 first concluded that the loss of the MV Derbyshire had been due to a force majeure event, the vessel having probably been "overcome by the forces of nature in typhoon Orchid".

The wreck was eventually found in June 1994, during a search launched by the International Transport Workers' Federation and led by the American shipwreck hunter David Mearns. The search team were also able to deploy a ROV to survey the wreck and collect photographic evidence from the site.

Later on, using evidence from the underwater survey, the Investigation assessors purported - on the basis of a rope seen emerging from the Bosun’s store hatch opening and of an examination of the disposition of that hatch’s toggles - that the loss of MV Derbyshire had been caused by the negligence of the crew, who had allegedly failed to secure the hatch lid, which lead to fore end flooding and structural failure.

The discovery of the wreck prompted the British Government to re-open the Formal Investigation into the sinking of the vessel - investigation which began in April 2000. This time, the investigation reached the conclusion that the ship had sunk because of fore end flooding and structural failure, and as a result of inadequacies in the legislation in force at the time of build, and that the rope emerging from the Bosun’s store hatch opening was nothing more than post-casualty debris, thus absolving the crew of any responsibility for the tragedy.

The Investigation found that damage to the forward vents, hatches and equipment on the upper deck initiated the unfortunate sequence of events that led to the vessel's loss. Flooding of the vessel’s forward spaces through these damaged vents and hatches gave the vessel a trim by the bow, thereafter the main cargo hold hatch covers were subjected to seawater loading and collapsed – flooding number 1 hold first, then number 2 hold, then number 3, and so on until the vessel sank.

Several important questions, however, have remained unanswered:

1. The mushroom vents on the MV Derbyshire obviously failed. Were they therefore adequate?

2. The vessel had been issued with a Load Line certificate. But did the vents comply with the requirements of the Load Line Convention?

3. Did the construction and workmanship of these vents conform to the shipyard's or appropriate British standards?

4. Did the fillet welding on the windlass seat have adequate throat thickness and, was the workmanship satisfactory?

In due course, these questions and several others will finally be addressed.