The most complex marine accident investigation carried out by the United Kingdom will involve two expeditions to the site of the sinking, off the coast of Japan, at a cost of pounds 2m.
A source at the Department of Transport described the quest yesterday as "like trying to fly through the Alps in a glider holding a pen-torch in your mouth as your only light".
The first expedition, due within the next month and lasting five days, is to fix the location of the stern by sonar mapping and possibly the use of a remotely operated submarine.
An expedition sponsored by the International Transport Federation discovered the bulk of the wreckage last year but could not identify the stern, which the federation suspects is at another wreckage site five miles away.
The second expedition, to last between three and eight weeks early next year, will entail a more detailed marine survey and may feature the descent of a manned submarine 4,300 metres (14,100ft) to the seabed.
The 90,000-ton British-owned Derbyshire sank in September 1980 in a typhoon while on the way from Canada to Japan, with the loss of all 44 people on board.
The ship was modern - four years old - and double-hulled, so the department believes the reasons it went down may hold lessons for the design and safety of other vessels.
The Derbyshire Families Association, which has led a lengthy campaign to force the department to investigate the disaster, expressed disappointment that it would not be represented on the expedition.
The Families Association argues that catastrophic failure of one of ship's frames - No 65 - caused the sinking.
But the expedition will consider another 12 suggested causes for the disaster, including failure of the hatch cover or engine.Reuse content