An underwater survey of the wreck of a Peterhead trawler is expected to be undertaken this week.
The move comes against the wishes of families of some of the dead crew, who want to see the Trident raised.
Authorities want to establish why the Trident sank in 1974 off Caithness with the loss of seven crew.
Several of the families believe cutting into the vessel may destroy vital evidence and destroy the remains of their loved ones.
The wreck of the Trident was discovered by amateur divers five years ago, leading to an inquiry being restarted.
Several of the widows travelled to Downing Street last week and appealed directly to Prime Minister Tony Blair to halt plans to cut the wreck open.
This week a diving vessel paid for by the Department for Transport is to start its underwater survey.
Jeannie Ritchie, 65, who lost her husband and father, said: "By doing so, they will lose all the vital evidence on how the Trident sank and it would desecrate the men's graves."