Exploring the deep
How do you find a wreck that's some 3,000 metres under the sea? At that depth, as well as being dark and cold, the pressure is very high. Apart from the occasional fish it is barren. No human being could survive the extreme conditions of this underwater desert.
Search Vessel - The Northern Horizon
The only way to explore the sea bed at such depths is by using equipment controlled from a ship at the surface. David Mearns of Blue Water Recovery is leading this expedition - finding out what happened in the epic battle between the German ship, Bismarck and the British ship, Hood. He will have at his command the latest technology. First, though, he and his team must do months of research.
Before setting off
The team start by finding out everything they can about the vessel and what happened on the day she went down. They use historical records, such as logbooks of every ship and reports from every aircraft that were in the vicinity of the battle, as well as photographs, eyewitness reports and any other material that relates to the event. In this way they build up a picture of the position of the ship and how she sank.
They need to find out what conditions they will face at the exploration site. Researching the weather, winds, currents and the geography of the sea bed, they discover that there is just one period of a few months in the year when it is feasible for the expedition to go ahead.
The team analyses every piece of information. They need to decide whether the data is reliable: was the witness an inexperienced member of the crew or a long-serving sailor? How accurate were the ships' instruments and what is the margin of error?
Finally, they have enough information to reconstruct the positions and movements of all the ships and planes in the vicinity of the battle on 24th May 1941. This gives them a reasonable idea where the wreck may be.
Plan of action
The next stage is to develop a search plan and gather together the sophisticated equipment they will need.
David Mearns' team has identified an area of 600 square nautical miles within which they expect to find the wreck. This is a massive area to search, but their state-of-the-art side scan sonar mounted on a remotely operated vehicle (ROV) will go up and down the site, in an action they call 'mowing the lawn' until it finds the ship. All the time, the sonar will send signals back to their survey ship, where computers will translate them into images.
Also mounted on the ROV are specialised cameras that can function as deep as 6,000 metres, and lights adapted to enable the cameras to take high quality pictures in these dark conditions. In turn, these pictures will be sent along a fibreoptic cable to the survey ship so the explorers can see exactly what the ROV has found, 3,000 metres down.
Side Scan Sonar - Explorer 6000