Tracking the ocean floor

Rob White reports

This is the target we're looking at - the distinct outline of a ship, and next to it the huge "impact crater", made when she hit the bottom.

The wreck on the sonar screen

But you've still got to get your magnet in the right position over the haystack to have a chance It's enormous - but that's not so surprising when you consider that this ship, weighing perhaps thousands and thousands of tons, would have hit the bottom travelling at speeds of up to 20 knots. It's one of the characteristic signs of the presence of a wreck on the sea bed - one the main clues that experts like our Search Director David Mearns look out for.

But it's a long haul in front of the computer screens! On 'Bismarck', David and his team logged up 20 hours and more at a time tracking around the wreck, picking up shot after shot to tell the story of her loss.

Our experts were on hand too - as they are now - to give guidance and opinion on where to go and what to look for.

David and Lindsay

Yesterday David also had to squeeze in a TV interview with reporter Lindsay Taylor for 'Channel 4 News' - who are covering the expedition as part of Channel 4's wide-ranging commitment to the project. The interview was recorded "as live" - that is, in one go without editing - and then fed by satellite to 'Channel 4 News' in London. Here, producer Charlie Beckett edited in archive footage before it went to air.

This is the second of Lindsay's broadcasts fron 'Northern Horizon' - the first was a live report on the day he arrived - this time we pre-recorded to fit in with the search schedule.