Day 27 In heavy seas

Big swell breaks over the bow

Multi-beam swath showing a seamount during an earlier part of the cruise

Sunday, 22nd April 2012. After leaving King Edward Point on South Georgia we had set course back to the Falklands. The only science programme during transit was a seafloor survey using the ship's powerful echosounders - an EM122 multi-beam swath and the TOPAS sub-bottom profiler. The swath instrument is able to measure the exact depth of the sea and can establish the bottom topography in a narrow strip along our cruise track. This identifies subsea mountains ranges and points out canyons, ridges and other features. The sub-bottom profiler also uses acoustic pings, but at a different frequency, so that the reflected return signal can be analysed for the composition of the first few metres of seafloor. This helps to detect the type of sediment on the bottom.

All the data collected on the cruise will be transferred to databases that are shared with other scientists. The scientists planning the next cruise will pore over the swath tracks and TOPAS plots to find suitable locations to take sediment cores that give clues about past ocean circulation patterns or the climate changes in the geological past.

While the coring team is taking underway seafloor measurements the other science teams are winding up their operations. Equipment needs to be dismantled and packed up. The cruise is slowly coming to an end. But none of this is made easy by the sea conditions. Ever since leaving South Georgia we had been battling a heavy swell. Waves as high as 8 or 9 metres hit the ship constantly at such awkward angles that we were rolling and pitching heavily. Walking around the decks became a dangerous proposition. One moment you're walking uphill, the next moment you get flung forwards as you tumble downhill.

Trying to sleep in such sea conditions is also no easy task. The mattresses in our bunks come with straps, but they are only meant to hold the mattress in place should the bed need to be flipped up. Trying to strap myself in didn't prove too comfortable. So I opted to raise the side of the bed to stop me falling out in the middle of the night. But such board was available for the foot end of the bunk bed. When a particularly big wave hit us during the night, I crashed into the foot end of the bed and started sliding past it towards the cabin door, but just managed to cling on to the head board and stay in bed.

As ships go, the James Clark Ross is a comfortable ship, especially in the scientists accommodation, but still the heavy seas were getting to everyone. We were getting worn down by the lack of sleep, but the weather forecast looks better closer to the Falklands. Now it can't be too much longer until we hit calmer waters. Then we'll resume packing up and prepare for disembarkation.