by Penny Holliday
The good news last night – as we steamed towards our westernmost point of the section, just off Cape Farewell, Greenland – was that the water was clear of ice and we could get as close to shore as we had planned to go. The bad news was that it was 3am and very dark outside! This seemed to limit our sightseeing opportunities at this spectacular piece of coastline, but happily those of us who stayed up were rewarded with a lovely view of Greenland and some icebergs as the morning light appeared. Needless to say my photograph doesn’t do it justice!
As day was breaking we headed back out into deeper water to find the first of the OSNAP moorings that we plan to recover during this cruise. The conditions were clear and calm and not too cold, though the sky was grey and flat. However the day was brightened by the colours on deck: yellow, red, and orange of the mooring buoyancy spheres and people in their warm high vis coats and hard hats.
The photos show the sequence of a mooring recovery operation – an acoustic signal is sent to a device at the base of the mooring, telling it to release the large weight at the seafloor, allowing the whole string of instruments to float to the surface. The ship is positioned along side the mooring, which is now streamed out along the surface of the water, and the top of the wire hooked with a grapple. Cranes and deck winches slowly reel the wire in, while each instrument is removed as they come in, and taken into a lab for the data to be downloaded.
We successfully recovered two moorings today, giving us a whole year of precious measurements of the deep North Atlantic currents – tomorrow we lay a new set of instruments in their place.
Photos by Penny Holliday