Cruise Blog by Frances Cooke: Day 6
July 12th, 2021
Text and photo: Frances Cooke (PhD Candidate in the Gas Hydrates and Free Gas Reservoirs research group at CAGE, working within the SEAMSTRESS project).
Back to site
We arrived back to site at 02:30 and the weather was less than ideal for seismic. We are limited with what we can do in poor weather, but waiting doing nothing is not a favourable option. We deployed the seismic in a slightly uncomfortable but a ‘safe to deploy’ sea state (winds 12-13 m/s). We started the deployment of the equipment at 04:00 then transited to the start of the survey line starting at 05:30. The line was complete at 08:30 just after our fantastic breakfast of pancake topped with berry jam and maple syrup.
The day shift (Vera, Mechita and Przemek) were up earlier than usual at 06:00, as the plan was to start the recovery of the OBS, but as it was too windy they had to wait until later on in the day. We decided the next best thing was to start a small multibeam survey. We plan to use the multibeam map to compare with the same data acquired in previous years, to see if there is any slump movement recorded in the sediments (pictured). We completed three lines of multibeam before cutting the fourth line short to recover OBS #5, and #6 once we had entered a calmer sea state.
Map of the bathymetry (seafloor topography) in the rainbow coloured depth scale, acquired during the small multibeam survey. Orange filled circles are the locations of OBS #5 and #6.
Recovering OBS #5
I hear Vera on the radio at 20:45 “OBS is rising. It’s at 730 metres” so I go up to the bridge to get ready with Truls and Hans (the Captain) to look for the OBS. Outside on the bridge deck are Andreia, Przemek and Mechita ready and waiting for the OBS to come to the surface. Attached to the side of the OBS is a flashing light and radio beacon that sends out a signal in one of four different frequencies, assigned to each OBS. The radio picks up the signal and makes a beeping sound when the OBS is close and Przemek and Mechita are then able to find the direction of the signal in relation to where they are standing on the ship. As the signal can only be picked up close to the ship, relying on sight is sometimes more reliable, so the more eyes on watch the better!
Andreia and Przemek holding the radio, looking and listening for the OBS once Vera has confirmed that it has reached the surface.
Read more about the SEAMSTRESS project here.
