A vessel of this size contains many different worlds, each overlapping but potentially invisible. I have been onboard for weeks and I still see people at meals who I have never seen before! There is far more going on here than I am aware of.
It’s a great experience to get these worlds to interact. Some of the scientists were taken on a tour of the inner workings of the vessel. As you would expect, it’s complicated! This different world starts at deck 2, a level I only usually visit to head to the gym. Here there is a small office with technical logs of all the machinery onboard. Beyond this it is like we are no longer on the same vessel! Whole rooms dedicated to things we take for granted; freshwater generators, air conditioning, waste water processing and at its heart a control room resembling a sci-fi movie from the 70’s (all cream panels, big manual switches and twitching needles on dials). From here every system can be monitored and adjusted, right down to disabling an individual plug socket.
There were a few surprising revelations. The limiting factor for how long we can stay at sea is not our fuel (the 1000m3 we carry could keep us moving at slow speed for a year) but the amount of food we can carry – we go hungry before the ship does. The endurance of the ship is therefore about 62days. Another interesting fact is that the fuel is actually used to run generators and the ships engines are electric. Where the propellers emerge from the hull is below the water line. It is very difficult to make a good seal against something that is spinning. A combustion engine produces vibration that would make these seals vulnerable, so electrical engines are used as they are far smoother.
A big thank you to the vessel engineers for taking the time to show us around their world.
On the scientific side of things we have fished our exploration of the Croizic canyon. Here we did find reef structures and managed to get plenty of photos and samples of well developed reef. We also found signs of human activity, a large amount of litter, usually in the form of plastic but also lost fishing nets. We found a trawl scar 16m wide passing right through one of the reefs. The difference was quite striking, a huge stripe of the reef reduced to rubble; thousands of years of development gone in an instant.
We are now at the Guilvinec canyon. Here we are conducting exploratory transects to plot the extent of the different habitats and to ground-truth others methods that we have used to estimate them previously.
While flying along at about 2m above the seabed the ROV has two high-definition cameras. One is facing forward; allowing us to drive and also nicely showing the three dimensional structures that extend from the seabed. Directly below the ROV is a downwards facing camera. This is not affected by perspective like the forward facing camera and allows us to accurately process the proportions and types of species seen along the transect. We can take screen-grabs from the camera and have a dedicated photographic camera if we see anything exciting.
Part of the dive was dedicated to sampling. We have quite a shopping list of samples wanted by both the specialist onboard and many more back home. We have to be selective due to time constraints and space on the ROV. To maximise both how many samples we can take and save time we use an elevator to return samples to the surface. This is a large container, almost the size of a small car that falls to the seabed. It has a beacon attached so the ROV can see where it is. It can then be loaded up with samples and commanded by the ROV to release its ballast and return to the surface. There we pick it up with a small rib and the crane. This allows the ROV to stay at the bottom working for very long periods while regularly sending us little surprises to work on. In fact, the constant arrival of samples has us all feeling a little wiped out.
We get a rest tonight though. The ROV needs 8hours to be prepped for the next dive so overnight the geologist get to take some 3m long cores of the seabed. They have identified some interesting hummocks; they would like to know if their inner structure is geological or ancient reef.
Update: Well, never a dull moment onboard! While I was writing this there was some commotion outside. In order to deploy the corer some spotlights had been shone on the water’s surface. At night this often attracts animals that can use the opportunity to feed. Slowly the whole food chain arrives. Larger and larger fish, squid and today we even had a small common dolphin arrive. He fed rather leisurely and we saw the occasional flash of silver as he struck at fish. The night is calm and he is close enough to hear his breath, a wonderful experience to end the day on.