Catch me if you can: OBS retrieval
We have had a very bust past 48 hours. We have been retrieving all our OBS instruments from the seabed.
Lookout from the bridge, can you spot the orange OBS?
The first step in the recovery process is contacting, or pinging, the OBS. This is to tell the OBS to start making its way back to the surface. To make contact with the OBS we drop a transducer overboard, which pings down to the OBS. We stop 3 nautical miles from the OBS drop off coordinates and ping it. We have to wait for a confirmation that contact has been made with the device to know that it’s travelling back to the surface. Sometimes we don’t make contact so we have to travel closer and ping it again from there.
Once we have contact and we know it is on its way up, we wait. The ascent time can be from 30 minutes to over an hour, depending on the depth.
Shortly before it’s due to surface the team heads up to the ship’s bridge (The room in the ship where the Captain controls the ship from). The ship has a 360° panorama view, which is important for lookout, as the OBS’s tend to drift as they rise and can pop up anywhere. Then we wait and scan the horizon looking out for sight of the OBS. A pair of binoculars is very handy here.
We do OBS retrieval at all times of the day. At nighttime the beacon flashes make it easy to see, but it’s tricky to gauge the distance.
The bright orange colour and the flags help finding the OBSs in the daytime (but it’s still difficult). However, we have been lucky with a number of them, as they’ve popped up close to the ship. The OBS also has a direct finder signal, which helps the ship find it.
The view from the bridge, waiting for the OBS to pop up
Sometimes it’s like finding a needle in a haystack… or a tiny orange football floating on the ocean.
To make it fun we’ve made a competition out of it. The “OBS Competition” Orange Buoy Spotting, gives points to the first person to call out that they’ve spotted the OBS. John Hopper won this round, with a total of 6 sightings.
Once the OBS is in sight, the Captain positions the ship so that the OBS will float past the starboard (right) side, where it is fished out and hoisted overboard.
The crew throw a hook to catch on the OBS to bring it in.
Bringing in the catch- the crew hoist the OBS onboard
While on lookout over the past 48 hours we have seen some really cool things:
On Monday night, whilst start gazing, we saw the SpaceX “Starlink” satellite array flying though orbit. They were released yesterday and were still very close together, so they resembled a train shooting across the night sky;
We saw some Northern Gannets (and remembered to take photos of them this time!)
We even caught a glimpse of some whale blows in the distance. We think it was the blow of a Fin Whale, as they are characterised by a prolonged tall blow and are found in the area. There was definitely a pair of whales, perhaps even a third one.
Tall blows of Fin Whales spotted from the bridge
Stay tuned for more updates from the PORO-CLIM expedition. As always, follow our social media acoounts. I'll leave you in the safe hands (wings?) of one of our OBS spotters.