It all started with the generous offer by Nortek Group to lend Seas Your Future an ADCP current profiler. I signed a loan agreement and soon after, two big peli cases were in my little car, backseat rolled forward, and ‘we’ were off to Bristol airport to join Pelican in Dublin.
The young voyage crew from Sail Training Ireland joined the next morning while I unpacked, watched the video manual and set up the ECO profiler to test run in a bucket of water…
The ECO is a hermetically sealed unit, charged by induction and connected via NFC and Bluetooth for programming and data transfer. It sits near the seabed, emitting a beam of sound waves upwards and receiving reflected sound. It makes use of the Doppler shift to calculate velocity of the current throughout the water column and can be deployed to a depth of 50 meters (find a simple definition of the Doppler effect here and a more technical one at NASA).
Our pilot joined in the afternoon and Pelican slipped around the corner to Dun Laoghaire for a night on anchor. The night was promising a blue moon, spring tide, sheltered bay and calm evening – could the conditions be more perfect for a first deployment?
The RIB was launched and with the help of bosun Sevastian, bosun’s mate Saul and watch leader Mara, we got the ECO into position and weighed down with an anchor and diving weights, we sunk it to the seabed.
It was a little nerve-wracking to turn around and abandon the instrument just like that. I’m more used to having science kit firmly tethered to the ship or at least a surface buoy. So the night felt long… eventually, I fell asleep, but woke at 4 pm and the pondering started: did I programme it correctly, wind up the cord ok, will it drift, will it resurface, will we find it?
On the dot at 08:30 the next morning it popped up exactly where we dropped it. Happy high-fives followed a successful recovery into the RIB and the ship.
At that point, we were all quite relieved that we got the ECO back on board. It was around that time when a call by captain Roy to give ‘him’ a name resulted in first mate Tamsin calling ‘him’ Bob (because he bobs up).
Another team effort was required to get the RIB back on deck and stowed.
The next excitement waited for us once I downloaded the data. This had to wait a little, as we were out of a mobile signal on our way, catching the wind north…
I was able to share with the ship’s crew the data from a near perfect tidal cycle of around 11 hours deployment, showing the changes in water temperature and depth, current velocity and direction.
This kind of data can be used in a wide range of applications, from calculating sediment cohesion around wind turbine pillars to tidal predictions and researching changes in ocean currents due to global warming.
Bob the ECO profiler has given me the opportunity to bring to life the otherwise relatively abstract subject of tides and ocean currents, to showcase to the youngsters on board some clever engineering and a state of the art oceanographic instrument.
With the support from all the Pelican crew, we keep deploying Bob – at the moment ‘she’ sits on the seabed off Aberystwyth beach until tomorrow morning.
A big thank you from me and our trainees on board to Nortek Group, in particular Iain White, Scott Gray and Jenny Ponsford for making it happen and support me with remote assistance.