Final stop!

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13 October 2023

Blog entry by Dinora Garcia Santacruz

We’ve reached our last working day, and it’s safe to say that our cruise has been a resounding success! Throughout the voyage, we accomplished several significant tasks, including deploying 9 moorings, 14 PIES as an array, and conducting 60 CTD casts. Despite unfavorable weather conditions on certain days, we successfully completed all of our objectives.

On our final day, we ventured into uncharted territory by engaging in a ‘Tow-Yo’ operation. For most of us, it was our first experience with this technique, which involves leaving the CTD in the water for an extended period while it is alternately raised and lowered (Yo-Yo) as the ship tows it at a slow speed, typically around 0.5 nautical miles per hour. The CTD is typically raised to a depth of 1000 meters before being lowered again. The Tow-Yo approach offers the advantage of profiling over a larger area, especially when using the LADCP. It also saves time by focusing solely on the range of depths under investigation, eliminating the downtime associated with recovery and deployment.

The Tow-Yo station kicked off at 12:00 and concluded at 23:00. Initially, there was some nervousness because the ship’s movement meant that the CTD was behind us rather than directly beneath us. This led to occasions where the length of the rope exceeded the depth behind us. Fortunately, the CTD altimeter functioned correctly, providing us with timely warnings about seafloor proximity and depth levels. It’s recommended to maintain a minimum distance of 40 meters from the seafloor as a safety buffer in case of emergencies. Everything went smoothly and hopefully we have collected a lot of nice data.

The CTD lab was abuzz with excitement as everyone eagerly observed how this new technique would unfold. Since there were no night shifts, we all remained awake until the CTD was safely back on deck. Once our mission was accomplished, we celebrated and headed straight to bed, knowing that our work was far from over.

Since Wednesday night, we’ve been in transit to our final destination, Ponta Delgada. The prospect of ending this adventure has left some of us feeling a tinge of sadness, wishing for a few more days at sea, while others eagerly anticipate returning home. Now, it’s time to pack all the instruments into containers, tidy up the labs, compile reports, and bid farewell to this incredible journey.

Tow-Yo map, MSM121
Study area and scheme of the Tow-yo station. Image courtesy E. Frajka-Williams
Final CTD deployment, MSM121
The instruments come back on deck for the last time on this cruise. Image courtesy Dinora Garcia Santacruz

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