Revelle Passing the Torch: Leg II Postscript

T_Tide_Logo_2015 Running a research program at sea involves the constant re-assessment of options: how to learn the most about the planet with the limited amount of time remaining in the cruise. As the time runs-down, the assessment effort intensifies. In every cruise a rather surreal moment is reached when one runs out of options: all remaining time is committed. The re-assessment process is history, the cards have been played and you get to see how much / whether you’ve won.

This happened for us last Sunday, at “Site 10” in 1100 m of water. The data coming in were just too interesting to walk away from. We decided to stay and keep the Fast CTD running until the “last-minute” of the cruise. Given our time requirements, the last minute was determined to be 03:00 Tuesday morning.

It’s a strange feeling to “turn off” a system that’s bringing in good data, providing an exciting view of the ocean 1000 m down. For the teams that kept the Fast CTD running 24-7 for the past three weeks it was almost like turning off the life-support system in a hospital setting. However, there’s nothing like extreme fatigue to minimize sentimentality and the morning watch got a three-hour break as the Revelle headed inshore to begin recovery of the T-SHELF mooring array.

WW#1 returns from 2500 cyclesFigure(1) A Wirewalker profiler comes aboard early Tuesday morning.

Tough Day at the OfficeThe effort began at first light. Ominously, the surface float marking the position (and key to the recovery) of the inshore doppler current profiler (ADCP) was missing. We would have to come back and drag a grappling hook to try to pull this instrument up.

Working progressively offshore, subsequent moorings came up with varying degrees of drama. By Wednesday noon, all moorings were aboard and we returned to the inshore site to drag for the errant ADCP. By 16:00 our time was up. We reluctantly left the instrument and headed for Hobart.

                                                                                         Figure 2. Tough day at the office: strategizing the search for the ADCP .

In that final evening at sea, the mooring team was involved in a frenzy of opening instruments, downloading data to computers, and archiving results. As the process unfolded the results proved gratifying. Drew Lucas’ two Wirewalkers each achieved ~2500 profiles, with all instruments aboard functioning properly. Nicole Jones’ five surviving moorings all worked well, with the exception of three thermometers lost during the recovery.

The archiving and packing effort was still going strong as the Revelle sailed up the Derwent Estuary Thursday morning for an on-time arrival in Hobart. As the morning progressed data archiving continued, the Fast CTD winch and boom were dis-assembled and packed, the T-Shelf mooring gear was offloaded, and bunk-rooms and labs were cleaned and readied for the Leg III team.Sun_Glint_Albatross

Somewhat strangely given the pace of the preceding weeks, by lunch-time there were people looking for something to do. It was time to disband. We gathered that evening with the ship’s crew and Matthew Alford’s Leg III team at the Hobart Customs House Hotel for a party worthy of Leg II. While totally successful, the party was reconvened Friday night to handle “unfinished business” and further brief the arriving Leg III group.

The “briefing” process was clearly effective: in the early hours of Thursday 5 March, after successfully recovering many of the TTIDE moorings, Matthew’s team dragged up the wayward TSHELF ADCP. What an effort!!

I have to thank Capt. Murline and the Revelle crew, as well as the US and Australian Leg II participants, for an incredibly successful cruise.


Rob Pinkel