Posted by: adorsk | January 14, 2009

Towing the Line: USVI to Bermuda

The Oceanus left St. Thomas on December 1st. This cruise was a two-part cruise involving towed instruments. We would start by testing the Scanfish, a new sensor package, in the sea around the Virgin Islands. Then we half of the science party would get off and the rest would do a plankton survey from St. Thomas to Bermuda.

Most of the science party was from WHOI, but there were a few others.

The chief scientist was DF. He studies ocean circulation and develops new sensors and observation techniques. On this cruise he and his team focused on testing the Scanfish.

DF’s team consisted of JL, BH, FB (from the second Red Sea cruise), AK, and NW, all from WHOI.

Also from WHOI were the plankton people. They were CB, MP, CP, and JE. They would use a special sensor called the Video Plankton Recorder (VPR) to observe plankton.

Since this cruise was originally going to be the third KAUST leg we also had HA (from the second Red Sea cruise) and YA from KAUST.

We also had NI, the head of the Oceanography center at the University of the U.S. Virgin Islands. And WHOI corporation member WP.

MP, BH, and CP are most definitely authorize personnel

MP, BH, and CP are most definitely authorized personnel (photo by AK)

The Gear

Both of the primary sensors we used on this trip were towed sensors.

The Scanfish was a new sensor that DF was developing. It looked like a yellow highway divider and would get towed behind the ship.

The ScanFish (photo by NW)

The ScanFish (photo by NW)

Testing the ScanFish at the dock (photo by MP)

Testing the ScanFish at the dock (photo by MP)

It was designed to do high-resolution surveys of water properties. This would let researchers observe how ocean circulation works at small scales.

The VPR was a sensor that photographed plankton. It looked like the love-child of an airplane and goalpost.

The VPR (photo by NW)

The VPR (photo by NW)

VPR on deck at the dock (photo by MP)

VPR on deck at the dock (photo by MP)

Its two arms had cameras that would focus on the space between the arms. The cameras would continually take pictures to record plankton as they flowed by. These pictures would be transmitted up the VPR’s wire into the lab where computers would process the pictures and figure out which plankton had been seen.

The VPR is incredibly powerful. Previously the only way to count plankton was by manually counting samples. Researchers would have to use microscopes to count and identify individual plankton. There is no better way to get seasick than by staring at sloshing water under a microscope. And it takes time. But the VPR records plankton continuously and automatically. A really great tool.

The Cruise

We started with a few CTDs near the islands and then put the Scanfish in. But soon there were problems. The Scanfish had stopped sending data to the lab. We brought it back on board for diagnosis. After a few hours of testing connections throughout the wire and winch, we found the problem. The connector that attached the Scanfish to its wire had chafed and cut the wire.

We had to figure out how to make a new connection. I worked late with JL to make a new termination. Fortunately it worked out and the Scanfish was working again. For the next five days we traded off between doing scanfish, CTDs, net-tows, and VPR deployments.

HA keeps a steady line on the CTD

HA keeps a steady line on the CTD (photo by MP)

MP and CP retrieving a net (photo by CP)

MP and CP retrieving a net (photo by CP)

HA & YK doing some 'sampling'

HA & YK doing some 'sampling'

On the 6th we went back to St. Thomas and dropped off FB, NW, HA, YK, WP, and NI at the University of USVI, and waited for the ship’s agent to deliver departure paperwork. While we waited NI took the rest of us to the university’s beach for a couple hours of snorkeling. What a treat! Just off the beach there were fantastic reefs. Colorful fishes swarmed over the reefs while giant sea urchins huddled bellow. Turtles and cuttlefish swam by. Bigger fish made circuits around reefs and occasionally stopped to nibble. It was beautiful. I don’t know how anyone at the university gets any work done with a beach like that on their doorstep.

We headed back to the ship and began our trip to Bermuda.  I was worried that we would see nasty weather on our way up, but were fortunate to have excellent weather again. We towed the VPR all the way without incident. We arrived at Bermuda on December 10th.

Other Pictures

The <i>Oceanus</i>, just off of St. Thomas

The Oceanus, just off of St. Thomas

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