R/V Polar Duke Farewell Tribute
in the Laboratory for Microbial Oceanography
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The Curse of the Icefish
by Joseph J. Torres
University of South Florida
Early on the first leg of the AMERIEZ winter cruise (June-July'88) we were attempting to do a set of Tucker trawls by towing the net through leads in the winter pack ice. The Tucker trawl was 2 m square at the mouth and about 8 m long, not a big net by pelagic net standards, but big enough to swallow a whole lot of ice. After a couple of stumbling attempts at deployment we figured out that a reasonable way to go was to launch the net in the usual way, but to tow with the A-frame in instead of out, so that the wire was in the shadow of the vessel. That way, growlers spinning off the stern of the vessel would miss the wire. Apparently, trawl wire - sea ice - boat motion interplay was something I hadn't done nearly enough thinking about before attempting to trawl in the ice pack. It is just those sorts of lapses that can come back to bite you on the butt. We had planned on towing between 200 and 400 m at a 2.5 to 1 scope so we were oscillating between 500 and 1000 m of wire out. The Duke's new marine tech, Jamie, was on the winch and since he hadn't much experience with net tows, he assured me that he would call the lab at the first problem. So, Joe Donnelly and I went down to the lab to prepare for the catch. We were communicating with Jamie every 15 minutes or so and were assured everything was ok on the fantail. During one of our conversations I asked what the wire angle looked like and he said "it's not much of an angle, looks like the net's way out there, I can still see it though, it's ok. " OOPS! We zoomed to the back deck and found that our net probably had been towing along the top of the ice pack for awhile. Two items immediately hit home. First, 500 m is not as much distance horizontally as you might think. I had been blinded by "vertical bias": 500 m seems like a pretty long way down. Second, small ice floes make wonderful fulcrums. As the ship moves forward, if the wire catches on one, it will pull the net up to the surface as effectively as a main trawling winch. I figured we had at least a ton of ice in the net. When the net arrived, we managed to get it on board (a bit of a struggle, that). It was pretzel-like in appearance. The crew of the Duke straightened out the bars, Shorty repaired the net, and we were back in business by the next day. Jamie of course is now a grizzled veteran and even then was a terrific tech. We did help him season the old trawling eyes, though. I had another trip aboard the Duke in '93 and brought a whole bunch of newcomers along as a field team. Every one of them said that the Polar Duke was the best vessel they had ever sailed on. I agree. We will miss the Polar Duke and wish her well. As Stig, the engineer on the '93 trip said, "Every ship has a soul, and the Polar Duke has a good one, she has a good soul". Tusentuk, Polar Duke.