July 24, 2006 Options

[Steve_Stevenoski]

July 24, 2006

Matt came into the room at 8:35 wearing mustang suit and protective gear. The plan for the morning was to deploy the gun cage to see how it behaved in tow behind the ship. The guns haven't been attached yet, but this would be a test to find the center of gravity so that when it was lifted by the crane and lowered into the water that it would be balanced. They would also deploy the single channel stream. This was just a test to work out the procedure for seismic group. They would find the best methods to use with the crane and securing the cage in a stable position behind the ship as it was towed.

Deployment of Airgun Cage



By 10:15 the cage had been deployed and secured back on deck, but the steamer, which is about 300 meters long, was still deployed. The bridge called down to the fantail that big ice was ahead. To avoid the ice they asked if they could turn without damaging the streamer. To avoid kinking or the streamer becoming slack, the order was given to make a turn with a half-mile radius and to maintain current speed to loop back onto the track that they had just made.

From 11:00 to 11:30 Mark did noise testing on the streamer. Every electronic devise produces its own unique set of signals, a little like the static that occurs between radio stations. Once you have identified the background noise that signal can be subtracted from the data collected by the streamer, producing "cleaned" data. By 11:50 the streamer was back on deck and testing was complete. They started to secure the 4 bolt guns and 4 GI guns to the frame after testing.

Talked with Harm at after lunch. His plans for the afternoon included a helicopter flight to deploy the seismic transmitters and to test the range of the units. By 12:45 the flight was cancelled due to weather (fog). At 2:00 the Coast Guard piloted a small boat from the ship to check out ice that was within a mile or so from the ship to locate a potential ice flow that they could place the gear on and would be safe to land the helicopter for a test run. They returned to the ship by 2:50 with ice flow selected and a plan for when the weather cleared.

For most of the rest of the afternoon I help with the setup of the compressors with Jay. I learned about the differences in characteristics if natural and synthetic pneumatic tubes. Jay showed me how to test for air and hydraulic fuel leaks without getting injured and how to attach the hoses properly to the compressor and valves.

At the start of watch at 4:00 the helicopter with the test gear left for the ice flow that they found earlier by bout. It was less than a half-mile off of starboard. Within five minutes the ice had drifted into the fog and it was nearly impossible to see the helicopter from the ship even with binoculars. During the time that the instruments were deployed the ice flow drifted nearly a half-mile. One of the things that will have to be done over the next few days is to determine a way to predict the location of the instruments on the ice after they have been deployed and have drifted out of the antennae range on the ship.

Test deployment of the seismic instruments on the ice



During the seismic refraction survey, a number of the instruments will be positioned in front of the ship. We will cruise toward the instruments then past them creating a long sting of data collectors. The farthest instruments will have to be picked up after they are out of range, collected by helicopter, and then redeployed in front of the ship again. The issue is to locate the instrument when it is adrift out of range of the ship.

During the test it was learned that the instruments have a difficult time communicating when there are two master receivers within antennae range. This should not be a problem when we are actually collecting data.

At 7:20 Bill flew Dale to Barrow to pick up some cabling that was need for the guns that finally arrived. Glen from BASC helped coordinate the pickup and transport of the equipment on the Barrow side. The flight returned at 9:00 and a number of us help offload the cables to the lower lab.

For the last few days, be have been letting the ice direct the course of the ship. Marcy and Matt H went to the bridge to set a few away points so that we could do a more complete survey of the seafloor using the Seabeam. At our current water depth of 40 to 50 meters the width of the swath covered by the Seabeam is about 250 meters or about twice the length of the ship. The way to do a complete survey is to have the swath paths overlap slightly, just like when you mow the lawn. We gave it a try starting at about 10:00.