Friday, October 3, 2014

Riding big swells and crossing the Gulf Stream

On calm days, you could almost forget that you are in the middle of the ocean.  Its sunny and calm outside, and everything is stable inside.  People get lax and leave cups and other items on table tops unsecured and unattended.  And then some big swells come, and we all remember why chairs are tied to tables, furniture is nailed down to the deck and we use bungie cords and sticky pads to keep computers and other gear in place. Today we are experiencing swells up to 5 m high, in which the ship has rolled up to 25 degrees.  Unsecured items (including people in chairs!) are rolling all over the lab.
Meanwhile, we are also crossing the Gulf Steam, which poses it own challenges to our gear. Fishermen are particularly concentrated here, and today we deviated 10 km off of our profile to avoid fishermen and their gear.  The currents are also pushing our seismic streamer around.  In the ideal case, the streamer extends straight behind the vessel and quietly rides 9 meters below the water surface.  The currents today have pushed it to the side by 70 degrees from the ideal track, and the swells generate noise on the hydrophones.  However, even though conditions may not be ideal, it is essential that we collect data here for our science goals. We think that there are thick accumulations of frozen magmas beneath the Earth’s surface here that formed when the supercontinent of Pangea broke apart to form the Atlantic Ocean.  So we shall push ahead!
Annotated screen capture from our navigation system showing the ship, the streamer, our intended profile and our deviation.
 Donna Shillington from the R/V Langseth

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