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CMG Joins National Marine Fisheries Service in Channel Islands Cruise
Guy Cochrane joined National Marine Fisheries Service (NMFS) biologists on a research cruise
from March 19th-25th on the R/V Robert Gordon Sproul. The scientists video-surveyed four
NMFS research areas in the Channel Islands off Southern California. Guy, Mike Boyle, and
other WRCMG personnel had mapped these areas previously with sidescan sonar. During last
March's cruise, video footage was collected using a DOE Phantom ROV (remotely operated
vehicle) equipped with a digital color video camera, four lasers, sonar, and depth-estimating
capabilities (see photo below). Divers surveyed shallow areas near shore and collected specimens of
rockfish.
National Marine
Fisheries Service personnel John Butler (left) and John Wagner
prepare ROV for deployment. |
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Configuration found
most successful for preventing umbilical from drifting into ship's propellers
during remote videotaping (not to scale). |
In deploying the ROV, the scientists tried several configurations for the "umbilical"-the
cable along which instructions are sent from the ship to the ROV and video images are sent
back to the ship. The trick was to keep the umbilical from drifting into the ship's
propellers, a problem that can arise when the ship is moving slowly to facilitate
videotaping. The most successful method was to run the umbilical down a weighted wire
deployed off the aft A-frame, with 20 to 30 m of free umbilical extending from the bottom
of the wire to the ROV. The weight was lowered to 5 to 10 m above the bottom. This configuration
(see diagram above) allowed the vessel to steam about slowly without severing the umbilical.
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June 2001
in this issue:
cover story:
Great Blue Hole of Belize
Channel Islands Cruise
Lake Mead Mapping
New Underwater Microscope System
Hurricane Display
Reston Open House
WHFC Outreach
Monterey Open House
School-to-Work Partnership
Acadiana Migratory Bird Day
SWICA-M³
Global Assessment of Geologically-Sourced Methane
Methane Hydrates
Metadata Workshop
Sue Hunt—Recycling
Coastal Stewardship
GIS 2001: Logan
GIS 2001: Massachusetts Bay
WHFC Visitors
Northeast Earthquake Hazards Map
June Publications List
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U. S. Department of the Interior | U.S. Geological Survey
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