Poor Internet connections prevented Bill from live-blogging the 2013 cruise, though he was able to capture some video (below) that provides an idea of what working conditions can be like at sea. You can learn about the season’s objectives and accomplishments on the Cascadia Initiative 2013 Cruise page.
The weather today cooperated with the successful recovery of three of our deepest deployed Abalone seismometers. The seas were calm, with 3 to 6 foot swells. The wind was out of the north, picking up to 11 knots as evening approached.
The depth of the seismometers’ deployment directly effects their recovery time. After an acoustic signal from the New Horizon is sent down to the Abalone’s release wire, we wait 7 to 8 minutes for the wire to burn through. We actively range on the Abalone as it ascents. Since the ship is stationary, the amount of time for the acoustic signal to travel up from the seismometer steadily decreases. The three Abalones that we recovered today (J43, J44 and J36) were deployed in depths ranging from 2654 meters to 2821 meters. The deepest seismometer (J36) that was signaled at 21:26, didn’t reach the surface until 22:10, and required a 44-minute ascent time. About twenty feet from the surface, a pressure-activated strobe is activated. There is also an orange flag on top of each Abalone, but since this particular recovery was at night, we relied on the strobe in order to navigate the ship into close proximity.
Once sighted and illuminated by spotlight, the New Horizon maneuvers to bring the Abalone along its starboard side. This is a delicate procedure, requiring a slow forward speed and bow thrusters so that we can bring the ship close enough to attach a tag line to the top of the Abalone.
One of us uses a telescoping pole with detachable grab hook attached to the tag line. Given the roll of the ship, large ocean swells and the vertical bobbing of the Abalone, this procedure can be very challenging. If we are unsuccessful, the New Horizon must turn into the sea for another attempt.
Once the first tag line is attached, another line from a telescoping pole and detachable grab hook is attached to the Abalone. The other end of this line is connected to the deck crane, which does the heavy lifting. Even after leaving the 300-pound weight on the ocean floor, the Abalone weighs over 550 pounds.
Immediately after the crane lifts the Abalone from the sea surface, another tag line is attached to its bottom. By maintaining tension with the first and third lines, the Abalone is prevented from colliding with the ship. The crane continues to lift, then turn aft, positioning the seismometer of the deck. Tag line tension is eased as the crane slowly lowers the Abalone and is secured to the deck of the New Horizon.
All of the data that the seismometer collected during its months on the ocean bottom is stored in the red data logger. The data logger is removed from the Abalone and quickly taken into the ship’s science lab to begin analysis.
Departed the NOAA’s MOC-P dock at approximately 16oo hours. The weather was clear with ocean swells coming in from the Northwest.
The fifteen instruments to be recovered were some of those that were deployed from the October voyage of the Wecoma. These are the Scripps Institute of Oceanography “Abalones”. Abalones are trawl-resistant, three component, battery powered ocean bottom seismometers, capable of being deployed in water depths of 50 to 6000 meters. We are recovering them via an acoustic release. After cruising to the proper latitude and longitude, an acoustic signal is sent down from the ship to “wake up” the Abalone. The Abalone acknowledges by sending back its own acoustic signal. We then send another acoustic signal down to the burn wire. The burn wire is an alloy of nickel and chromium. When an electric current is passed through it, the burn wire begins to oxidize. After about seven and a half minutes, the Abalone separates from its steel ballast and floats to the surface at about 60 meters per minute.
The first Abalone slated for recovery had been deployed in 1356 meters of water. After its 22-minute ascent, the strobe from the first Abalone was sighted at 22:05. The rough seas and high wind complicated recovery. The deck crew missed the first pass, and the New Horizon had a difficult time keeping the floating Abalone along its starboard side. Eventually we secured our first recovery to the deck at 22:45.
We will cruse through the night to our second station.
“The OBS deployment cruise was an unqualified success. Our
highly efficient team of sea going professionals was able to maintain a
brisk deployment schedule and completed all 25 ocean bottom seismometer
deployments within 8 days. We averaged 3 deployments a day, including
time for instrument surveys to derive their precise locations. The only
thing that suffered was our sleeping habits, but it was well worth it!
We also wish to express our gratitude to the Captain, crew, and Marine
Tech of the Wecoma for their hard work that allowed our project to be
“All 25 SIO and LDEO instruments were deployed with sites prioritized
prior to the cruise in consultation with the community to focus on
different scientific questions. This prioritized sequence was further
modified prior to the cruise to accommodate recommendations from the
Oregon Fishermen’s Cable Committee (OFCC), The Oregon Trawlers
Association, the Quilete and Quinault tribes, and the Canadian Trawlers
Association, all of which represents the various fishing communities on
the Oregon, Washington and Canadian continental margins. Of the 25
instruments deployed, one SIO Abalone instrument lost its anchor as it
was being deployed. Another Abalone was deployed in its place as a spare
anchor was sent to Newport during the cruise. We returned to port
briefly after deploying the first 24 instruments, and returned to the
site to deploy the lone remaining Abalone. All instruments will remain
on the seafloor until the summer of 2012.”
We have traveled north to test two Cascadia seismometers that were deployed earlier during the first leg during July. A specific frequency of sound (between 9 and 13 kilohertz) is sent down to check if the instrument package is working. Sometimes a fishing trawl can flip over the seismometer, rending it useless. If the instrument is working, it responds with a series of audio chirps that are picked up here on the Wecoma.
So far we have deployed five Cascadia and four Abalone seismometers. Another five are scheduled for deployment through the night.
Yesterday, we deployed three seismometers, two “Abalones” from Scripps Institute of Oceanography with the trawl resistant design and one from the Lamont-Doherty Earth Observatory (LDEO) called “Cascadian” which also has an absolute pressure gauge and hydrophone. These seismometers are generally deployed deeper along the continental margin.
Sea Grant's Bill Hanshumaker chronicles ocean research missions