A Marine Educator At Sea

Monday, July 16, 2012

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.

Abalone with signal flag and strobe light

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.

Detachable hook on telescoping rod

Attaching tag line

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.

Retrieval Crane

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.

Keep the tag line taut

Abalone on deck

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.

Sunday, July 15, 2012

It’s been another full day. We recovered the Abalone seismometer J65 slightly after midnight (00:10) from 165 meters of water. After moving north, the weather deteriorated. Offshore the Washington side of the Juan de Fuca strait the winds rose to more than 35 knots, coming in from the Northwest. The seas were high and steep, but we managed to recover YiM2 at 04:45 from 139 meters. (VIDEO LINK) The darkness added to the challenge, as you might expect. We cruised on to the next Abalone recovery site, but the sea conditions were too hazardous to attempt it. Instead, we continued moving north through the heavy weather.

Attempting to sleep in conditions such as these are difficult. The pitch and roll of the New Horizon keeps you awake, in spite of exhaustion. An added hazard is being tossed from your bunk to the metal deck. I placed my survival suit under the outer side of the mattress, creating somewhat of a solid hammock. To insulate myself, I put blankets between the bulkhead and my body. Needless to say, we didn’t get much sleep.(VIDEO LINK)

Because of the weather and our reduced cruising speed, it took us until 13:50 to arrive at Y1M1. When we recovered this Abalone, it was covered with spiny sea stars. We recovered the fourth Abalone of the day (J73) at 17:46 from 143 meters.

Saturday, July 14, 2012

Today we recovered three Abalone seismometers. The first one was Y1M5 (see chart for location) at 07:30 from 828 meters down. The second seismometer (J57) was much shallower. At only 56 meters deep, its structure was covered with barnacles, anemones and a couple of sea stars. The next seismometer (Y1M4) was recovered from 563 meters of water at 20:20.

Anemones on J57

As the day progressed, the wind and sea flatten somewhat, permitting observation of marine mammal activity. During the morning we spotted two humpback whales (Megaptera novaeangliae) lunge feeding, possibly on herring. Later (~19:30), we had the good fortune to watch a large pod (~200) of Pacific white-sided dolphins (Lagenorhynchus obliquidens) swimming with another pod (~100) of Pacific right whale dolphins (Lissodelphis borealis). They could be clearly identified by their lack of a dorsal fin and torpedo-like breaching behavior.

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’s acoustic release. The Abalone acknowledges by sending back its own acoustic signal. We then send a signal down to the acoustic release 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 (Y1M7) was 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 (Y1M5).

Dr. Robert Dziak contributed this cruise summary:

“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
successful”

“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 deployed the 24th seismometer at 9: this morning. The atmospheric pressure is dropping and the seas are rising, making the deployments more challenging. The roll of the ship increases the difficulty of both getting the seismometer to the rail and successfully releasing it over the side. We are heading back to Newport to pick up another anchor plate for one that we lost a couple of days ago. We’ll be doing a “touch and go”, without even putting out the gangplank. Fortunately, the last site is close to Newport.

At 9:50, seven of us met in the wheelhouse for a live Skipe broadcast to HMSC. Tracy Crews organized “Career Day” for high school students and we responded via two way video to student questions from the Hennings Auditorium. Our virtual presence was projected on its large screen.

Bob Dziak – Chief Scientist – Professor, Marine Geophysics, OSU,  – What are you studying out there? What’s it like working at sea?

Dave Ogorman – Marine Instrumentation Engineer, Wecoma – How did you choose this career?

David Gassier – Ocean Research Engineer, Lamont-Doherty Earth Observatory, Columbia University – What is your background? Is there a specialized degree in Ocean Engineering?

Del Bohenstiehl – Co-chief Scientist – Associate Professor – North Carolina State University – What do you like most about being a scientist?

Matt Fowler – Mooring and Instrumentation Engineer – Research Assistant, OSU – What is your background? What do you enjoy most about your job?

Martin Rapa – Development Engineer, Scripps Institute of Oceanography – What did you have to consider when designing an underwater seismometer?

Tag lines are used to stablize the deployment

Matt is struggling with a jammed quick release mechanism

Following the continental margin, the Wecoma cruised south at about 10 knots for most of the day. The seas picked up slightly, and there were light scattered showers. We deployed another Abalone seismometer at 4:30, and it was on the bottom by 5:30. We will be deploying the last Cascadia seismometer at 1: am.

Chasing rainbows

Thursday's Sunset

The seas are very calm this morning, making for an easy deployment of the Abalone seismometer. We are directly offshore from the mouth of the Columbia River, in a depth of 2678 meters.

Note shipping pallet left on deck

Watersking anyone?

Wednesday afternoon, October 19^th – Off the coast of Washington at the edge of the continental margin

We just deployed another Cascadia seismometer. It will take 65 minutes to reach the ocean floor, 2630 meters below. It will take another hour to conduct the acoustic survey, as the Wecoma cruises in a kilometer and ½ circle overhead.

Ready to be released

Wecoma's crane is lifting the seismometer over the side

It takes at least 5 crew members to deploy a seismometer