Overcoming Challenges

Thursday, July 25, 2013
Ashes Vent Field VISIONS 13
Flattened oil-filled hose, VISIONS '13 Dive 1610

Flattened oil-filled hose on the horn of the ROV ROPOS Remotely Operated Cable Laying System (ROCLS), VISIONS '13 Dive 1610

Photo credit: OOI-NSF/UW/CSSF

1 Meter Scale Bathymetry at ASHES

This high resolution bathymetric map of the ASHES hydrothermal field shows the location of small, ~ 4 m tall, actively venting sulfide structures. The field is located near the steep western caldera wall. The field is likely fed by fluids circulating up along faults associated with this wall. 

Overcoming unexpected challenges is part of any oceanographic cruise. On Tuesday, 23 July, the VISIONS ’13 team was presented with an unexpected problem when imagery of cable deployed on the Remotely Operated Cable Laying System (ROCLS) during Dive 1610 at the Eastern Caldera, Axial Seamount site, revealed a flattened oil-filled hose. These “oily hoses,” as the engineers like to call them, should be nice and plump to fulfill their role in remaining flexible and protective at the end of the cable with the connector that plugs into the node on the seafloor. A flattened-hose was an indication of something wrong.

The onboard team of ROPOS, scientists, and engineers and the onshore team of APL engineers with strong participation from manufacturer ODI's customer service team, diagnosed and eventually fixed the problem by testing for leaks and, finding none, refilling the hose with silicon oil and testing the hose once again.

In the meantime, to keep moving forward, another ~ 1900 ft-long cable was installed from the Eastern Caldera site running south, as the work on the hose was carried out on the deck of the R/V Thompson. Following ROPOS's returned to the surface and between-dive checkout (on-deck turnaround) ROCLS was put over the side again to carry the repaired hose down for deployment. Cameras onboard ROPOS revealed that the hose stayed plump all the way to the bottom, and so the cable was laid.

Part of what students learn by participating in the VISIONS at-sea expeditions comes from observing and participating in the discussions and decision-making processes when things do not go as planned. Check out the student blogs here to read what some of them have written about what they have been doing thus far on VISIONS ’13.

For many onboard, the night of 24 July offered the first chance to view the active hydrothermal vent field called ASHES while on a ship sitting one mile above. As part of the surveys for good landing locations for ROCLS and instruments on a seafloor made up of what are often sharp and glassy lava flows, ROPOS used its high-definition video camera to send back images of stunningly beautiful sulfide structures. Often shimmering behind outflows of extremely hot water, the structures were densely covered with tubeworms, clusters of limpets, and other life forms. Among those on board who were participants in the VISIONS ’11 cruise, which visited this same site in 2011, there were comparisons and discussions of what had and had not changed. Fortunately for our purposes of laying cable and finding good landing sites, the placement and character of the major structures had not changed, so the cable route as planned on shore need only a bit of fine tuning.

​Contributed by Nancy Penrose, RSN Communications Coordinator