On Site to Install PN5A

Monday, August 06, 2012
Plan for OOI RSN Primary Node Installation
Close up of Grapnel

This closeup shows part of the grapnel, nicknamed "The Beast" by Cecile Durand, used to hook and recover the cable from the seafloor.

--Photo by Cecile Durang

Brian Ittig, OOI RSN Marine Operations Manager at the University of Washington, boarded the TE SubCom Dependable in Portland, Oregon, last Friday as Cecile Durand, OOI RSN Marine Maintenance Manager at the University of Washington, disembarked after Phase I of the Primary Node Installation work. Brian reports on work accomplished since the Dependable departed Portland on Friday, August 3:

After OOI RSN Primary Nodes 3A and 3B were loaded, positioned on the aft deck, and successfully tested, the vessel departed Portland and transitted to the Primary Node 5A deployment site in the middle of the Juan de Fuca tectonic plate. Segment 6 grapnel operations began as soon as the vessel arrived on site at 1200h PDT, Saturday, 4 August. The first task was to recover the end of cable Segment 6. Initial grapnel operations were successful and the ground rope was engaged in the second hook, or "jammer,"  in the grapnel. Approximately 6 km of cable Segment 6 were recovered, repositioned to the North, and "buoyed off" at 1330h PDT Sunday, August 5. This deployment of the cable end to the buoy will assist in future operations when it is time to bring the cable ends onboard the ship and join them to the node.

Next step was to transit to the Segment 5 cable grounds where grapnel operations began at 1500 h PDT. The Segment 5 ground rope was successfully engaged and the cable was brought onboard early in the morning of Monday, August 6. Approximately 12 km of cable Segment 5 have been recovered and are currently being re-positioned to the final cable route.

A bit of background on Primary Node 5A

The Primary Node 5A deployment site is in approximately 2850 m water depth. PN5A will be the first of three primary nodes deployed on the northern line of the OOI RSN cabled infrastructure. This northern section, which runs out to Axial Seamount, is comprised of approximately 530 km of cable.

The configuration of Primary Node 5A differs from the other primary nodes to be installed along the northern line: PN5A will be attached to three submarine cables, whereas the other nodes will be attached to two (PN3B) or one (PN3A). The additional, third, cable is a stub that will support potential future expansion of the cabled infrastructure and will enable adding more primary nodes without having to recover PN5A. Due to several factors, including installation configuration and water depth, the deployment of Primary Node 5A is expected to take seven days.

--Brian Ittig, OOI RSN Marine Operations Manager, University of Washington, onboard the TE SubCom Dependable

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