Design and Engineering
PCCI, Inc. was tasked by Naval Facilities Engineering & Expeditionary Warfare Center (EXWC) to install an array of ten hydrophones off San Clemente Island in southern California. The array was installed in approximately 1200-ft of water and is connected to shore via cable. PCCI was additionally tasked with repairing the onshore cable landing structure to ensure longevity and operability of the new and existing cables.
Mobilization
San Clemente Island is quite remote and projects there require careful delivery of equipment, materials, and personnel. The island is about 80 NM from San Diego and 90 NM from Port Hueneme, thus, traveling to the island requires a full day by ship. Equipment for the shore work was mobilized in Ventura, loaded on a truck, and sent on a barge from San Diego. Dive equipment was loaded onto the dive vessel in Santa Barbara and the cable array equipment was loaded on the cable laying vessel in Port Hueneme
5 km
Cable laid along seafloor
3
Support Vessels
32
Personnel Onsite
July 2021
Completion Date
62
Material Suppliers and Subcontractors
Shore Installation
The dive vessel and shore team made repairs to 13 stainless steel cable trays which were each 10-ft long. The lids of the trays were removed in preparation of the new cable installation. Upon the arrival of the cable laying vessel, a team of 14 onshore personnel orchestrated the cable pulling operation in tandem with the vessel. The tasks of the crew included equipment setup, mooring logistics, systems testing, and (most importantly) safety. The divers finished the task by installing new anodes, stanchions, and anchor bolts to the cable trays.
Cable Lay
After the cable was secure ashore, the crew of cable laying vessel began following a planned route to lay the submarine cable. The cable laying tasks required coordination between the vessel’s dynamic positioning system and the cable payout rate to control the tension in the line and total cable length. The cable was fed from an open-top 40-ft container through a cable counter which indicated the length of cable paid out. 5 km of cable was laid along the seafloor.
Hydrophone Array Installation
Once the cable laying vessel was in the correct position, a 12,640-lb anchor was lowered over the stern of the vessel. The anchor is used as the base for the array which extends nearly 1,100-ft toward the surface where a sub-sea buoy maintains tension. The hydrophones were carefully attached as the array was lowered to the seafloor. A total of 10 hydrophones and an instrument pressure vessel were installed.
