Theseus (AUV)

Theseus is a large autonomous underwater vehicle built to lay fiber-optic cable on the ocean floor. It came out of Project Spinnaker, a Canadian defense research effort focused on placing underwater listening posts in the Arctic Archipelago.

The project began after a 1987 Canadian defense white paper emphasized Arctic sovereignty through nuclear submarines and passive subsea surveillance. The Defense Research Establishment Pacific, which specialized in Arctic acoustics, conceived Project Spinnaker. Because the deployment sites were in deep, year-round ice-covered waters, a new method was needed to run trunk cables from shore-based processing centers to the listening arrays. The lab turned to International Submarine Engineering Ltd. in Port Coquitlam, British Columbia.

Feasibility studies started in 1988 using ISE’s ARCS AUV as a test platform. In 1990, ARCS autonomously laid fiber-optic cable off Port Moody, proving the concept. Design of Theseus began in 1991, with construction from 1993 to 1994. Sea trials took place in summer 1994, followed by Arctic deployments in spring 1995 and spring 1996.

For the 1995 deployment, Theseus was broken into modular sections, flown to CFS Alert in C-130 Hercules aircraft, then helicoptered to Jolliffe Bay. There it was reassembled under a large heated tent. A 40-foot by 5-foot hole was cut through six-foot-thick ice, and the vehicle was launched and recovered horizontally for several under-ice test missions.

In spring 1996, Theseus returned to Jolliffe Bay for a full cable-laying mission. An acoustic array was placed on the seafloor at the edge of the Continental Shelf, about 180 kilometers from shore. Theseus delivered the cable to the array after just over 24 hours of running, then returned to Jolliffe Bay on command. A second cable-laying mission to another array failed when the trunk cable broke halfway, but Theseus completed the delivery maneuvers and returned.

The hull is 10.7 meters long, 1.27 meters in diameter, and displaces 8,600 kilograms. It is modular for transport by helicopter or Twin Otter aircraft. The bow section is free-flooding, holding obstacle avoidance sonar, a forward variable ballast tank and pump, an acoustic telemetry transducer, and strobe lights. The pressure hull has six modular sections containing batteries, electronics, and dry sensors. The payload bay holds fiber-optic cable packs.