VENUS PROJECT-submarine cable recovery system

The deep seafloor observatory for the VENUS project will be a first complex observatory which uses retired coaxial submarine cable. Installation of the observatory requires three procedures; cable amputation, cable recovery, and re-installation. For the VENUS project, the cable reinstalling operation requires precise cable position control to put the observatory to target area. To solve the problem, Japan Marine Science and Technology Center (JAMSTEC) developed a cable recovery system consisting of a cable cutter, cable grippers and a pump unit. The pump unit which is electrically powered from underwater vehicle, generates hydraulic pressure to actuate the cable cutter and cable gripper. This system has an ability to amputate the cable at the deep seafloor and pick out to the surface. Cable recovery system was designed and manufactured to fit for underwater vehicles in JAMSTEC and has a capability to actuate in full ocean depth. Performances of the components are confirmed by pressure tests, amputation tests, gripping tests and strain tests on land or in pressure test tank. To ensure the total system performance, sea trials will be conducted by manned submersible at 6500 m depth seafloor.