The Magazine for Underwater Professionals
1st December 2017
UK-based ASV Global and TerraSond of the USA have announced the completion of the first ever seabed cable route survey supported by an unmanned surface vehicle. The survey route included various water depths and strong currents, while facing difficult wind and sea conditions in the Bering Sea offshore Alaska, the companies said.
The project was mobilised immediately following a 9000-kilometre nautical charting survey by TerraSond, of which 4750 kilometres (53%) was executed by an ASV Global C-Worker 5 autonomous surface vehicle. The cable route survey required a new payload including a hull-mounted multibeam sonar, a sub-bottom profiler and a towed sidescan sonar with 250 metres of armoured sonar cable. The payload swap on the C-Worker 5 was integrated, calibrated and demonstrated in the field in less than 48 hours, according to ASV Global. A total of 1220 kilometres of cable route survey lines were then successfully executed by the C-Worker 5 system, the company added.
Thomas Chance, chief executive officer of ASV Global, said: “This is a landmark achievement for ASV technology, and we are pleased to be supporting TerraSond in this effort. The fast re-tasking of the system from one type of mission to another illustrates the flexibility of the C-Worker ASV, and its consistent performance in difficult sea conditions further underscores the value of this highly efficient approach to offshore operations.”
Throughout the operation the C-Worker 5, designed for up to five days endurance at survey speeds of up to seven knots, was remotely monitored using ASV Global’s ASView control system from a station on TerraSond’s mother ship.
ASV Global has supported TerraSond for three consecutive years refining the use of autonomous systems in hydrographic survey applications. This year’s deployments follow on from a 2016 charting survey completed in the Bering Sea, off Alaska, where ASV Global and TerraSond marked an industry first by completing a 9578-kilometre hydrographic survey, 4213 kilometres of which were completed unmanned. Combined, these operations result in more than 10,000 kilometres in unmanned survey lines.
Tom Newman, president of TerraSond, said: “We continue to be impressed after several projects with ASV’s C-Worker 5 in a variety of missions. Together with ASV we have performed the first use in charting, first use in the Arctic, first use for a cable route survey and first to accumulate more than 10,000 kilometres in use. ASV’s team has risen to each challenge and the system has proved to be a reliable and cost-effective force multiplier, often doubling our production, operating in areas unsafe for a larger vessel and allowing multitasking on projects.”