By Dave Bazowsky
CHS Engineering Project Supervisor
Part of the Great Lakes Bottom Mapping Working Group Winter 2021 Underwater Update newsletter. Subscribe here.
In July 2020, the Canadian Hydrographic Service (CHS) solicited interest, through Public Services and Procurement Canada’s Hydrographic Services Supply Arrangement, to conduct a multibeam survey in Lake Superior. But this wasn’t just any contract for the provision of hydrographic services. Rather, there was one caveat that made this solicitation different from any others to date. The statement of work for this contract stipulated that the service provider must use commercial off-the-shelf autonomous technology instead of a conventional survey launch or ship.
The focus area of this survey was a 7.5 km by 100 km portion of a secondary low impact shipping corridor directly south of Thunder Bay, abutting the US border. This location was used to simulate an Arctic shipping corridor, for future plans to utilize autonomous vessels in the Canadian Arctic. Depths within the area ranged from 30m to 300m. Of note, this area also coincides with a portion of the world’s largest National Marine Conservation Area.
CHS entered into a contract with IIC Technologies Inc., who partnered with XOcean Ltd., utilizing their XO-450 Autonomous Surface Vessels (ASVs). In order to meet IHO Order 1A survey standards, the vessels were equipped with Kongsberg EM2040C sonars and Applanix WaveMaster inertial measurement units (IMUs).
These ASVs are the approximate size of a car and roughly 750 kg each. They were remotely monitored and controlled 24/7 via a satellite connection from various locations in Europe, by both ASV pilots (for navigation) and hydrographers (for data collection/data quality review). A minimal field staff component was on-site in Thunder Bay for data retrieval, ASV maintenance and support.
Of keen interest to the CHS was the ability for the ASV to employ ‘auto-swath’ technology, allowing automatic line adjustment in response to changing water depths. The use of auto-swath technology is instrumental in efficient multi-beam data collection. The lakebed in this area was relatively unknown, being last surveyed in the mid 1970’s, using single beam technology with 500m line spacing.
The CHS is hoping to leverage this experience going forward, taking several recommendations into account such that ASV technology may reach the level of maturity required for full implementation. One specific area of focus will be to evaluate the feasibility of adding payloads to the ASV in order to support additional in-situ marine science.
Not only will this modern dataset allow the CHS to update its navigational products in the area, it will also be consolidated into CHS’ NONNA-10 and NONNA-100 data series, available for free download in support of a broad range of non-navigational uses.
For further information, please contact Dave Bazowsky at dave.bazowsky@dfo-mpo.gc.ca.
