JASCO Applied Sciences, in collaboration with BC Ferries (BCF) and DW-ShipConsult, are executing a project sponsored by Transport Canada’s Innovation Center (TC-IC) to provide results that will assist the International Standards Organization (ISO) in developing standard 17208-3 for the measurement of vessel underwater radiated noise (URN) in shallow water. Measurements in shallow water are difficult to perform because of the ways in which sound interacts with the seafloor and sea surface.
In assisting the ISO to develop standard 17208-3, this project aims to answer the question: What combination of sensors and analysis methods yield measurements of vessel underwater sound levels in shallow water consistent with those that are known to be accurately obtained in deep water using ISO Standard 17208-1/-2? The project has two phases: 1) development of a white paper that describes the issues associated with shallow water vessel sound level measurements and an associated measurement plan that address the identified knowledge gaps and 2) execution of the experiments and analysis of the collected measurements to address the knowledge gaps. Experimental measurements will be performed in shallow, mid, and deep water on the same BCF route (Tsawwassen to Swartz Bay).
The scope of this white paper is to analyze and illustrate the issues that complicate vessel URN measurements in shallow water, for the purpose of eliciting feedback from TC-IC and members of the ISO committee developing 17208-3 (Technical Committee (TC) 43, Subcommittee (SC) 3, Working Group (WG) 1 – TC 43/SC 3/WG 1). The white paper first provides an overview of the issues associated with making shallow water URN measurements; it then documents the results of acoustic propagation modeling numerical experiments that provide insight into where to measure, the appropriateness of different analysis techniques, and effects of sea bottom composition. The exposition concludes with recommendations for the hydrophone geometries to employ for at-sea measurements that will be performed in summer 2021.
After publication of this white paper, measurements using prototype moorings will be made in coastal waters off Halifax, NS. The input received from ISO TC 43/SC 3/WG 1 and the results of the prototype experiment will inform the development of the final measurement plan, which will be reviewed with ISO TC 43/SC 3/WG 1 in December 2020 to elicit further feedback and comments.