July 14, 2022
by: Andra Papuc, P.Eng., Vince den Hertog, P.Eng.
The topic of underwater radiated noise (UWRN) and its impact on the marine environment continues to garner attention locally and throughout the world. Recently Robert Allan Ltd. completed a project funded by Innovative Solutions Canada to mitigate underwater radiated noise from escort tugs and reduce its potential impact on the local Southern Resident Killer Whale (SRKW) population. As part of Phase 1 of this project, Robert Allan Ltd. developed a parametric tool for estimating the underwater noise signature of ASD tugs and analyzing the effects of certain design choices such as propeller characteristics, propulsion plant arrangement and installation, and operational profile.
Building on an existing Robert Allan Ltd. tool for predicting atmospheric emissions called RAptures, the new UWRN module has led to new generation of the tool with noise prediction capability called TugEm. Crucially, TugEm is also designed to assess the relative impact of noise and mitigation measures on SRKW in terms of probability of detection, communication range, echolocation range, and sound exposure level. TugEm URN predictions were calibrated using a rich set measured noise data collected through the Port of Vancouver ECHO program initiative in the Salish Sea.
Phase 1 of this work aimed at completing a proof-of-concept version of TugEm which can now produce baseline UWRN predictions and assess the impact of early design choices. Future work to improve the accuracy of results from TugEm will include further systematic testing of local escort tugs, further development of the individual models within the tool (propeller model, machinery seating, propulsion choices, operational profiles), and optimizing the user interface.
Stay tuned for more updates on this important work!