Unlike their open-ocean cousins, harbor and coastal tug operators may not be aware of the environmental pressure to keep ships quiet…

Port communities and marine mammals alike can be significantly affected by ship-generated underwater radiated noise (URN). The evidence that URN is harming certain marine mammal populations is compelling, so many coastal ports – and their local, regional and federal governments – are considering short-term regulation of URN.

A working group within the UN has also met to consider formally classifying noise as a pollutant. The critical message is: What will tug operators, as active players in ports and harbors, do about it? Why should you care?

Is tug operation even a contributor to URN? Examining the ‘excitation-transmission-response’ physics of ship-generated noise, we find that propeller cavitation and impulses are principal sources of noise excitation. As high-powered vessels operating under heavily-loaded towpull conditions, yes – tugs must be considered a source for URN.

Then, what is the likelihood of impending regulation? In my opinion, the writing is on the wall, as voluntary “regulation” of URN has already become part of environmental protection activities. So, yes, we should care. And those companies that anticipate and plan for URN mitigation will have a competitive advantage with the least headaches.

Unfortunately, there is one big hurdle to broad and meaningful noise reduction – current engineering models for URN prediction are either woefully inadequate due to its simplicity or beyond the scope of naval architects due to its complexity.

The team at HydroComp has embarked on an initiative to resolve this hurdle with new research and development that will lead to a new engineering capability for naval architects to effectively assess and mitigate URN. This will leverage the ‘vessel-propulsor-drive’ simulation model inherent in our commercial design software and allow designers to solve URN problems before the ship hits the water.

Please join us in our efforts to solve this problem while we still have whales to protect!