Current

Identification of Technology-Based Controls and Best Management Practices for Reducing Underwater Noise from Vessels

The objective of this project is to develop a report that identifies technology-based controls and best management practices for reducing underwater noise from vessels consistent with the requirements included in SEC. 3549 of the 2023 National Defense Authorization Act (NDAA), to submit a report to congress on effective vessel quieting measures. The report developed in this project will identify the current state of technologies and management practices available for reducing underwater noise from vessels in a manner that aids the larger marine community to understand feasible, existing and future potential methods with guidance on how such technologies and approaches can be implemented.

Testing a novel strategy for ship source level measurement in shallow water - University of North Carolina - Wilmington

The project consists of three tasks and final report:

• Task 1 will characterize sounds propagation in shallow (<25m) coastal waters by deploying a controlled sound source and a low-cost, horizontal, passive acoustic array perpendicular to the entrance of the Cape Fear River shipping channel in southeastern North Carolina. This task will assist in understanding propagation loss in this environment taking into consideration the depth, bathymetry, and seabed geo-acoustic properties. This is a necessary first step in measuring URN of commercial vessels in shallow water.
• Task 2 will investigate biological sound levels at this coastal ocean location and is necessary to the proposed study because measuring ship noise requires a firm understanding of background noise levels, which include other biological, physical, and anthropogenic sounds beyond the vessel of interest.
• Task 3 will then use the information obtained during Tasks 1 and 2 to measure URN of passing ships along the inbound shipping channel at this location using a vessel tracking approach as suggested by Southall et al. (2017). For Task 3, we will use the Automatic Information System (AIS) to identify the passage of commercial vessels and describe their acoustic characteristics using data collected by the horizontal, passive acoustic array.

Casco Bay Ferry URN Measurement

The objective of the study is to compare the underwater noise generated by the two ferries: an existing ferry with conventional diesel-geared propulsion and a new vessel with battery electric propulsion. These vessels are to be measured while the vessels are in service with equivalent operating conditions to allow direct comparisons of URN from the vessels. The data collected in this study will be compared with pertinent commercial standards and will be used to identify noise reductions that may be expected on future vessels when a battery electric propulsion system is used. The study will contribute to broader international discussions regarding vessel URN and inform vessel owners and operators of any potential noise reductions that could be realized through changes to existing or new build engines and/or power sources.

Crowley Tug URN Measurement

The objective of the study will be to compare URN emissions from a tug currently operating with diesel propulsion versus a new-build, replacement e-tug operating on battery electric propulsion in the same environmental conditions (route, season, purpose.) The study must measure the underwater sound pressure level of the vessels over several passes while engaged in varying operations in close-proximity to an underwater listening station(s) and using onboard noise sensors. In addition, the study should make use of and show alignment with, as appropriate, existing international standards and guidelines, class society notations, and/or indicators for measuring vessel URN. The study will contribute to broader international discussions regarding vessel URN and inform vessel owners and operators of any potential noise reductions that could be realized through changes to existing or new build engines and/or power sources.

Modeling Energy, Noise, and Emissions from Vessels

The Volpe National Transportation Systems Center (Volpe) will support the US Department of Transportation Maritime Administration (MARAD) Office of Environment and Innovation by providing technical support for a model of energy and fuel use, emissions, and noise resulting from maritime vessel traffic in the United States. This work will support MARAD's strategies to facilitate the decarbonization of the maritime transportation sector. The model will be used to quantify and map greenhouse gas (GHG) and criteria pollutant emissions from maritime transportation in the US. In addition, this work will investigate underwater noise sources from maritime transportation.

Completed

Environmental Capacity Assessment for U.S. Commercial Ship Design-Build Capabilities

The objective of this project is a comprehensive study to understand current U.S. capabilities for design and construction of low emission commercial vessels that also significantly reduce vessel generated underwater radiated noise (URN). The study will: evaluate current capacity to build to existing standards, guidelines, and regulations for energy efficiency, emissions reduction, and URN reduction; undertake outreach to design firms and shipyards to gauge design-build capacity, challenges, and opportunities, including integration of technology beyond current guidance and standards; and explore U.S. vessel orders to identify emerging opportunities to support the U.S. fleet. The deliverable is a report synthesizing the findings of the study components and outlining barriers, opportunities, requirements, and other emergent considerations, including research priorities, for the integration of low emissions and URN reduction measures into U.S. vessel design and construction.

Vessel-Generated Underwater Radiated Noise Comparison Study 

MARAD partnered with Noise Control Engineering to measure, assess, and contribute to understanding the underwater radiated noise from three tugs, one battery-electric system and two diesel engines. The goal was to compare the underwater radiated noise (URN) generated by the vessels and identify potential noise reductions that can be linked to vessel designs with reduced greenhouse gas emissions. The primary design advantage of the battery-electric system for underwater noise and greenhouse gas emissions is the use of battery power instead of diesel engines. At all transit speeds, the battery-electric system overall URN level is at least 6dB lower than the diesel powered vessels at comparable speeds. However, during simulated tug assist (STA) operations, the noise level is similar or louder than other vessels. Findings from this study may be applied to future vessels to help reduce acoustic impacts on marine life and reduce greenhouse gas emissions. The study is available here; the addendum with thrust comparisons is available here; and a high level summary of the work is available here.