Session: 06-15-03 Unsteady Hydrodynamics, Vibrations, Acoustics and Propulsion - III

Submission Number: 176391

Prediction of Underwater Radiated Noise - Opportunities and Challenges 

The underwater radiated noise (URN) from ships and offshore platforms has been demonstrated to exert an influence on, and in the most extreme cases, to cause harm to, marine life. In the Offshore and Arctic Technology sector, the relevance of URN extends beyond continuous emissions occurring during transit or dynamic positioning, encompassing short-term noise events that arise during exploratory surveys or installation operations.

URN from ship traffic in the world’s oceans has doubled approximately every decade since the 1960s. The relative increase is even greater in the Arctic Ocean. Given the ongoing increase in URN emissions, it is evident that measures must be taken to protect marine life.

The regulatory framework for constraining URN is undergoing rapid development. The International Maritime Organization (IMO) has adopted a voluntary approach to reducing the URN from commercial shipping. The effectiveness of this approach will be evaluated in 2026 after an experience building phase. The key tool is the ship specific URN management plan. Another approach involves the definition of protected areas subject to regional requirements. The IMO for instance published a guideline for Inuit Nunangat and the Arctic region in 2023. A further approach to addressing noise emissions involves the classification societies, who developed individual URN class notations.

Noise emissions into the oceans can be reduced through different strategies. Speed reduction is the simplest solution. Technological improvements at the source, such as the use of low-noise propulsion systems, can reduce URN without compromising performance. Re-routing helps to protect very sensitive areas. In any case, it is imperative to understand the extent of the noise generated by a ship or platform under specific operational conditions.

This presentation provides a concise overview of the various approaches to predicting URN. Empirical methods, numeric based predictions, full scale measurements and model tests each possess distinct advantages and disadvantages. The primary focus of the presentation will be on the prediction based on model tests. Under controlled conditions, investigations can be conducted, with a particular emphasis on the noise emission caused by the cavitating propeller. The noise impact can be significantly reduced by an appropriate propeller design or by implementing noise reduction measures. Since URN regulations will most probably differ regionally in future, the check for conformity with limits at single operating points during building stage of a ship is not meaningful. The HSVA provides the so-called URN footprint to give an overall picture of the noise caused by a propeller for the operating speed curve.

A number of proven tools are already available today for predicting underwater noise from ships and platforms. However, the specific areas of validity of the methods must always be taken into account.

Presenting Author: Lars Koopmann The Hamburg Ship Model Basin

Presenting Author Biography: Lars Koopmann is a project manager at The Hamburg Ship Model Basin, focusing on cavitation and noise. He has extensive experience in special projects and is jointly responsible for technical and strategic development in the field of cavitation. Prior to joining HSVA, he gained valuable experience working for a manufacturer of maneuvering technology for a period of six years. In this role, he specialized in noise and vibration, acquiring a comprehensive range of practical experience.
Lars Koopmann studied Naval Architecture and Ocean Engineering at the Technical University of Berlin. After completing his studies, he worked as a research assistant focussing on hydrodynamics. He lectured in ocean engineering for more than six years and inspired many students about the utilization and protection of the oceans.

Authors:

Lars Koopmann The Hamburg Ship Model Basin
Björn Carstensen The Hamburg Ship Model Basin