Recently, China Merchants Heavy Industry (Jiangsu) Co., Ltd’s newly-built wind power operation and maintenance vessel, IWS SKYWALKER, has completed the audit process related to the Silent(E) underwater noise notation, which means that the vessel has become the first commercial sea-going vessel in China to obtain the DNV Silent(E) underwater radiated noise notation.
IWS SKYWALKER is one of the six wind power support vessels ordered by the Norwegian owner in 2021. With an overall length of approximately 90 meters, the vessel is equipped with a 3D motion-compensated crane and motion-compensated gangway, a total of four sets of full-swing thrusters, both forward and aft, as the main propulsion system, as well as a lithium battery-based plug-in hybrid solution.
According to DNV’s specification, the measurement adopts the shallow water far-field test method, during the measurement, a high-precision hydrophone will be sunk from the auxiliary tug to the seabed, and the vessel to be measured will sail back and forth within a certain distance from the hydrophone in order to record its underwater radiated noise level data.
It is understood that the ship in September 17 this year began the trial voyage. September 22, the Silent (E) underwater noise measurement, the test was a succesfully completed, and on December 12 succeeded in delivery in Zhoushan waters. The final measurement results show that the ship’s underwater noise level meets the limits set by DNV Silent(E) notation.
The harmful effects of underwater noise generated by commercial marine vessels have gradually attracted attention in recent years. Many international organizations and institutions have issued qualitative or quantitative requirements to pay attention to or limit the level of underwater radiated noise, such as the 2023 Agenda for Sustainable Development issued by the United Nations, in which one of the 17 goals is the protection and sustainable use of the oceans and marine resources; The EU Marine Strategy Framework Directive (MSFD) includes underwater noise as an indicator; and the International Maritime Organization has agreed to a draft of revised guidelines for the reduction of underwater noise in commercial shipping.
In addition, some governments have introduced incentives, such as the Port of Vancouver in Canada, which offers up to a 47% reduction in port dues for ships meeting the DNV Silent(E) notation and corresponding standards. DNV’s Silent(E) class notation provides environmentally conscious shipowners with an opportunity to demonstrate a low environmental ‘footprint’, thereby adapting ships to future regulations and avoiding exclusion from sensitive areas.