How Underwater Noise is Evaluated in Waterjet Propulsion Development

Reducing underwater radiated noise is a key consideration in the development of Marine Jet Power’s waterjet systems. Noise levels are evaluated through design, testing, and validation as part of overall system performance. This approach supports silent and low-vibration operations across a range of marine applications.

Underwater radiated noise is influenced by propulsion system design, including hydrodynamic behavior and operating conditions. In waterjet systems, factors such as flow characteristics and cavitation contribute to overall vessel noise, making this an important parameter in the development process.

Research shows that propulsion systems are a contributor to underwater radiated noise in vessels, highlighting the importance of addressing these effects early in the design phase.

A study published in Ocean Engineering demonstrates that propulsion system selection, system design and operating conditions significantly influence underwater radiated noise, particularly through hydrodynamic effects such as cavitation and transmitted vibration from power generators. The findings highlight the importance of evaluating noise characteristics early in the design process.

Therefore the use waterjet propulsion systems have increased significantly, as they generate lower noise and exhibit superior anti-cavitation performance compared to conventional propeller systems. But also, in waterjet systems noise is generated and transmitted and system design considerations will impact noise performance.

Evaluation through Testing and Analysis
The R&D team at Marine Jet Power evaluates underwater noise as part of product development and validation. Design choices and system configurations are assessed to understand how noise characteristics vary under different operating conditions.

Marine Jet Power waterjet systems have been certified in accordance with the DNV Silent Class Notation (DNV Rules Pt.6 Ch.24). Depending on the specific operating conditions, these systems meet the requirements for either SILENT-R or SILENT-E:

• SILENT-R (Research): The most stringent requirement, designed for noise-sensitive operations such as seismic or biological research, where minimal acoustic interference is critical.
• SILENT-E (Environmental): Ensures controlled and restricted noise levels to minimize the environmental footprint, facilitating operations in ecologically sensitive marine areas.

These classifications indicate low levels of underwater radiated noise and reflect the outcome of design and testing processes.

Continuous Development
Underwater noise remains an ongoing area of evaluation in waterjet propulsion development. By combining engineering analysis with testing, Marine Jet Power continues to refine system performance in relation to noise characteristics across different applications.