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The time-dependent spectral characteristics of underwater sound radiated by an ocean vessel has complex dependencies on ship machinery, propeller dynamics, hydrodynamics of ship exhaust and motion, as well as ship board activities. Here the underwater sound radiated by a ship equipped with a controllable pitch propeller (CPP) is analyzed and quantified via its (i) power spectral density for signal energetics, (ii) temporal coherence for machinery tonal sound, and (iii) spectral coherence for propeller amplitude-modulated cavitation noise. Frequency-modulated (FM) tonal signals are also characterized in terms of their frequency variations. These characteristics are compared for different propeller pitch ratios ranging from 20% to 82% at fixed propeller revolutions per minute (RPM). The efficacy and robustness of ship parameter estimation at different pitches are discussed. Finally, analysis of one special measurement is provided, when ship changes speed, propeller pitch and RPM over the duration of the measurement. The 50% pitch is found to be a crucial point for this ship about which tonal characteristics of its underwater radiated sound attain their peak values, while broadband sound and associated spectral coherences are at a minimum. The findings here elucidate the effects of pitch variation on underwater sound radiated by ships with controllable pitch propellers and has applications in ship design and underwater noise mitigation.
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This content will become publicly available on January 1, 2026
Underwater Acoustics for All: Expanding Capacity with Education and Low-Cost Sensors
Sound is a persistent yet dynamic component of the marine environment, reflecting both physical and biological properties. Whereas light can only travel tens of meters in the ocean, sound is able to travel tens to thousands of kilometers under certain conditions, revealing information at specific times and places. In addition, underwater sound provides opportunities for sustainable development and blue economy growth that aren’t readily available with other technologies. For example, the melting rate of Arctic ice and the health of coral reefs can be estimated from acoustic measurements (Becker et al., 2023). However, underwater acoustics is a complex topic, requiring specialized education and equipment. To expand the capacity of underwater acousticians requires dedicated educational opportunities and low-cost equipment and analysis resources.
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- Award ID(s):
- 2318309
- PAR ID:
- 10599694
- Publisher / Repository:
- The Oceanography Society
- Date Published:
- Journal Name:
- Oceanography
- ISSN:
- 1042-8275
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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