Directionality and Maneuvering Effects on Surface Ship Underwater Acoustic Signatures


  1. Trevorrow, M.V.
  2. Vasiliev, B.
  3. Vagle, S.
Corporate Authors
Defence R&D Canada - Atlantic, Dartmouth NS (CAN)
This work examines high-resolution measurements of surface ship source spectra using a set of four self-contained, freely-drifting acoustic buoys. A variety of straight-line and maneuvering runs were performed past these buoys with a small, single-screw oceanographic vessel. Each buoy continuously recorded two calibrated hydrophone channels with up to 20 kHz bandwidth, along with the buoy’s GPS position. The use of two hydrophone depths allowed assessment of surface-reflected interference effects, which were found to be minimal for this ship. Instrumental deficiencies limited the effective acoustic bandwidth to 100 Hz to 5 kHz. Measurement ranges were from 20 to 400 m. In straight, constant-speed runs the ship source spectra showed a peak near 150 Hz with spectral levels up to 158 dB (re 1 microPa^2/Hz at 1 m) at 11 knots, decreasing approximately as inverse frequency-squared up to 5 kHz, in general agreement with reference spectra. Source directionality patterns were extracted from variations in source spectra while the ship transited past the buoy field. The observed spectral source levels exhibited a broadside maximum, with bow and stern aspect reduced by approximately 10 to 15 dB, respectively. The broadband source level was observed to increase as approximately speed to the 4th power over the range 5 to 12 knots. Additionally, during turning maneuvers the ship exhibited simultaneous variations in aspect angle, speed, and turn rate. After correction for source direction

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ship noise, source directionality, ship maneuvers
Report Number
DRDC-ATLANTIC-SL-2008-010 — Scientific Literature
Date of publication
15 Aug 2008
Number of Pages
Reprinted from
Journal of Acoustical Society of America, vol 124, 2008, p 767-778
Electronic Document(PDF)

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