Sonars on navy, research and fishing vessels are often "blinded" by the presence of air bubbles in the sonar beam. To improve the sonar's performance, several authors propose adjusting the filter settings on the signal returned by the sonar, to filter out the disturbances originating from the presence of the air bubbles in de beam. In addition to changing the filter settings, the sonar's longitudinal location on the hull should also be evaluated. Changing the sonar's position on the hull could reduce the number of bubbles that reach the sonar beam and therefore reduce the disturbances of the sonars signal. However, changing the sonar's position in an excising ship is expensive and therefore, the sonar's position should be chosen carefully during ship design. In this paper, we discuss four experimental and one numerical method to evaluate the presence of air bubbles in the sonar beam. We found that the path of the air bubbles is most accurately shown by either model tests where dye is injected in the area of the breaking bow wave or by Rankine source calculations where the bubble paths are visualized by tracing particles following the orbital motion of the wave. Model tests are more appropriate to obtain the path of the bubbles in irregular waves, while Rankine source calculations are more appropriate to obtain the path in regular waves.

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