sonar image wood sailing ship webLocating a large steel shipwreck like the 460-ft. victory ship pictured left should be a piece of cake. Anyone who can turn on the machine should be able to see the wreck when towing the system properly in good weather.

side scan second sweepBut poor weather conditions with excessive towfish motion is one of the main causes of distorted sonar imagery. High sea states and pitching survey boats increase the towfish motion. Heavy seas, faster tow speeds, longer sonar ranges, high towfish altitude and the wrong aspect make the huge ship appear much smaller. Hard to believe the side scan image to the lower right is the same shipwreck. The experienced sonar operator understands the limitations of weather conditions and designs his or her survey/search plan accordingly.

Examine the side scan sonar image on the left. One would think there are a couple of pipelines lying on the bottom. Actually, these are ghost images we call second sweep returns. Identifying ghost returns, especially for homeland security folks working in crowded harbors, is a critical sonar interpretation skill.

Need a better understanding of how to enhance your sonar skills? Try our Second Edition Not in the Manual Guide® to Side Scan Sonar Image InterpretationOr sign up for our next scheduled training seminar.

These programs will provide techniques such as:

  • How to detect ghost images
  • Determine if targets are on the bottom
  • How to conduct surveys between piers and other obstructions


Side Scan Sonar Manufacturers & Sonar Data Acquisition/Processing Software


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