Side Scan Sonar

Side Scan Sonar (SSS)

Side Scan Sonar is the most common type of sonar currently in use by the PSD community. Side Scan Sonar produces images by using two transducers attached either to the hull of a ship (Hull mounted) or to a towed body (towed). These transducers transmit an acoustic signal 90 degrees relative to either the ship’s hull or towed body. The signals reflect off the bottom and return to the transducers, which in turn generate a sonar image. Side Scan Sonar requires a stable platform and forward movement to create an image; it also requires the platform, either hull-mounted or towed, to travel in straight lines to create an image free of distortion.

Side Scan Sonar image of a truck
Video of Side Scan Sonar image of a truck

Due to this fact, they can be of limited use in areas with navigational constraints. Side Scan Sonar is generally the system of choice when conducting large area searches. They range in cost from a few thousand dollars ($3,000) to several thousand ($60,000 and up) and come in a variety of shapes and sizes.

Hull mounted systems can be particularly useful in shallow water (less than 60 ft). However, they are susceptible to rough water, which can severely degrade their performance.

Recent years have seen the rise of small radio operated boats equipped with side-scan sonar. These small platforms are highly portable and ideal for rapid deployment in remote areas. Thye can operate with greater ease in areas of restricted navigation such as harbors and shallow water. However, due to their small size, they remain vulnerable to rough waters and can even be affected by slightly choppy waters.

Towed Side Scan Sonars allow for searching in deeper waters and provide an overall better sonar image. They can be of limited to no use in areas with underwater obstructions such as trees or shallow waters. Depending on the size of the towed body and tow cable length, you may require a boat with a winch to handle deployment and retrieval of the system.

Harbor wall scan using Side Scan Sonar
Video of Harbor wall scan using Side Scan Sonar (Courtesy of Tritech International)

Side Scan Sonar may also be deployed to provide images of submerged vertical structures, as seen in the video on the left. This method allows you to image structures for evidence of damage or attached objects with a high degree of resolution in a fraction of the time required by traditional diving methods.

You can find details on our side scan sonar training programs on our Sonar Training page.