Side-Scan Sonars Provide Another Tool For Search And Rescue Teams

By land, by air or by water, search and rescue teams are asked to perform their duties in a variety of environments. With temperatures rising across the state and with lakes and rivers becoming increasingly crowded as summer approaches, the California Governor’s Office of Emergency Services (Cal OES) Law Enforcement Division conducted an emergency response boating class this week on Big Bear Lake, which is situated in the San Bernardino Mountains and surrounded by the San Bernardino National Forest in Southern California.

The course, referred to as Side-Scan Sonar Operation and Interpretation, is designed to use a side-scan sonar to search for objects underwater and provide an introduction to the different types of usable sonars, as well as how sonar images are created and how to conduct a search.

A side-scan sonar is generally used to conduct surveys for marine archaeology and to create images of large areas of the sea floor. For search and rescue teams, the scans are used primarily to search for drowning victims as well as missing objects underwater.

“They are provided with the basic information and how to read the side-scan sonar,” said John Sutton, Law Enforcement Region III Assistant Chief with Cal OES. “There’s a lot of technique in reading side-scan sonars and what’s needed in the type of training.”

US&R boat2

Eleven counties – San Bernardino County Sheriff, Placer County Sheriff, Ventura County Sheriff, Tulare County Sheriff, Santa Barbara County Sheriff, Mohave County Sheriff, Los Angeles Port Police, Del Norte County Sheriff, Solano County Sheriff, Merced County Sheriff and Tuolumne County Sheriff – participated in the three-day course, which began with a focus solely on classroom discussion on the first day. On-the-water search and practice placing marker at victim/object for guiding recovery consumed day two, and the third day consisted of more on-the-water searches and a de-briefing.

Also joining Sutton from Cal OES were Assistant Chiefs Sherri Sarro, who represents Region VI in parts of Southern California, and Greg Smith of Region II in the Bay Area.

The class size was limited to a maximum of 50 students and eight boats. Aside from searching for underwater objects, some of the course objectives included: Orient students to the range of sonar equipment; methods and selection of the best tools to use; provide students the opportunity to review and interpret sonar images; and discuss pre-search planning and importance of reliable witness interviews, weather data and real-time navigation programs.

Typically, the side-scan sonar searches a swath 60 to 160 feet wide at about 2 miles per hour, although other ranges can be used depending upon the size of the object being sought, according to Gene Ralston, who teamed with his wife Sandy to conduct the search and rescue course.

The Ralstons, based out of Idaho, have performed 103 recoveries throughout their 20-year career, according to Sutton. The reason for training other departments is to not only limit the Ralstons’ travel schedule but also to ensure more successful findings in the future.

“From the start of the course to the end of the three days it’s a considerable gain for these departments,” said Sutton. “They’ve had the equipment in boxes for years and haven’t pulled it out and don’t know the capabilities, and now they’ve had a chance to learn the nuances of it.”

Jonathan Gudel

Jonathan Gudel is a Public Information Officer for the California Governor's Office of Emergency Services (Cal OES). Since joining Cal OES, he has assisted in the response and recovery efforts of the Aliso Canyon Gas Leak, the state's historic drought, the Oroville Dam Emergency Spillway Incident, unprecedented winter storms in 2017, the 2017 October (Sonoma County) and December (Santa Barbara County) wildfires, the Camp Fire in 2018, the 2020 statewide fire siege, and the COVID-19 pandemic. Previously, he worked in the newspaper industry for 12 years.

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