Advanced computing algorithms also make it possible to accurately differentiate divers from seals and other animals. Sonar enables users to spot and track divers or submersibles to calculate their speed before dispatching a diver interception team. And the technology's enhanced portability enables users to move these units around as needed, e.g., for times when high-value targets such as naval fleets or cruise ships enter a harbor.Diver safety and productivity
Ultimately, the foundation of underwater security rests with dive team members who must submerge in order to enforce the law and maintain security. These divers face extreme risks as part of their regular duties, such as freezing turbulent water with poor or zero visibility.
Divers sometimes perform this work on their own time to conduct criminal investigations; locate contraband, bodies, boats or planes; or map out underwater crime scenes. In murky waters, divers regularly have to reach out and feel around by hand, when there could be razor-sharp glass or sheet metal inches from their faces or blocking their way. Often they have absolutely no idea where those hazards may lurk.
"The safety of police dive teams is the top priority, but dives often occur in murky or turbulent waters where you can't see even your hand in front of you," says Sgt. Jeff Morgan, commander of San Bernardino's dive team. "Advanced sonar technologies enable the dive operation manager to know exactly what is down there, pinpoint its location for a quick recovery, and make the dive much more efficient and safe for the divers."
Sonar equipment becomes the "eyes" down below as observers on the surface monitor sonar screens in real time to tell divers the exact positions of targeted objects and hazards. From a risk-management viewpoint, this technology's ability to safeguard divers while they're working underwater may be its most valuable use to law enforcement.
Making the best use of the limited time divers may remain underwater becomes another critical benefit. Instead of fumbling around a seabed crime scene as if blindfolded in a darkened room, sonar technology pinpoints exactly where divers should go. In a body recovery situation, for instance, surface observers can send divers directly to the right spot, while steering them around hazards that lie in their path.
For example, Big Bear Lake outside San Bernardino often presents zero visibility for divers. But when a private plane crashed into the lake in front of eye witnesses on June 23, Morgan and his divers knew exactly where to look. Or, so they thought. "We had a number of witnesses, including a deputy sheriff, who carefully marked his location and where he saw the plane enter the lake," Morgan says. "Unfortunately, the plane's forward momentum carried it 80 yards away from the point of entry. Given that we only had about 6 inches of visibility, it might have taken us days to find the wreckage."
But with a sonar system, they were able to spot the plane and bring it up within three hours. "The sonar unit saved us countless hours," says Morgan. "Once we located it, we were able to drop a line down to it and send a diver down to check for fuel leakage and put on the lift bags. What would have been a long expensive operation was completed within a few hours."
There is often a large amount of evidence to recover in an underwater crime scene. In these cases, sonar can be utilized to first map out then take a picture of the scene, providing a detailed record. Law enforcers can use this image to develop a productive recovery program.
"Our investment in this technology has paid for itself many times over in reducing overtime costs alone," concludes Morgan, a national expert who helped pioneer the use of sonar technologies in body and evidence recovery.
San Bernardino's dive team has a long history in successfully using sonar. Divers first discovered its value five years ago when they were unable to locate the body of an 18-year-old jet skier in the lake. A month later, after getting their first sonar unit, divers discovered the body as they searched for a boat that had crashed and sunk into the lake.