Underwater cat's eyes uses sonar to locate objects

Using a nautical version of “cat’s eyes”, defence scientists have developed a more environmentally sound method of marking underwater locations and/or high value assets, such as oil fields or transatlantic cables.

Dstl scientist Carl Tiltman presented the new technology at the MOD’s Future Soldier Event, part of the National Science and Engineering Week. The Min(DES) Baroness Taylor is seen with the Dstl scientist who is holding one of the “bowling ball” sized reflectors. The event was covered by the BBC and the Guardian.

To date, battery-powered sonar location devices have been used by oil companies and cable companies to send a pulse back from where objects are located on the seabed. Unfortunately, the batteries need periodical replacement and result in significant ongoing maintenance costs. If the batteries are wholly exhausted the devices themselves can become “lost”. However, scientists from the Defence Science and Technology Laboratory (Dstl) have successfully shown that a spherical shell device can reflect back the sound from existing sonar systems. This creates a similar effect to that of shining a car headlight onto a cat’s eye on the road.

Historically, passive devices have relied on toxic chlorofluorocarbons (CFCs) housed in metal disks to bounce the sound back.  The new environmentally friendly system has no requirement for CFCs as the physical properties of the cat’s eye is powerful enough to send a decent “wave of sound” back to the sonar.

Subsea Asset Location Technologies Ltd, has been setup specifically to commercialise this exciting development in underwater asset management. Dstl scientist John Smith said the exciting new technology had progressed beyond the initial prototype stage, John said:  “A passive device which reflects back the sound from existing “off the shelf” sonars is inexpensive and non-toxic and has the advantage of not contributing to the background noise pollution which is becoming an increasing problem in the ocean.”

Commercial development of the technology has been led and funded by Dstl’s technology commercialisation company, Ploughshare Innovations Ltd. Subsea Asset Location Technologies has begun fundraising to complete the prototyping phase and deliver the product to market.

David Harris, Dstl’s Head of Technology Transfer said “This is another example of Dstl technology being directed outside its original military application and making a difference to industry.”