Clear as a bell despite local interference
SonarBell technology is easily deployed and needs no maintenance.
The demonstration of a novel undersea marking device went well despite the best attempts of the local sailors.
Subsea Asset Location Technologies Ltd (SALT) was showing off its SonarBell technology at ABP Southampton recently when on the first day a power boat shaved very close to the demo vessel Protector and on the second day a yacht managed to foul the demonstration’s mooring line.
Despite all of this, ABP’s Reson SeaBat 8101 multi-beam sonar system easily detected and indentified the array of SonarBells, which had been pre-deployed on the seabed.
The audience came from many sectors, marine survey companies, government marine related agencies, engineering and environmental consultants, archaeologists and marine equipment manufacturers and suppliers. This alone should please SALT, a military and defence company spin-off that thought its research could be put to wider use.
SonarBell is an inert, stable and totally passive device for marking and locating any asset on the seabed or in the water column. It is omni-directional, requires no maintenance, ranges in size from 50mm to 200mm and is visible for up to 2km, depending on the frequency and power of the sonar.
Although SonarBells are easily put down in depths of water up to 300m to mark assets that need to be monitored, repaired or recovered, they do go well beyond their designated application limits. For example, although the units are currently certified to 100m, they have recently been tested down to 4,100m and despite the 2km nominal limit to the system, bespoke units can be designed for further reach and deeper deployment.
The technology is innovative, easy to use and is less expensive to purchase and deploy than traditional battery powered and active transponder systems. Such powered transponders are not only expensive but require regular routine maintenance depending on use and battery life, limiting their applicability. In contrast, SonarBell is a passive reflector which acts much as a ‘cats-eye’ does in the road, by taking in external energy and providing a strong reflection in return.
Looking something like a bowling ball, the two materials of its shell and core create a constructive interference which delivers a return signal significantly above what might be expected from a hard reflecting sphere.
The demonstration days started with an overview and an outline presentation on the SonarBell technology and its capabilities, followed by the somewhat ‘harassed’ practical demonstrations in Southampton Water on the ABP survey vessel Protector.
Back in the classroom, each day finished with a demonstration of how, by using the system’s unique labelling, sonar reflections from individual SonarBell units can be transferred onto GIS for visualisation and as markers within a comprehensive asset management system.
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