A pair of specialised 3D profiling sonars has been returned to duty on a bridge carrying the Coastal Highway down the United States eastern seaboard. The sonars were delivered two years ago and have now resumed their task of monitoring the development of a large hole that is being scoured in the estuary bed due to water turbulence created near the bridge supports and by the syphoning effect of the Atlantic Ocean. The two sonars were manufactured by Marine Electronics Ltd in Guernsey and have just been returned to duty following a routine maintenance overhaul.
The sonars are operated by the University of Delaware which is maintaining the estuary watch. The University commissioned the specialised sonars from Marine Electronics Ltd specifically so that the scouring of the riverbed can be monitored.
The scoured hole is now over 30 metres (100 ft) deep and it is not known how long it took to develop because the rate of erosion is difficult to predict without the necessary quantative data. The only option has been to monitor it using the 3D sonars as the four-lane highway serves as a vital artery that carries traffic north and south along the coast.
The sonars are 250 kHz derivatives of the successful and versatile 2001 model 3D profiling sonar manufactured by Marine Electronics Ltd, which is based on the island of Guernsey in the English Channel. The sonars are mounted on each of the bridge’s piers where the water is rarely deeper than 5 metres (16 ft). From these locations they can monitor the estuary for some 150 metres (500 ft). The acoustic data obtained by the sonars is fed to a computer and control box that are used for examining the findings and for controlling the rate at which the sonars scan the riverbed to suit different water conditions.
Marine Electronics Ltd is widely regarded as a leading manufacturer of advanced and specialised sonar systems. The company has 27-years of experience in the development of acoustic technology that can be used to overcome unique and unusual problems. The company is able to work closely with customers in the development of products to resolve difficult acoustic challenges and to meet specific marine or industrial applications. Products include sonars capable of following the movement of individual grains of sand in seabed surveys, others can observe the build-up of sludge in nuclear reactors, sewer pipes or oil storage tanks. The company has also developed the first 3D forward-looking sonar fitted to an oil tanker for which it is available to provide warnings of shallow water or obstructions ahead.
First published on http://guernsey.isle-news.com/ on 30/06/2010