DEPLOYMENT OF CABLED, INLINE SENSORS, 3.5 TONS IN WEIGHT BY GEOFF BALL
INTRODUCTION
SYSTEM DESCRIPTION
From March 2000 to August 2004, Nautronix MariPro has installed four mid ocean sensor systems. These installations have many aspects similar to a traditional telecom cable installation. However, deployment of the 3.5-ton sensor assemblies as in-line cable bodies is far from traditional.
The end requirement is for three hydrophones in the SOFAR channel about 2 km apart from each other in an equilateral triangle. In order to connect the sensors, or nodes, to each other and the shore, the nodes are essentially deployed as in-line cable bodies. The floats and hydrophones are placed into the SOFAR by releasing them from the node assembly after the system has been installed. The result is that the hydrophones are bottom tethered and buoyed with syntactic foam floats. Each node weighs 3.5 tons in order to accommodate the anchor mechanics, electronics housing, riser cable, hydrophone and float. A deployed single node is shown in Figure 2.
The systems are part of a worldwide monitoring program for a proprietary customer. The systems contain hydrophones placed in the Sound Fixing and Ranging (SOFAR) channel that record information on low frequency noise sources. To date, installations have been completed in the British Indian Ocean Territory, off the coast of South Western Australia, off the coast of Chile and in the South Atlantic Ocean. Figure 1 is a representation of a deployed system.
FIGURE 1 TYPICAL DEPLOYED SYSTEM CONFIGURATION FIGURE 2 TYPICAL DEPLOYED NODE