The development of a near bed recording system

An instrumented tetrapod for recording water velocity and other parameters near the sea bed is discussed. It has been developed from a shallow-water system with a life of weeks. Sensors used include electromagnetic current meters, transmissometers, a pressure transducer, acoustic backscatter probes, miniature optical backscatter units, roll and pitch potentiometers, a temperature thermistor, a water sampling device, an acoustic altimeter, and a still camera and flash. The sensors are discussed. A redesigned system is described. Launch and recovery technique, as well as data handling, are discussed