A newly designed deep sea YOYO-profiler for long term moored deployment

Abstract Within the framework of the national funded project DOMEST a deep sea YOYO profiler is to be developed at the University of Bremen. The primary goal of this system is to take continuous CTD-measurements over a depth range of 500 m above the ocean bottom. The system is designed to withstand a maximum pressure of 400 bar and is supposed to take one profile each day within one year. The system is also well suited to accommodate additional sensors as for example current meters or fluorometers. The basic instrument carrier consists of a hydraulic propulsion unit and an electronic controller unit. The hydraulic system is built to produce a buoyancy change of up to 3 kg to enable the free profiling motion along a taut mooring line. The electronic unit contains a new PC-based microcontroller that is expected to have a superior performance compared to the well-known TATTLETALE systems. The development of a deep-sea version calls for a special design of the whole instrument of smallest achievable volume. Therefore we are going to test the applicability of new pressure housing materials as for example ceramics. The paper will present first results of in situ tests taken during a cruise in October 1998.