A microprocessor-based data logger and an instrument-mounting platform used in shelf sediment-transport and boundary-layer research are described. The data logger is based on a master-slave concept and can support, in principle, any number of sensors, which all operate on the same real-time base. Considerable flexibility in experimental design results, which enables the optimum use of data-storage capacity and power supplies, as well as the implementation of complex sampling schemes. The instrument-mounting platform provides the physical support for current meters and optical and acoustic devices for measuring suspended-sediment concentration. The guiding design principle has been that the structure should disturb the flow only in ways that do not compromise the application of typical methods of data analysis.