The Flying Fox is a portable towing and positioning system with built-in electric motor and remote control. It moves remote-controlled over a span of rope transversely to the flow axis and pulls a measuring device – e.g. an ADCP boat – for cross-section measurement through the river, and positions the device exactly at the measuring point. No need for a fixed cable crane: The system is mobile thanks to the low weight of the vehicle and the control system and the use of a synthetic rope rather than a wire: Simply span the rope over the desired river section, hang on the vehicle and control the ride over the water by remote control. No construction or earthwork is required. The particularly large climbing angle of up to 45 degrees facilitates the set-up even at points where, for example, there is a height difference between the right and the left riverbank. A safety lock prevents the tow vehicle from separating from the rope. The Flying Fox is controlled via a robust weatherproof remote control with backlit LC display. The LCD shows transect speed, position as distance from the starting point on the rope, wireless signal strength, voltage and current draw while operating, battery voltage, and low battery alarm (visual and acoustic).