An innovative force sensor to evaluate the drag of small outboard motor watercrafts

Drag coefficients are important parameters in modelling the dynamic behavior of watercrafts and in design efficient and reliable control schemes for them. Evaluation of drag coefficients, either by theoretical or by experimental methods is a challenging and resource demanding problem. In this paper, we describe an innovative sensor that can measure the thrust of the outboard motor which propels a watercraft. In steady state motion, the measured thrust equals the drag and therefore its measurements can be used to determine drag coefficients. The structure and the characteristics of a prototypal version of the sensor are described, together with its calibration procedure. Field tests are illustrated and the results of measurements are discussed. Copyright © 2017 by the International Society of Offshore and Polar Engineers (ISOPE).