Performance and impact on the seabed of an existing- and an experimental-otterboard: comparison between model testing and full-scale sea trials

A new otterboard door design (Clarck-Y door) was tested in both flume tanks and at sea to compare its possible impact on the seabed compared to an existing door (Cambered vee) design. The two doors had a similar behavior with regard to the attack angle and the magnitude of drag, lift and efficiency coefficients in the flume tank experiment. In the sea trials, the Cambered vee door had higher values for the drag and lift coefficients than the Clarck-Y door and the horizontal door spread was also higher in the Cambered vee compared to the Clarck-Y door. Based on the results of the flume tank experiment, the Cambered vee door had a larger attack angle on the seafloor than the Clarck-Y door. The sea trials suggested the towing force of the vessel greatly influenced the reaction force of the doors.