Investigation of the Use of Drogues to Improve the Safety of Sailing Yachts and Life Rafts

摘要

Model tests were conducted to investigate the use of drogues to improve the safety of sailing yachts and life rafts. The tests investigated the hazard of capsize by a breaking wave. The boats were assumed to be in a survival type storm with all sail off and not being controlled by the crew. The models were built to a scale of 1 to 32 and were weighted to give the proper dynamic characteristics. Two methods of breaking wave simulation were used: (1) A horizontal jet of water discharged at the model; (2) A breaking wave formed by the wake of a towed boat. A mathematical model was prepared which first simulated the motion of the boat-drogue system in non-breaking waves and then simulated a breaking wave strike. The tests indicated that the hazard of breaking wave capsize could be greatly reduced by the use of a properly engineered drogue. However, a systematic investigation of the parameters affecting the boat/drogue system, i.e. loads on the boat and drogue, line elasticity, wind and wave forces, has yet to be undertaken. More study and testing is required before a specific design can be recommended. (Author)