DESIGN OF AN INNOVATIVE PROPELLER SHAFT BRACKET FOR SAILBOAT

This paper presents the modelling of a propeller axis bracket for sailing ships of 24 m length, realised in advanced composite materials. Currently, the commercial brackets for sailboats are built in bronze, thanks to the good casting specifications of this material. Nevertheless, the high density leads to very high weights and a mass reduction can be advantageous, in order to raise the payload and lower the overall costs. Moreover, the use of composite materials for this application is proposed by authors [A] as a suitable way to improve aesthetic design, increase bracket structural strength and optimize the shape to lower hydrodynamic drag. A design optimisation has been carried out by means of a genetic algorithm, evaluating a fitness function representative of project constraints and requirements. The authors believe that the result obtained is valid: the propeller axis bracket herein modelled and optimised has been physically built in several models, and will be inserted on catalogue for the sale to the public in the next future. The final component, although more expensive than the bracket in bronze, presents a much less weight, a pleasant design and an increased structural resistance. Future developments will follow the certification by RINA (Italian civil naval authority) and the extension of the design methodology to other naval items in composite materials.