Vibration analysis for the comfort assessment of a superyacht under hydrodynamic loads due to mechanical propulsion

Yacht designers and builders are continuously looking for new solutions to reduce construction costs and to improve the quality and innovation of their vessels. In the case of superyachts over 30 m in length, performances are no longer a primary goal and the efforts of technical offices are mostly addressed on other aspects related to the aesthetic impact of the project and to the on board comfort. From this point of view, vibrations and noise represent a difficult issues to deal with for designers, both in the initial phase of the project, when it is necessary to have preliminary information about the response of the structure not yet defined, and during construction, in case some critical behaviors arose in any part of the structure. In this paper, the dynamic behavior of a 40 m motor yacht is investigated. The Vibration Velocity Spectra obtained by the numerical model of the yacht are compared with the value of level limits imposed by the ISO6954:1984. Different structural solutions are investigate to improve the comfort level in same area not in compliance with the rule.