Seeking efficiency improvements for a motor-yacht transitional hull form

Abstract

Experience in developing and refining custom high-performance race yachts unrestricted by rules has created an innovative approach to evaluating design challenges and considering potential solutions. This methodology has been applied to developing an efficient motor-yacht hull form with the potential for increased efficiency when operating in the transitional zone between displacement and planing speeds.

This paper looks at the challenges to efficiency posed by increasing performance of a 50 metre super yacht beyond displacement speed and into the high-resistance transitional speed range. A review of existing solutions to this problem are considered, including various hull forms, use of foils and developments in multihull design. It also proposes a concept hull design, influenced conceptually by some fast displacement multihulls, which offers a solution to improved efficiency in the transitional zone.

The concept hull is developed and compared to more conventional monohull displacement and planing hull forms. Particular attention is focused on the performance in the transitional speed zone. Factors influencing performance such as appendage drag, displacement-length ratio and power-to-weight ratio are considered. Further consideration is also given to other characteristics influenced by this design concept such as safety, comfort, maintenance and directional and static stability.