This paper describes the development and application of a synthesis‐level multidisciplinary design and optimization (MDO) method for multihull ships. This method is unique in utilizing advanced multi‐objective optimization methods, neural network (NN)‐based response surface methods (RSM), and in its broad scope, integrating powering, stability, seakeeping, hullforms definition, structural weights, and cost and payload capacity into a single design tool. This MDO method is developed in the context of a multilevel hierarchy system approach where the results of the synthesis level optimization can be used for subsystem optimization and overall coordination of multilevel design system. NN‐based RSM for seakeeping and powering is developed and used in the optimization process. This RSM approach moves the computational cost of such performance evaluations out of the optimization cycle, substantially reduces the optimization cost, and allows for using results of physics‐based methods, such as advanced computational fluid dynamics, at the synthesis‐design level of design hierarchy. Details of these methods are delineated and multi‐objective optimization results are presented in the form of Pareto optimum solutions for multihull ship concepts such as trimaran sealift support ships and catamaran high‐speed connector ships.

Quasi-linear theory (QLT) introduces corrections to the Havelock integral and makes it possible to operate with realistic wave amplitudes and length into framework of linear theory. These corrections for wave amplitude and length are based on implicit employment of the model 2D problems for nonlinear waves of highest magnitude (Stokes waves). There is both description of algorithms and comparison with towing test results for diverse ships here. A substantially novel (and environmentally important) aspect of this paper is application of QLT to computation of ship wave resistance in shallow waters.

Partial cavitation can substantially reduce the ship total drag in a wide range of her speed. Vented partial cavitation manifested certain advantages in comparison with other drag reduction techniques. Its successful employment, however, requires both a special hull design and development of an active flow control system. Such a system will stabilize the cavity under perturbations of incoming flow in seas. The paper includes an analysis of achievements in drag reduction, description of design fundamentals of ships with cavitating hulls/elements, and suggestions on application of ship drag reduction by cavitation.

A numerical technique for high-speed trimaran resistance calculation is developed. The technique is based on the modified viscous-inviscid interaction concept and quasi-linear theory of wave resistance (Amromin et al 1984). The key element of this technique, which is called modified quasi-linear theory (MQLT), is an account of Froude number influence on the ship trim, transom drag, and wetted surface. This influence leads to appearance of a drag component that significantly depends on both Reynolds number and Froude number. This component has been traditionally included in residuary drag in the model test data. The presented preliminary numerical results were obtained with simplifications of the boundary layer theory that are acceptable for slender hulls. Calculated drag is in sufficient accordance with results of model tests. The MQLT computations of boundary layers are also compared with the Reynolds averaged Navier-Stokes (RANS) calculations(one-equation turbulence model by Spalart and Allmaras 1992) at model and ship scale Reynolds numbers. An analysis of the model-ship scale correlation factor for high-speed slender hulls with transom sterns and diverse mutual position of the trimaran hulls is done.

This paper describes the concept design of a high-speed trimaran roll-on/roll-off (RO/RO) designed for commercial cargo but readily convertible to military use. It is designed for a coastal express service, such as Port Canaveral, Florida, to Wilmington, Delaware, so the emphasis is on speed, simplicity, and reliability. All the RO/RO cargo is carried on the main deck, and there is room for a limited number of passengers to accompany their cargos.