7.1 Introduction

Monohulls and catamarans, often equipped with foils, trim tabs, and/or interceptors that control the trim angle and minimize wave-induced motions, are nowadays the most established concepts for high-speed vessels. Interceptors are relatively new concepts and are illustrated in Figure 7.5. The vessels have transom sterns, that is, there is a flat part of the aft ship below the mean free surface that is perpendicular to the centerplane. Catamaran designs include the wave-piercing and semi-SWATH (small waterplane area twin hull)-style hulls. The length of high-speed catamarans used for passenger transportation in coastal water is typically 30 to 40 m. Both monohulls and catamarans longer than 100 m have been built. Trimarans and pentamarans are new types of multihull vessels that are considered. They consist of a long center hull with smaller outrigger hulls. The outrigger hulls are important for static heeling stability. The larger vessels are typically ro-pax ferries, which means they carry passengers and allow roll-on/roll-off payloads, most often cars.

Calm water resistance of semi-displacement vessels is dealt with in Chapters 2 and 4. This chapter concentrates on linear wave-induced motions and loads; however, added resistance in waves is also handled. Common statistical procedures for calculating short- and long-term responses based on linear results in regular waves are also shown. One important load aspect is slamming, which is relevant for all high-speed vessels. This is dealt with in detail in Chapter 8. Maneuvering is considered in Chapter 10.