45.1 INTRODUCTION

The vast majority of waterborne craft have a single hull, because this provides a simple solution to the problem of transporting a given payload across the water, and at a minimum cost. The conventional monohull solution to the transportation problem is usually a compromise, because, as with most engineering problems, there are many different requirements such as payload and stability as illustrated in Figure 45.1. Prior to about 1850, the principal requirement of a craft was to provide as much stowage space for payload as could be fitted into a given length and sail layout. The speed of the vessel was never an issue, and it is only since the introduction of mechanical propulsion and the socio-economically-driven development of international trade, that the concept of maximizing speed has become important. Today, greater speed can provide a commercial edge in getting the product to the market as well as suiting the modern rapid lifestyle. Greater speed might be achieved by greater installed propulsion power, but usually it is more efficiently obtained by the minimization of resistance.

Figure 45.1: The Drivers of Vessel Speed

Unfortunately, such a minimization of resistance affects the compromise engineering solution that so favors the simple monohull at lower speeds.

Analysis of the somewhat simplified relationship illustrated in Figure 45.1 shows that the hull form determines the resistance of the craft. As will be further examined in this Chapter, the principal hull characteristics that determine the resistance at a given high speed are the...