Safety And Seakeeping

Vector Foil Proa

In this chapter we shall be primarily concerned with the problem of multihulPs extreme initial stability and the consequent high com-at sea. Other grave situations may occur, of course. Multihulls may be dismasted in situations where a monohull would not owing to the multihulls extreme initial stability and the consequent high com-pressional loading on the mast owing to gusts. Multihull rudders and boards are similarly more prone to breakage than monohull rudders as a result of the considerably...

Asymmetrical Racing Hulls Catamaran

Trimaran Central Beam

Represents a zero-order approximation for the wave resistance. This is not good enough for our purposes, however. An exact theory was given by Havelock in 1932. A simplified, but still quite general form of Havelock's equation has been found by Castles for hulls with lateral and longitudinal symmetry. A discussion of the physical basis of Havelock's theory and Castle's equations for single or multiple hulls is given in Appendix A. Castles' equation for a single hull is The quantity 5 is the...

The Physics Of Fast Sailing

Incat Catamaran Body Line

Sailing boats exploit the discontinuity in fluid flow that exists at the air water interface in order to propel themselves. We may consider the water to be at rest and describe the velocity of the wind by a vector VT. The magnitude of this vector is equal to the wind speed with respect to the water and the direction of the vector coincides with the wind direction. Under the influence of the wind, the boat moves at a speed VH in a direction given by the vector B. Motion of any object through...

Hydrofoil Applications

Hydrofoil Catamaran

The tendency to view hydrofoils only as a means to lift the hull or hulls clear of the sea is conditioned by the fact that hydrofoils have been applied mainly to engine-powered craft which are subject to a less complex set of forces than sailing craft. In Fig. 6-1, to obtain a quantitative feeling for the problem, we have plotted the vertical lift-to-drag ratio weight-to-resistance of a typical multihull craft as a function of VJ L using Eq. 1-8 . Also shown is a curve labelled hydrofoils,...