THE MOTIONS OF CONNECTED HULLS IN REGULAR HEAD SEAS

A hinged ship comprises a series of hulls connected end to end by horizontal hinges which allow it to deflect in the vertical plane only. In this analysis, the hinges are assumed frictionless; that is, they transmit vertical and horizontal force, but no bending moment in the vertical plane. Linked ships are also treated, the link being idealized as a connection which imposes no constraint on the vertical movement of adjacent hull ends and transmits only horizontal force from hull to hull. The theory developed is an extension of Korvin-Kroukovsky's linearized theory of the motions of a single hull in regular head seas. Solutions are obtained and numerical results are presented. The numerical results are not startling. The general effects of hinging are to make pitch greater and heave smaller, and to shift the maxima of both to longer wave lengths. Heave, pitch, and vertical hinge force all peak at about the same wave length. Dimensionless heave and pitch approach unity at higher wave lengths, while vertical force approaches zero. Horizontal force increases smoothly with wave length for an infinite string of hulls, while for a finite string it has an oscillatory component superimposed on the general increase.