Dynamic Performance of the National Technical University of Athens Double-chine Series Hull Forms in Random Waves

Abstract

A systematic series of double-chine, wide-transom hull forms with warped planing surface has been developed at the Laboratory for Ship & Marine Hydrodynamics (LSMH) of the National Technical University of Athens during the last two decades. The series are suitable for medium and large ships operating at high but preplaning speeds and consist of five hull forms. Two scaled models for each hull form have been constructed and tested in calm water and in waves. In this article, systematic experimental results in random waves are presented. More specifically, the parent hull form with L/B = 5.50 was tested in three-level keel displacements, whereas the two corner hull forms with L/B = 4.0 and 7.0 were tested at the central displacement. Thus, the effects of both the displacement and the L/B ratio on the seakeeping responses are investigated. All tests were performed at two speeds corresponding to Fn = 0.34 and 0.68 using the Bretschneider spectral model with nondimensional modal periods TP' = TP/v(L/g) = 2.0-5.0 at steps of 0.5 and model significant wave heights H1/3 in the 8- to 16-cm range to represent moderate waves. Assuming linearity, the results for heave, pitch, acceleration, and added resistance are divided by H1/3 (i.e., they refer to H1/3 equal to unity).