The Influence of Hydrodynamic Assumptions on Ship Maneuvering

We present a preliminary assessment on the influence of the hydrodynamic assumptions associated with ship motions, for vessels maneuvering in calm waters. Three approaches are considered: (a) Model 1 idealising the maneuvering of a ship in 3-dof as per Brix (1993); (b) Model 2 representing the 6-dof hybrid time domain unified seakeeping / maneuvering model of Matusiak (2017); and (c) Model 3 - idealising combined seakeeping and maneuvering nonlinear characteristics in 6-dof by the time domain Green function method of McTaggart (2005). Simulations of turning circle and zig-zag manoeuvers are assessed and compared against available data for two tankers (KVLCC2 & Esso Osaka) and a container ship (DTC). It is concluded that in calm waters simplified models with hydrodynamic derivatives from either RANSE CFD or model tests can be used. However, implementation of well-validated CFD hydrodynamic coefficients may be more economic for the development of practical engineering tools, such as rapid assessment tools accounting for evasiveness in ship crashworthiness.