The fundamental fact about manoeuvring of geometrically similar ships, of
whatever length (or size) and initial steady approach speed, including scale physical
models and the whole series of full-scale ships (if they really exist), is that the
nondimensional track (in ship length units), the drift angle and the nondimensional
yaw velocity are maintained. The only difference is the allocation of time moments
to subsequent ship positions and/or heading. The higher is the speed and the
shorter is the hull length, the time 'runs' faster. The present paper deals with a methodical
explanation of these phenomena in view of building the manoeuvring
model for a virtual ship of arbitrary size. Problems with satisfying the similarity of
propeller parameters, the occurrence of scale effect in the resistance coefficient,
and the consequences of variation in the ratios of main dimensions are analysed
against the increasing ship length.
