Non-linear hydrodynamic hull forces derived from segmented model tests

In many situations the manoeuvering performance ofships is largely effected by the non-linear contributions of the hydrodynamic reaction forces on the hull. The origin of these non-linear components can be ascertained from experiments with segmented models.
In this paper a review is given of the analysis of the segmented model tests which have been reported in literature so far.
From the results derived from this analysis it will be shown that the non-linear hull force and moment components can be described in a robust manner by means of a longitudinal distribution of the so-called cross-flow drag coefficient. Thus, a good description of the ship's manoeuvrability is acquired for the entire speed range of a vessel, including the transition from the manoeuvres at service speed with relatively small drift angles to the manoeuvres at reduced speed (harbour manoeuvering) with large drift angles.
The paper also discusses the linear hydrodynamic coefficients asa result of the segmented model tests. The values of these coefficients sometimes deviate significantly from the general accepted coefficients presented in literature which were derived from measurements of the overall hull forces and moments on the complete model.
In the paper also the validity of manoeuvres predicted with the resultant mathematical model will be discussed.