3. EMPIRICAL FORMULAE OF HYDRODYNAMIC COEFFICIENTS
Most commercial ships built in modern times have been changed into stern bulb type. The stern hull profile of stern bulb type is shown in Fig. 2 and the rudder used in this study is conventional rudder(semi-balanced rudder).
Fig.2 Profile of Stern Hull Form
In Fig.3 〜 Fig. 6, the comparisons of linear hydrodynamic coefficients between PMM test results and predictions results using Inoue's formulae are presented according to d/L.
These Figures show that there are large differences between PMM tests and Inoue's predictions. This means that empirical formulae based on the old hull forms are needed the improvement for application for modern hull forms. From the comparison of linear hydrodynamic coefficients, in view point of dynamic lever, it can be observed that modern hull forms have poorer course keeping ability in full load conditions.
Fig.3 The Comparison of Y'v
Fig.4 The Comparison of Y'v-m'
Fig.5 The Comparison of N'v