Seakeeping Dialog - Hydrodynamics Tab

The following information is required to calculate and view the results of the Hydrodynamics calculations.

Calculation Method

Two methods are available for the computation for the hydrodynamic coefficients:

• Lewis, References 41, 42, 43 and 44

• Close Fit, References 36

If Close Fit is chosen, then you must specify the number of points into which each section is girthed. By default a value of 8 is supplied. This should be adequate for most hull types. However, sections with high areas of curvature may require a greater number of points to accurately model the section. A maximum of 20 points is allowed.

Graphics

Two graphical representations are available to help you to decide on the applicability of the Hydrodynamics method chosen.

• Body Sections

• Lewis Valid Region

If the body sections are plotted, then the following may also be superimposed onto the diagram:

• Lewis Sections

• Close Fit Points

By viewing the Lewis Sections, together with the Lewis Valid region plot, you can ascertain whether any of the vessel sections fall outside the valid region for Lewis sections.

By displaying the Close Fit points, you may decide that more or less points are applicable, for example, if certain sections have areas of high curvature, then more points may be required to model the sections accurately.

Sections

Up to 50 sections may be defined along the vessel. These sections are automatically produced by making slices through the model. These sections are used to generate the 2D added mass and damping coefficients, and hence by integration, the total hydrodynamic coefficients for the vessel.