Seakeeper is able to display a rendered 3D view of the model and the wavy free surface. In the Perspective view, choose Display | Render.

The default value of the wave amplitude is set to either 2.5% of the vessel length or the maximum wave slope, whichever is the least. The wave amplitude is set in the Display | Render or Animate dialogs.

There are three options for the free surface: static (flat) and, once the analysis has been performed, regular and irregular wavy surfaces may be used.

With this method selected, no free surface elevation is calculated.

Static (flat) free surface

With this method selected, no free surface elevation is calculated, however when you select Animate from the Display menu, a simulation of a free roll decay test will be displayed. This simulates the roll motion of a vessel heeled over to a specified initial roll angle and then released. The initial heel angle is held for 5 seconds, then the vessel is released.

To conduct a roll decay simulation, follow these steps:

§   Make sure you have specified all Seakeeping input data correctly by working your way down the analysis menu

§   Solve Seakeeping Analysis from the analysis menu

§   Calculate Wave Surface from the analysis menu

§   Select Roll decay simulation in the dialog that appears

§   Specify the initial heel angle

§   Select Animate from the display menu

§   Click OK

Note:

Saving the roll decay as a text file and then importing into Excel may help you further analyse the Roll decay simulation data.

Roll decay simulation

Note:

Because the roll motion is considered uncoupled from the heave and pitch motions, no heave or pitch motions are generated.

With this method selected, a single frequency and amplitude regular wave pattern is calculated. The wave frequency is one of the discrete wave frequencies for which the motions have been solved. The wave amplitude (half wave height) may be either automatically calculated (LOA / 40 or limited by maximum wave slope for non-breaking waves:  for short wave lengths) or may be specified by the user.

Regular wave surface

The final option allows an irregular wave pattern to be calculated based on the selected wave spectrum. The irregular wave pattern is calculated by superimposing linear regular sine-wave components. The number of wave components to be used can be changed by the user. The wave components are chosen so that the wave energy in each frequency is the same; each component is then given a random phase. If you have a slower computer, it may be necessary to reduce the number of wave components used; increasing the number of wave components will increase the detail with which the wavy surface and vessel motions are calculated.

Irregular wave surface

Once the wavy surface has been calculated it may be displayed. A grid representing the wavy surface may be turned on by selecting the Wave Surface option in the Display | Visibility dialog:

Note

The wavy surface grid uses the Net colour as defined in the View | Colour dialog.

The wavy surface may also be displayed by turning on the rendering (Display | Render).

In either display mode, the wavy surface grid may be turned on or off in the Display | Visibility dialog (as described above) or by using the Wave Grid button in the Contours toolbar: .