Large angle stability lets you determine the hydrostatic parameters of the hull at a range of heel angles either with or without trim or free-to-trim.

Select Large Angle Stability from the Analysis menu or toolbar.

The following analysis settings apply for Large Angle Stability Analysis:

§   Displacement and Centre of Gravity using the Loadcase window

§   Heel from the Analysis menu, select range for analysis

§   Trim (fixed or free) from the Analysis menu

If criteria are being evaluated, the heel range and heel angle steps should be chosen accordingly, to ensure accurate evaluation of the criteria.

Note

You can select positive heel direction (port or starboard). However, you can enter negative values and test full 360 degrees of stability if you wish. Some criteria require calculations of GZ at negative heel. The criteria are only evaluated on the side of the graph that corresponds to positive heel angles.

For example: when using a -180 to 180 heel range, the results may be two angles of vanishing stability, the one that would be reported in the criteria would be the one with a positive heel angle (even if the one at negative heel occurred at an angle closer to zero).

Also see: Heel on page 94 in the Analysis Settings section.

The following environments can be applied to the large angle stability analysis:

§   Fluid simulation of tank fluids centre of gravity

§   Density

§   Wave Form (if any)

§   Hog and sag (if any)

§   Damage (or Intact) from the Analysis toolbar

§   Stability Criteria

Large Angle Stability Analysis results are:

§   Hydrostatic data table for each angle of heel

§   GZ curve

§   Stability Criteria evaluation

§   Downflooding angles to key points, deck edge and margin line

§   Curve of areas at each heel angle

Stability Criteria Evaluation

The criteria results are displayed in the Criteria tab in the results window. For more information on how to customize the display of the criteria results, please refer to the Results Window on page 138 in the reference section.

Important:

For important information on varying displacement while evaluating criteria, see: Important note: heeling arm criteria dependent on displacement on page 183.

Downflooding Angle

After a Large Angle Stability analysis, the Key Points Data table lists the downflooding angles of the margin line, deck edge and defined Key Points. In addition, the first downflooding point is marked on the large angle stability graph. Only the positive downflooding angles are displayed, hence if there is any asymmetry, the large angle stability analysis should be carried out heeling both to starboard and to port. For the margin line and deck edge the longitudinal position at which immersion first occurred is provided.

Downflooding points that are linked to tanks or compartments that are damaged in the currently selected damage case, will be ignored when computing the downflooding angle. These downflooding points will appear italicised, and an asterisk (*) is postfixed to the downflooding point’s name in the Key Point Data table of the Results window.

A downflooding angle of zero degrees indicates that the key point is immersed at zero degrees of heel.

Also see:

       Select View from Analysis Data on page 110.