Key points such as downflooding points and hatch openings can be defined in Hydromax using the Key Points window. The points may be displayed in the Design View window and will be displayed in different colours depending on whether or not they are immersed. Immersed key points will be displayed in the same colour as flooded tanks or compartments.

Key points may be placed asymmetrically, a positive offset is to starboard and a negative offset is to port. Vessels which have symmetrical key points on starboard and port sides must have both key points added to the table.

There are several types of Key Points:

§   Down Flooding points

§   Potential Down flooding points

§   Embarkation points

§   Immersion Points

Only downflooding points are used in determining the downflooding angle, which is used in criteria evaluation. The other types of points have their freeboard measured but are not used for the evaluation of the downflooding angle and are for information only.

To start adding downflooding points go to the Key Points table, select New Key Points from the File menu. You will be given a default point. To add additional key points to the table, choose Add from the Edit menu or press Ctrl+A. A new point will be inserted below the currently selected row in the table.

To delete a Key point, click anywhere in the row of the point to be deleted and select Delete. To delete more than one point at a time, click and drag over the rows you want deleted.

Select Delete from the Edit menu, and the selected rows will be deleted.

Key points are defined by entering a name, a longitudinal position, a transverse offset from the centreline, and a height. Click in any cell and enter the name or value you require. All points are entered relative to the zero point.

The type of Key Point may be selected from the combo-box in the Type column of the Down Flooding Points table in the Input window:

Downflooding points may be linked to tanks or compartments. Select the tank or compartment from the combo-box in the Linked to column of the Down Flooding Points table in the Input window:

Downflooding points that are linked to tanks or compartments, which 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 DF Angles table of the Results window:

The downflooding angles for each of the points are displayed in the results window. The downflooding angles are computed during a large angle stability analysis; the freeboards after an Equilibrium or Specified Condition analysis. Immersed points are highlighted in red in the Freeboard column. In addition to the Key Points results, immersion angles or freeboards (depending on the analysis) are also given for the margin line and deck edge. In the Name column the longitudinal position where immersion first takes place (or the lowest freeboard) is given.

Note:

Linking a downflooding point to a tank does not mean that Hydromax will consider a tank damaged when the downflooding point is submerged. This form of automatic flooding is not supported in Hydromax yet.