Damage Scenario Dialog - Other Data Tab

Damage Scenario Dialog - Other Data Tab.

Waterplane Data

The Waterplane data section of the dialog controls how the waterplane is to be treated for this damage scenario. Three types are available from the drop down list, Free, Free (+start) and Grounded.

If the Free option is selected you need not enter any data except a value of TCG Shift, if required (units: metres or feet). The Free option uses the intact equilibrium as a starting point for the iteration process. A positive value of TCG Shift always increases the angle of equilibrium, by applying an alteration of TCG Shift*cosθ to the GZ curve. This adjusted GZ curve is then used in any critical KG/GM calculations. It should be noted though, that the hydrostatics are reported at the equilibrium angle prior to the TCG Shift.

The Free (+start) option only differs from the Free option by allowing you to specify the waterplane at which to start the iteration process. The starting waterplane is defined by the Mean Draft (units: metres or feet), Trim BP (units: metres or feet), and Heel (units: degrees) entered. As with the Free option, a value of TCG Shift may be entered if required. See above for explanation.

Selecting the Grounded option allows you to specify the final waterline following grounding. The final waterplane is defined by the Mean Draft (units: metres or feet), Trim BP (units: metres or feet), and Heel (units: degrees) entered. No TCG shift may be entered.

Single Point Grounding

The grounding point relative to the ship's co-ordinate system is specified on the Damage Scenarios/Other Data page together with the height of water above the point. The grounding force is included in the longitudinal strength, as well as the stability, calculations. If the grounding force becomes negative (i.e. the ship floats off the grounding point), then a normal, ungrounded condition is assumed.

Water on Deck

This section is used to specify the extent of damage. Two options are available, Calc from X vals and Explicit XYZ. Using the first option, you only needs to enter the X value at the two points (defining the extent of damage). The program measures the height from the deck (found from the geometry model at the x coordinates for the specified compartment(s)) down to the waterline.

For the Explicit XYZ option, the program simply measures the distance from the specified points down to the waterline.

In either case, the point which gives the smaller freeboard not only defines the freeboard but also becomes the point at which the height of accumulated water is applied. The X, Y and Z values are measured relative to the vessel's origin (units: metres or feet).

Required Parameters

Damage Zones

For Probabilistic Stability, a damage scenario must be associated with one or more zones. This is done automatically when the automatic generation facility, is used. If you adds or changes damage scenarios, then he or she must ensure that they are properly associated with the correct zones.

Stage Flooding

This section is for setting the number of stages and default percentage filling, for stage flooded compartments. This should be done, before stage flooded compartments are selected on the main dialog.