Creation of Overall Loading Condition Information

You enter the overall Loading Conditions environment by selecting the Loading Conditions icon, to which the Lightweight icon is subservient. At this level you can establish some general information that is relevant to many deadweight loading aspects, such as compartment/tank contents categories, for example, cargo, water ballast, fuel oil, , permeabilities according to compartment and contents categories, contents density values, grain angles, Additionally, at this level, you can also define the maximum permissible still water overall hull girder vertical bending moments, both hogging and sagging, and shear force distributions, as may be obtained from classification society rule requirement calculations that are outside the scope of Calc.

1. Creation of Compartment Categories.

   It is often very useful to be able to group compartments into separate categories. For instance, in the stability report, you may wish to list all ballast tanks together. It should be noted that these categories do not have to reflect the current contents of a compartment. For instance, a water ballast tank could be given the category "water ballast" (typically inferring salt water), but may contain fresh water in a particular loading condition. Before a compartment can be assigned a category, you have to create a list of those categories required for the specific ship design.

2. Assignment of Categories and Damage Permeabilities.

   Once the compartment categories have been created, as described above, you are then able to assign a category and a damage permeability to each compartment. The purpose of the damage permeability is to restrict the weight of flood water entering a compartment and is analogous to a reduction in the density of the flood water. The damage permeabilities entered from the resulting dialog are only used in the damage stability and longitudinal strength assessments of loading conditions and deterministic stability. They have no effect upon the amount of deadweight which can be loaded into a compartment. Furthermore, the permeabilities required for floodable length and probabilistic stability assessments are defined on their respective dialogs.

3. Creation of Compartment Content Types.

   Whereas the category of a compartment determines in which group it will appear in a report, the "content type" determines its actual contents in a particular loading condition. For instance, as stated above, a water ballast tank may contain fresh water in a particular loading condition and should therefore be assigned the content type "Fresh Water". Before a compartment can be assigned a content type, you have to create a list of those content types (regardless of compartment) required for the design. When each content type is created, you have to give it a value of density and specify whether it is liquid, solid or grain. The surface of a liquid is assumed to remain horizontal as the vessel heels, whereas the surface of a solid, is assumed to remain in the same Z-plane of the ship. For grain, you have to supply the grain inclination, which is the maximum angle the grain surface makes to the horizontal, when the vessel is in the upright position after shifting. From this, the grain heeling moment can be determined for the upright vessel. As the vessel heels, the grain heeling moment is assumed to decrease linearly at the rate of 0.5% per degree heel.