General HydroStatics
Ship Stability Software
Command of the Week
(New or interesting aspects of GHS that you may not know about)


In GHS parlance, a tank being Flooded is not equivalent to its being Damaged. When its type is set to FLOOD, the tank is damaged as severely as possible: it leaves a hole in the hull where seawater is free to enter and exit. "Damage Stability" calls for Flooded tanks because it cannot look at every possible sort of damage that might occur.

On the other hand we have the DAMAGED tank type where the flooding within the tank depends on a particular point, which might be interpreted as the point of damage. In order for seawater to get into the tank, that point must be immersed below the external waterplane. We use the tank's Reference Point to mark the point where that happens.

Most useful applications of the DAMAGED tank type are not in general stability, but rather in particular cases where the location of the opening into the tank is known. An example is the open cockpit.

An open cockpit can be modeled as a tank in the DAMAGED mode with its reference point set at the coaming where flooding takes place if the heel angle goes high enough. We can use GHS to make a righting-arm curve depicting that angle. Here is an example with a little bilge water included for effect:

A great deal more could be said about the DAMAGED tank type. Its versatility is due to the fact that it balances pressure at the reference point. But this is a holiday, and no one wants to think too hard on a holiday.

For those who don't care about that, the short run file that both created the geometry and produced the output shown above is here. Further on arranging for several points to represent the coaming edge see

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