The most important step in analysis of a damaged condition, is to calculate the equilibrium conditions, which include the final trim, heel and drafts after the location and extent of damage is known. There are two methods that are used for this purpose. We will only graze through the concepts of each.
• Lost Buoyancy Method:
This method assumes that the damaged compartment does not contribute to the total buoyancy of the ship. Hence, the ship loses a part of its total waterplane, and its buoyancy, therefore reducing stability. This method is easier to use, because it is not iterative. On the other hand, the results obtained from this method are slightly less accurate than the other method.
• Added Weight Method:
The added weight method considers the flooded water to be a weight added to a certain point in the ship. The problem is them solved like a traditional weight addition case, and the trim and drafts are calculated over a set of iterations. Though this process is time consuming, it provides more accurate results, and is hence used by most stability analysis software.