what is basic difference between intact stability & damaged stability?

Intact stability and damaged stability are two different concepts related to the stability of a ship or a floating vessel. Here's a brief explanation of each:

Intact Stability: Intact stability refers to the stability of a vessel in its undamaged condition, typically when it is upright and floating freely in calm water. It deals with the vessel's ability to resist capsizing or rolling excessively due to external forces such as waves, wind, or changes in weight distribution within the ship. Intact stability calculations take into account factors like the vessel's geometry, center of gravity, buoyancy, and moments of inertia.

Damaged Stability: Damaged stability, on the other hand, focuses on the vessel's stability after it has sustained damage or flooding. It assesses the ability of the ship to remain afloat and maintain stability even with compartments flooded or structural damage. Damaged stability calculations are crucial for evaluating a vessel's survivability and ensuring it can withstand damage scenarios such as hull breaches, compartment flooding, or equipment failures. These calculations consider factors like the extent and location of damage, free surface effects (water movement within the vessel), and the redistribution of weight and buoyancy due to the damage.

Intact stability deals with the ship's stability in normal operating conditions, while damaged stability evaluates its stability and ability to stay afloat after sustaining damage or flooding. Both aspects are important in ensuring the safety and seaworthiness of a vessel.