Stability conditions (watercraft)

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Stability conditions (watercraft) is the term used to describe the various standard loading configurations a Ship or Boat may be subjected to. They are recognized by regulatory authorities such as Lloyd's, American Bureau of Shipping (ABS) and SOLAS. The conditions describe the Displacement (fluid) or weight of the vessel.

They are normally broken into two classes : Intact and Damage

Intact : The vessel is in normal operational configuration. The hull is not breached in any compartment. The vessel will be expected to meet various stability criteria such as GMt, area under the Gz curve, range of stability, trim, etc. while subjected to sustained winds, passenger heeling, manouvering, lifting, etc.

Damage : Based on the Worst Operating Condition the vessel is analytically damaged by opening various combinations of watertight compartments to the sea. The vessel will be expected to meet various stability criteria such as freeboard, trim, list, GMt, etc.

Naval vessels must meet standards described in military standards (ex: MIL-STD, CFTO) while commercial vessels are regulated by the government of the flag they sail under and the governments of the ports they operate under.

[edit] Intact Conditions

Lightship : The vessel is complete and ready for service in every respect, including permanent ballast. All flooded spaces such as Sea Chests are considered but the vessel has no cargo, crew, provisions, ammunition or any other load item.

Light Operating or Light Displacement : Along with all the Lightship loads, the vessel has all systems charged meaning that all fresh water, cooling, lubricating, hydraulic and fuel service header tanks, piping and equipment systems are filled with their normal operating fluids. Crew and effects are at their normal values. Consumables (provisions, potable water and fuel) are at 10% full load. Ammunition and/or cargo is not included (0% of full load).

Full Load Departure or Full Displacement : Along with all the Lightship loads, the vessel has all systems charged meaning that all fresh water, cooling, lubricating, hydraulic and fuel service header tanks, piping and equipment systems are filled with their normal operating fluids. Crew and effects are at their normal values. Consumables (provisions, potable water and fuel) are at 100% capacity. Ammunition and/or cargo is at maximum capacity. The vessel is at its limiting draft or legal load line.

Standard Condition (Only for Military vessels) : Along with all the Lightship loads, the vessel has all systems charged meaning that all fresh water, cooling, lubricating, hydraulic and fuel service header tanks, piping and equipment systems are filled with their normal operating fluids. Crew and effects are at their normal values. Consumables (provisions, potable water and fuel) are at 50% capacity. Ammunition and/or cargo is at 100% capacity. This condition is normally used for range and speed calculations.

Light Arrival : Along with all the Lightship loads, the vessel has all systems charged meaning that all fresh water, cooling, lubricating, hydraulic and fuel service header tanks, piping and equipment systems are filled with their normal operating fluids. Crew and effects are at their normal values. Consumables (provisions, potable water and fuel) are at 10% full load. Ammunition and/or cargo is at 100% capacity.

Additionally: Worst Operating Condition is a loosely defined condition that may have the least freeboard or least intact stability (or both). This condition forms the baseline for the Damage Stabilty assessment.