What is cross-flooding?

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Cross-flooding ducts are used to provide the necessary equalization across the ship in order to decrease the heeling angle. The elapsed time for this passive counteraction depends on the arrangement of the ducts and the tanks.

How does permeability affect the stability of the ship?

Permeability of a space in a ship is the percentage of empty volume in that space. Permeability is used in ship survivability and damaged stability calculations in ship design. In this case, the permeability of a space is a percentage from 0 to 100.

What is the damage stability of the ship?

The damage stability rules for the ships would be something like… The ship should be able to survive the breach (flooding) of any one (two or three) compartment. To check if the ship would comply with this damage stability requirement, the floodable length curve is superimposed on the ship’s plan.

What is intact stability and damage stability?

First, Intact Stability. This field of study deals with the stability of a surface ship when the intactness of its hull is maintained, and no compartment or watertight tank is damaged or freely flooded by seawater. Secondly, Damaged Stability.

What arrangement may be installed in passenger ships to reduce unsymmetrical flooding in damaged condition?

Cross-flooding ducts are used to equalize asymmetric flooding and, thus, to decrease the heel angle of a ship in an emergency.

What are the factors affecting ship stability?

Stability overview Stability is determined by the force of buoyancy provided by the underwater parts of a vessel, coupled with the combined weight of its hull, equipment, fuel, stores and load. These forces can also be adversely affected by the prevailing weather conditions and sea-state.

What makes a ship unstable?

Stability of a ship is significantly reduced due to build-up of ice on it superstructure. It not only causes unwanted angles of list, but also unwanted trim conditions. Often, list due to icing of superstructures is a result of asymmetrical accumulation of ice, which causes the center of gravity of the ship to shift.

Why it is important to maintain ship stability at all times?

Vessels sustain different and sometimes really heavy environmental conditions and other forces such as seawater, wind, internal mass weight, waves, free surface effect etc. Therefore, it is essential that the vessel remains stable both in still water and in turbulent seas.

What are the conditions needed for ship’s stability?

A ship is seaworthy if it fulfills two important stability criteria- Intact and Damage stability. Initial GM or metacentric height should not be less then 0.15 m. Righting lever GZ should be at least 0.2 m and angle of heel Ѳ ≥ 30̊. Maximum righting lever should occur at heel >30̊ preferably but not less than 25̊.

What are the conditions needed for stability?

Intact conditions

Lightship or Light Displacement.
Full load departure or full displacement.
Standard condition.
Light arrival.

What keeps the ship stable?

The ship is stable because as it begins to heel, one side of the hull begins to rise from the water and the other side begins to submerge. This causes the center of buoyancy to shift toward the side that is lower in the water.

How to check if the ship will comply with the floodable length?

To check if the ship would comply with this damage stability requirement, the floodable length curve is superimposed on the ship’s plan. Then one compartment by one, the damage stability compliance is checked. The length of the assumed damaged compartment is plotted vertically at the center of the compartment.

What is a floodable length curve?

The ship should be able to survive the breach (flooding) of any one (two or three) compartment. To check if the ship would comply with this damage stability requirement, the floodable length curve is superimposed on the ship’s plan.

What is the purpose of cross flooding ducts?

What is the initial heeling angle before the cross flooding?

The flooding on the upper decks is assumed to be instantaneous. As a result, the initial heeling angle before the cross-flooding is 5.2°. The damage scenario is illustrated in Fig. 18. The total volume for cross flooding water, W in Eq. (1), is about 389 m 3.