Ice accumulating on the superstructure adds mass high up on the ship. This raises the centre of gravity (G), decreasing the metacentric height (GM). A lower GM reduces stability, making the ship more tender (more easily rolled) and increasing the period of roll. The ship becomes more susceptible to capsizing.

Wind:

• High freeboard or tall superstructures increase windage, leading to a greater rolling effect.
• Rolling caused by wind reduces stability, especially if the ship remains heeled for a prolonged period.

Waves:

• Large waves, especially when the ship is on the crest, can cause a significant loss of stability due to reduced underwater buoyant volume.
• The ship may develop excessive heeling or capsizing tendencies.
• Long ships are more vulnerable to wave action due to greater surface exposure, further reducing stability.

Consumption of fuel and water:

• Stability depends on the location of consumed or emptied tanks. Loss from low-level tanks increases G and decreases stability, while consumption from high-level tanks lowers G, increasing stability.

Ballast exchange or transfer:

• Transferring or exchanging ballast affects GM based on tank locations. Removal of low ballast raises G, while adding ballast low down lowers G and improves stability.

Sea conditions:

• Rolling and pitching caused by waves and wind can disrupt stability and amplify heeling or capsizing risks.

Ice formation:

• Ice buildup on decks or superstructures raises G, reducing GM and stability.

Shifting of cargo:

• Movement of cargo can create a list or cause instability if the shift raises the centre of gravity or reduces symmetrical weight distribution.

Side Compartments (Port/Starboard):

• Bilging a side compartment creates a virtual loss of GM due to the asymmetric flooding. This results in excessive list and increases the danger of capsizing.

Forward or Aft Compartments:

• Bilging forward or aft of the midship causes trim by head or stern, respectively.
• Reserve buoyancy is reduced or lost, significantly decreasing stability.
• Complete loss of reserve buoyancy results in sinking.

• During dry docking, as water is pumped out, the stern settles on the keel blocks first, creating an upthrust.
• This upthrust causes a virtual reduction in GM, which can destabilize the ship.
• If GM becomes negative, the vessel may heel to one side or slip off the keel blocks, potentially leading to capsizing.
• It is critical to ensure a positive GM during the entire dry docking process to maintain stability.