Stability & Cargo Safety Flashcards

What is the purpose of the International Maritime Dangerous Goods (IMDG) Code?

Answer: To regulate the safe stowage, handling, and carriage of dangerous goods by sea, specifying hazard classifications and segregation requirements

The IMDG Code is the international standard for carrying dangerous goods by sea, covering classification of hazards (9 classes), packaging, marking, labelling, documentation, stowage, and segregation requirements. It is mandatory under SOLAS for international voyages.

What is 'securing of cargo' and why is it critical to ship stability?

Answer: Lashing and blocking cargo to prevent shifting in a seaway — shifted cargo creates a listing moment that may lead to capsizing

Cargo securing prevents cargo shift during rolling, pitching, and heaving. If cargo shifts to one side, it creates a permanent listing moment that reduces the vessel's righting moment on that side and, in severe cases, can reduce stability enough to cause capsizing.

What is 'angle of loll' and what does it indicate?

Answer: An angle at which a vessel with negative GM finds a stable position of equilibrium on its side — it indicates the vessel is in a dangerous negative GM condition

Angle of loll occurs when a vessel has negative GM — it is unstable at the upright position and will flop to one side until it reaches an angle where B moves out enough to create a positive righting lever. It indicates negative GM and is a dangerous precursor to capsizing.

What is the correct response if a vessel develops an angle of loll at sea?

Answer: Move weight (ballast, water) from high positions downward to lower the G and restore positive GM — do not ballast only to the high side

To correct angle of loll, GM must be made positive by lowering G. Adding ballast low down (not high) and redistributing high weights lower reduces G. Adding water only to the high-side ballast tanks first can make the situation worse by adding free surface effect.

What is a vessel's 'load line' (Plimsoll line)?

Answer: A series of marks on the hull showing the maximum legal draft in different water types and seasons — the vessel must not be loaded below these marks

Load lines (Plimsoll marks) are internationally mandated marks showing the maximum loading depth (minimum freeboard) in different conditions: Summer, Winter, Winter North Atlantic, Tropical, Fresh Water, and Tropical Fresh Water. Submerging the appropriate mark is illegal and dangerous.

What is 'freeboard' and why is it important for ship safety?

Answer: The height of the main deck above the waterline — it represents the reserve buoyancy and provides protection against flooding and wave boarding

Freeboard is the distance from the waterline to the upper deck at its lowest point. It represents the vessel's reserve buoyancy — the amount of hull above water that, if flooded, would sink the vessel. Adequate freeboard also prevents waves from boarding the deck.