MCA CoC Stability & Cargo Safety 2 — Questions and Answers
Question 1: What is the purpose of the International Maritime Dangerous Goods (IMDG) Code?
- To regulate the safe stowage, handling, and carriage of dangerous goods by sea, specifying hazard classifications and segregation requirements (Correct answer)
- To regulate the packaging of goods for land transport only
- To identify prohibited cargo types for UK coastal vessels
- To set customs procedures for hazardous cargo imports
Correct 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.
Question 2: What is 'securing of cargo' and why is it critical to ship stability?
- Lashing and blocking cargo to prevent shifting in a seaway — shifted cargo creates a listing moment that may lead to capsizing (Correct answer)
- Securing only applies to deck cargo — hold cargo is held by gravity
- Cargo securing is only needed in heavy weather
- Securing only prevents cargo damage, not stability problems
Correct 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.
Question 3: What is 'angle of loll' and what does it indicate?
- 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 (Correct answer)
- The angle at which the cargo begins to shift
- The maximum recommended heel angle for normal operations
- A permanent list due to asymmetric loading
Correct 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.
Question 4: What is the correct response if a vessel develops an angle of loll at sea?
- Move weight (ballast, water) from high positions downward to lower the G and restore positive GM — do not ballast only to the high side (Correct answer)
- Ballast the high side immediately to bring vessel upright
- Increase speed to generate dynamic stabilising forces
- Alter course to put the sea on the bow to reduce rolling
Correct 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.
Question 5: What is a vessel's 'load line' (Plimsoll line)?
- 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 (Correct answer)
- The waterline when the vessel is loaded to its maximum cargo capacity
- The draft mark used for harbour dues calculation
- The paint waterline showing the design waterline
Correct 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.
Question 6: What is 'freeboard' and why is it important for ship safety?
- The height of the main deck above the waterline — it represents the reserve buoyancy and provides protection against flooding and wave boarding (Correct answer)
- The height of the bridge above sea level
- The clearance between the hull bottom and the seabed
- The distance between the waterline and the top of the hatch covers
Correct 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.
MCA CoC Stability & Cargo Safety 2
What is the purpose of the International Maritime Dangerous Goods (IMDG) Code?