Question 1

Your examiner asks: "What is the Verified Gross Mass (VGM) requirement for containers, and what are the consequences of shipping a container without a VGM?"

Accepted Answer

SOLAS VI/2 amendments (in force 1 July 2016): every packed container must have a Verified Gross Mass (VGM) declared by the shipper before it can be loaded onto a ship. The VGM is obtained by either: Method 1 — weigh the packed container on a calibrated instrument; or Method 2 — weigh all cargo items, packaging, and materials plus the tare weight of the container using a certified method. A container without a VGM declaration cannot be loaded. The terminal and ship must use the VGM in the stability and stow plan. Misdeclared container weights are directly linked to structural failures, crane collapses, and vessel stability incidents. The VGM requirement was introduced after investigations (including the MSC Napoli, CMA CGM Bianca, and numerous container crane collapses) identified widespread misdeclaration of container weights — sometimes by 30-50% above declared mass. The SOLAS VI/2 amendment is mandatory for all SOLAS contracting states. Method 1 (weighing the packed box) is the most accurate; Method 2 (summing components) requires a certified process by the shipper and is accepted subject to documentary proof. The VGM must be communicated to the master (or master's representative — typically the terminal planning department) before loading. At OOW level during cargo operations: if a container arrives without a VGM documentation, operations must stop for that container. Accepting containers without VGM is a violation the master and officer in charge of cargo operations are responsible for. The loading plan stability calculations are only valid if based on correct VGM data.

Question 2

Your examiner asks: "State the nine classes of dangerous goods under the IMDG Code and give one example of each." Give a complete answer.

Accepted Answer

Class 1: Explosives (e.g. detonators, fireworks). Class 2: Gases — 2.1 Flammable (LPG), 2.2 Non-flammable/non-toxic (compressed air), 2.3 Toxic (chlorine). Class 3: Flammable liquids (petrol, acetone). Class 4: Flammable solids — 4.1 Flammable solids (matches), 4.2 Spontaneously combustible (wet fishmeal), 4.3 Dangerous when wet (sodium, calcium carbide). Class 5: Oxidising substances — 5.1 Oxidisers (ammonium nitrate), 5.2 Organic peroxides. Class 6: Toxic and infectious — 6.1 Toxic (pesticides), 6.2 Infectious substances. Class 7: Radioactive. Class 8: Corrosives (battery acid, caustic soda). Class 9: Miscellaneous dangerous goods (lithium batteries, dry ice). The IMDG Code (International Maritime Dangerous Goods Code, made mandatory under SOLAS VII/3) uses UN-based classifications. Key points for OOW orals: Class 4 has three subdivisions — 4.2 (spontaneously combustible materials including wet fishmeal which has caused numerous bulk carrier fires) and 4.3 (dangerous when wet — water reacts to produce flammable gases) are the most hazardous from a watchkeeping perspective. Class 9 (lithium batteries) has become increasingly significant — lithium battery fires in containers and car carriers have caused major incidents (e.g. Felicity Ace). The IMDG Code is updated biennially; the 2022 edition (Amendment 41-22) is the current edition. Segregation requirements between classes are specified in IMDG Chapter 7 — an OOW must understand that certain classes cannot be stowed in the same space (e.g. oxidisers and flammables).

Question 3

You are loading a general cargo consignment. The cargo plan shows ammonium nitrate (Class 5.1) in Hold 2 and petroleum products in drums (Class 3) in Hold 3, which is adjacent. Is this acceptable under the IMDG Code?

Accepted Answer

Ammonium nitrate (Class 5.1, oxidiser) and petroleum products (Class 3, flammable liquids) require segregation of "away from" (separated by an intervening space or hold) at minimum. Adjacent holds sharing a common bulkhead do not satisfy "away from" — the cargoes must be in non-adjacent holds with at least one hold separation. Check the IMDG Segregation Table (Chapter 7.2): oxidisers and flammable liquids require at minimum "away from" and in some cases "separated from." This loading plan requires amendment. IMDG Code Chapter 7.2: segregation categories: "away from" (minimum separation of 3m horizontally in the same space, or in different compartments/holds); "separated from" (separated by a complete compartment or hold — i.e. at least one intervening space); "separated by a complete compartment or hold" and "separated longitudinally by an intervening complete compartment or hold." Ammonium nitrate as an oxidiser can cause catastrophic decomposition if contaminated with fuel oil (the Beirut Port explosion 2020, Texas City 1947 were both ammonium nitrate events). The segregation requirement between Class 5.1 and Class 3 is "away from" at minimum — adjacent holds sharing a bulkhead do not satisfy this. An OOW discovering an incorrect cargo plan before loading must stop operations and refer to the Chief Officer and master. The IMDG Segregation Table in Chapter 7.2.4 provides the complete matrix of segregation requirements between all classes.