Question 1

Your examiner asks: "What checks must you make on hatch covers before a heavy weather ocean passage, and what SOLAS requirement covers watertight integrity of cargo hatch covers?"

Accepted Answer

Pre-passage hatch cover checks: inspect all hatch cover cleats, dogs, and wedges are fully tightened in the correct sequence (from centre outwards); check rubber sealing gaskets for cracks, deterioration, and correct compression — gasket compression is the primary sealing mechanism; hose test (water test) the hatch coamings using a jet of water along the seal perimeter while checking for ingress below; check all drain channels are clear; verify cross-joints are properly aligned and secured; confirm covers are not warped or deformed. SOLAS II-1/15 requires hatch covers and their fastenings to be weathertight. Classification rules specify the design standard. Failure of hatch covers in heavy weather is cited in numerous bulk carrier loss investigations (Derbyshire, Flare, Arktea). Hatch cover failure in heavy weather has been identified as a primary or contributing cause in numerous bulk carrier total losses. The Korean Register of Shipping and classification societies publish detailed inspection guidance. Key points: (a) rubber gasket compression — the gasket must compress sufficiently to seal when the hatch is closed; a gasket showing cracks, hardening (oil contamination causes rubber to harden), or insufficient compression will leak; (b) hose testing procedure — use a 3-bar water jet directed at the seal from outside; an assistant below watches for ingress — this test should be performed after any significant hatch work or before a heavy weather passage; (c) cleat tightening sequence matters — starting from the ends can cause the hatch to cant and not seal properly in the centre. The formal UltraSound test (using a sound transmitter in the hold and an ultrasonic detector outside) is the most sensitive test method, increasingly used by surveyors. An OOW finding a leaking hatch on passage must inform the master immediately and monitor cargo hold bilge levels.

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.