Question 1

Your vessel is loading sawn timber on deck. Your examiner asks: "What regulations govern timber deck cargo, and what special provisions does it carry for load lines?"

Accepted Answer

Timber deck cargo is governed by the Code of Safe Practice for Ships Carrying Timber Deck Cargoes (TDC Code, IMO). Requirements include: timber must be stowed as solidly as possible; height of deckload must not impede navigation or safe working; lashings must be fitted per the CSS Code; access fore and aft must be maintained (lifelines or walkways). Load lines: ICLL 1966 Schedule II (Timber Load Lines) allows a vessel carrying a timber deck cargo of defined specification to load to a more favourable timber load line mark — the timber mark is 1/3 of the freeboard above the corresponding normal mark. This concession recognises the buoyancy contribution of a well-secured timber deckload. The TDC Code and ICLL 1966 Annex II (Timber Load Lines) work together. The timber load line is applicable only when: (a) the timber deck cargo meets the definition in ICLL Annex II (extends at least from superstructure to superstructure, or in the absence of a superstructure, at least between the forward and after ends of the cargo hatch); (b) special lashing arrangements are fitted; (c) double-line lifelines are rigged. The timber marks (LS, L, LT, LW, LWNA, LF, LTF) are positioned above the corresponding standard marks — vessels loading to timber marks are deeper but this is compensated by the acknowledged buoyancy of the deckload. An OOW on a timber carrier must understand when the timber mark applies and ensure it is not exceeded. Wet or saturated timber weighs significantly more than stated — cargo weight assumptions must account for moisture content change during a long ocean voyage.

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.