Question 1

As Chief Mate on a product tanker loading at Rotterdam, your examiner asks: "What specific stability and structural considerations apply to tanker loading operations that differ from a general cargo vessel?"

Accepted Answer

Tanker-specific considerations: (1) Free surface effect from multiple slack cargo tanks simultaneously — during loading/discharging many tanks are partially full at the same time, creating large combined free surface effects that can critically reduce GM; (2) the loading sequence must be planned to maintain GM above minimum throughout — the loading plan (pre-arrival calculation required for tankers) must show GM at each step; (3) structural: local deck loading from high-density cargo (crude oil 0.82-0.86 t/m3, some products >1.0 t/m3); longitudinal bending moments from uneven tank filling; (4) vapour pressure and inert gas management during loading — cargo tanks must be inerted before loading and IG pressure maintained; (5) tank overflow/topping-off procedures to prevent spill. Tanker stability management is one of the most complex aspects of Chief Mate practical competency. The FSE problem in tankers: a large product tanker may have 20-30 cargo tanks plus ballast tanks — if 10 cargo tanks are simultaneously slack during operations, the combined FSE can reduce effective GM by 1-2 metres. This is why the loading/discharging sequence plan must be calculated step by step. IBC Code (chemical tankers) and IBC Code (oil tankers) both require pre-operational cargo calculations. For tankers over 150 GT: the IOPP Certificate confirms approved Oil Record Book Part II (cargo operations record). Inert gas systems: SOLAS II-2/4 requires all crude oil tankers 20,000 DWT+ and product tankers 8,000 DWT+ to be fitted with an inert gas system — IG maintains tanks at slight positive pressure with

Question 2

As Chief Mate, you receive a Dangerous Goods Declaration for 12 drums of methyl ethyl ketone peroxide (Class 5.2 — organic peroxide). The manifest states "Type C." Your examiner asks what your responsibilities are before loading.

Accepted Answer

Before loading Class 5.2 organic peroxides: verify the Dangerous Goods Declaration is complete and accurate (UN number, proper shipping name, class, packing group, flashpoint, emergency contact). Check the IMDG Code entry for MEKP Type C — organic peroxides have temperature control requirements (SADT — self-accelerating decomposition temperature) and require controlled temperature stowage. Verify the shipper has provided a Certificate of Analysis confirming temperature control requirements are met. Check segregation against other cargo — Class 5.2 must be segregated from flammable materials. Confirm the ship has the required equipment (temperature monitoring, fire extinguishers of correct type). Inform master and company if any requirements cannot be met. The Chief Mate signs the cargo receipt — this is a legal acknowledgement of receipt in apparent good order. Organic peroxides (Class 5.2) are among the most dangerous IMDG cargoes — they can decompose exothermically and trigger fires or explosions. MEKP (Methyl Ethyl Ketone Peroxide) is used in fibreglass manufacturing and is highly reactive. The IMDG Code Subdivision 5.2 lists organic peroxides by type (A through G) — Type A is prohibited from sea transport; Type B requires temperature control and specific packaging. The SADT (Self-Accelerating Decomposition Temperature) is the minimum temperature at which the substance will decompose in the packaging used — if ambient temperature approaches SADT, cooling must be provided. At Chief Mate level, the examiner expects candidates to know: (a) the special provisions for the specific cargo; (b) the temperature monitoring and emergency cooling requirements; (c) stowage requirements (often "on deck away from living quarters" or "under deck in a cool, well-ventilated space"). Responsibility is shared — the shipper provides the declaration, the Chief Mate verifies it is plausible and meets carriage requirements.

Question 3

As Chief Mate of a 15-year-old Handymax bulk carrier, your examiner asks about the structural hazards specific to bulk carriers and what pre-loading inspections are required.

Accepted Answer

Bulk carrier structural hazards: transverse frames and frames at the lower hopper angles are susceptible to corrosion — section loss reduces capacity to withstand cargo and water pressure; topside tank inner structure (frames, longitudinals) can corrode from condensation; hold bilge systems can become blocked leading to flooding; hatch coaming knees and corners are high-stress areas prone to cracking. Pre-loading inspections required: visual inspection of all cargo hold frames for excessive corrosion, cracks, or deformation; measure any suspect frame section loss against class thickness limits; inspect bilge wells and ensure suctions are clear; test bilge systems before loading; verify hatch cover weathertightness; check hold structural condition report in class records. A "substantiated doubt" of structural deficiency found by PSC can require survey before departure. Bulk carrier structural safety has been a major IMO focus since the catastrophic losses of the 1980s-1990s (Derbyshire, Flare, Melete, Arktea — all total losses with all crew). The Enhanced Survey Programme (ESP) for bulk carriers (IMO Res. A.744(18)) requires detailed close-up surveys and thickness measurements at defined intervals. But between class surveys, the Chief Mate has a duty of care to identify visible deterioration. The IMO Guidelines for Surveys of Aged Bulk Carriers (MSC/Circ.1040) and IACS common structural rules address corrosion margin and allowable section loss. In practice: a frame with visible wastage (deep pitting, section loss, deformation) in a high-stress location (lower bracket area, bilge strake connection) can constitute a class deficiency requiring steel renewal before further loading. The Chief Mate is the primary person on board with technical knowledge to identify these issues — if in doubt, seek a class surveyor before loading heavy ore cargo.