Chief Mate CoC common mistakes
Chief Mate CoC · Understand the traps and how to avoid them.
When asked to plan a passage, the candidate lists waypoints and distances but never states the under-keel clearance policy, abort/ contingency anchorages, or the no-go depth contour, so the plan cannot be audited for safety.
Candidates memorise the plotting mechanics (courses, distances, ETA) from college chartwork and treat the plan as a navigation exercise rather than a risk document. They have rarely had to defend a plan to a master or pilot, so they omit the decision points that make a plan usable in practice.
What to do instead
Adopt a fixed plan template that forces the safety layer: for each leg state minimum UKC and its source (squat, heel, swell allowance), the controlling depth contour, safe abort positions with anchoring depth and holding ground, wheel-over/ course-alteration points, and contingency ports. Practise writing it out for a 60-mile coastal passage in under 30 minutes until the template is automatic.
Calculates squat, UKC or tidal height only for the static still-water case and fails to apply the dynamic corrections - block coefficient effect, shallow-water increase, interaction with banks and passing ships, and the difference between under-keel clearance at the bow and at the stern when trimmed.
Formula recall is strong but the conditions of validity are weak; candidates plug numbers into a squat formula without checking whether the water depth-to-draught ratio puts the ship in the shallow-water regime where the formula's coefficient changes. Trim and heel effects are usually skipped entirely.
What to do instead
For every squat/UKC question, write the four checks before calculating: depth/draught ratio, block coefficient, speed through water, and trim/heel state. Learn one conservative rule set (e.g. squat proportional to Cb and V-squared, doubled in shallow water) and quote the assumptions explicitly in the answer.
Answers synoptic and weather-routeing questions by describing the isobars on the presented chart rather than diagnosing the three-dimensional system: upper-level flow, thermal gradients, frontal structure, and the likely 24-48 hour evolution including secondary lows and ridge building.
Training focuses on surface analysis and the Beaufort scale; candidates are not practised at reading 500 hPa charts, thickness, or forecast model spread, so they describe what is visible instead of forecasting what will happen. They also confuse local diurnal effects with synoptic forcing.
What to do instead
Practise the 'analyse, then forecast' drill: for each system state position, central pressure, movement vector, front type and the forcing (jet streak, thermal gradient), then commit to a 24-hour and 48-hour position with a confidence statement. Learn to compare two models and say which to trust and why.
Treats damage stability and flooding as a static calculation only, ignoring permeability of the flooded compartment, free surface effect, progressive flooding through open or failed boundaries, and the loss of stability at the angle of loll.
Candidates learn the lost-buoyancy method and damage control plan but often never apply permeability factors or consider how a collision bulkhead or watertight door status changes the outcome. The link between the damage control plan and the actual calculation is not made in training.
What to do instead
Work flooding problems in a fixed sequence: identify the compartment and its permeability, calculate the new KG and GM with free surface, plot the GZ curve, identify the angle of loll and range of positive stability, then state which boundaries must hold and what happens if each fails. Always cross-check against the damage control plan and cross-flooding arrangements.
Answers law questions by naming the convention (SOLAS, MARPOL, MLC) without identifying the specific regulation, the flag/port/coastal State obligation, and who holds the enforcement power in the scenario given.
Candidates study conventions as topic lists rather than as instruments with articles, regulations and enforcement architecture. They do not distinguish between the duty of the company, the master, the flag State and the port State, so the answer stays at headline level.
What to do instead
Build a one-page matrix for each major convention: instrument, key regulation numbers, who is obligated, who enforces, what the certificate or record is, and the penalty regime. Practise answering 'who must do what, under which regulation, and who checks it' for ten scenarios until it is reflex.
In collision regulation scenarios, the candidate identifies the give-way/stand-on status correctly but then gives an action that contradicts the rule - e.g. a stand-on vessel altering to starboard early, or a give-way vessel crossing ahead - and misapplies Rule 19 restricted visibility conduct.
Rules are learned as text, not as decision trees under time pressure. Candidates confuse 'may' with 'shall', forget the stand-on vessel's duty to hold course until risk of collision is deemed to exist, and mix Rule 14 head-on with Rule 15 crossing behaviour.
What to do instead
Drill scenarios aloud using a fixed script: determine vessel type and rule, state give-way/stand-on, state own action and timing, state what the other vessel should do, and state the fallback if it does not. Separately memorise Rule 19's three phases (safe speed, avoiding action, final action) and never import Rule 14/15 manoeuvres into fog.
Emergency response answers describe the alarm and the muster but omit the command structure: who takes bridge control, who is On-Scene Coordinator, the reporting chain to the company and coastal State, and the decision criteria for abandoning ship or requesting external assistance.
Candidates rehearse drills procedurally (alarm, muster, headcount) but are rarely tested on the decision-making layer. The ISM/SMS structure and the master's overriding authority are quoted as phrases without being applied to a scenario.
What to do instead
For each emergency type (fire, collision, flooding, man overboard, pollution), write a one-page decision card: initial actions, command roles, communications (internal, company, coastal State, insurers), decision gates and their criteria, and the record-keeping requirement. Rehearse it as a tabletop with a time-stamped timeline.
When asked about machinery or systems, the candidate answers with the operational symptom only and cannot explain the system layout, the failure mode, or the immediate bridge-level action - for example steering gear changeover, emergency generator start, or fuel changeover procedures for ECA compliance.
Deck candidates tend to treat the engine room as a black box and study systems only to the level needed for the oral, so they cannot reason about a failure. They also skip the regulatory drivers, such as SOLAS II-1 steering gear requirements or ECA fuel sulphur limits.
What to do instead
Learn each critical system as a block diagram with a failure mode for every block: steering (two pumps, changeover, emergency steering drill), electrical (main switchboard, emergency generator, 30-second auto-start), fuel (changeover timing, viscosity, sulphur), and bilge/fire pumps. For each, state the bridge action and the regulation behind the design.
Leadership and human element answers are given as generic statements about good communication and teamwork, with no reference to fatigue management, safety culture, just culture, behavioural markers, or the specific tools (near-miss reporting, toolbox talk, stop-work authority).
Candidates underestimate this domain and prepare it last, treating it as common sense. They have not learned the vocabulary of human factors - situation awareness, decision-making, communication, teamwork, leadership - or how STCW and the ISM Code frame them.
What to do instead
Prepare concrete examples from your own sea time for each behavioural marker, and learn the fatigue, rest-hour and fitness-for-duty requirements with numbers. Be ready to describe how you would run a toolbox talk, handle a near-miss report, or intervene with a senior officer, and link each to the SMS and STCW provisions.
Pollution prevention answers stop at 'follow MARPOL' without identifying the annex, the discharge criteria (rate, distance from land, speed, dilution), the required records (Oil Record Book, Garbage Record Book, bunker delivery notes) and the special area or ECA status of the position given.
Candidates learn MARPOL as a single topic and do not separate Annex I, IV, V and VI criteria, nor do they connect the geographic position in the question to special area status. Record-keeping obligations and the prohibition on false entries are under-prepared.
What to do instead
Build a discharge-criteria table by annex: substance, permitted discharge conditions, distance and speed limits, special area rules, and the record required. Practise identifying special areas and ECAs on a world map, and be ready to explain the master's duty when an illegal discharge or false entry is suspected.