MARINA Chief Mate / Master Theoretical Exam common mistakes
MARINA Chief Mate / Master Theoretical Exam · Understand the traps and how to avoid them.
Calculating a great-circle or Mercator sailing result and reporting it without converting the final course to the 000°–360° true convention or without applying magnetic/variation correction when the question asks for a compass course.
Candidates practise the spherical trigonometry formula but rush the final step, and exam figures often give variation and deviation in a separate sentence that is easy to skip.
What to do instead
Adopt a fixed finishing checklist for every sailing problem: quadrant-to-360° conversion, then true-to-magnetic-to-compass (or reverse) with variation and deviation applied in the correct sign order, written out line by line before selecting the answer.
Plotting a position fix from three bearings and simply averaging the three lines instead of constructing the cocked hat and resolving the systematic error.
Training focuses on the single position-line transfer, and candidates do not rehearse the rule that a constant error shifts all lines the same way, so they treat the triangle as random scatter.
What to do instead
Work through cocked-hat cases deliberately: if the triangle is equilateral, treat it as random and take the centre; if the three lines share a consistent offset, shift each by the same amount opposite the suspected compass or gyro error before plotting the fix.
Computing a ship's deadweight or cargo intake by subtracting the wrong lightship figure, or ignoring constants, fresh water, and stores when converting from displacement to cargo capacity.
The displacement–deadweight–cargo chain has several subtractions and candidates memorise one formula without tracking which tonnage each figure represents.
What to do instead
Always build a load-line/tonnage table in a fixed order (displacement at the load line, minus lightship, minus constants, fresh water, fuel, stores, ballast) and state the units and the tonnage basis (metric, displacement) at each line before computing cargo.
Answering a stowage question about heavy lift or concentrated load without checking deck load capacity or tank-top strength, giving only the stability answer.
Candidates separate stability and structural strength in their heads and answer the part of the question that is easiest to calculate.
What to do instead
For every cargo-loading question, run a two-part check: stability (GM, list, trim) and structural strength (deck load in t/m², tank-top limit, point loading under a heavy unit), and state both results explicitly even if only one is asked for.
Listing emergency actions in the wrong sequence, for example ordering abandon ship before mustering and accounting for all persons, or starting firefighting before the alarm and boundary cooling are established.
Candidates recall the individual actions but not the priority order, and under time pressure write whatever comes first.
What to do instead
Memorise short ordered mnemonics for each emergency (fire: alarm, muster, account for persons, isolate, boundary cool, attack; abandon ship: distress alert, muster, account for all, launch, clear the ship), and rehearse writing them in order in under two minutes.
Using the full block coefficient or the wrong free-surface correction when calculating the effect of a partially filled tank, or ignoring free surface entirely in the final GM.
Free surface is treated as a minor correction, and candidates forget it applies to any slack tank, not only to ballast.
What to do instead
Make free surface an explicit line in every stability calculation: list all slack tanks, apply the free-surface correction (FSM/displacement) to the fluid GM, and state the corrected GM before judging whether the ship complies with the intact stability criteria.
Describing a weather system or forecasting a change using only the isobar pattern without referencing the pressure tendency, the actual wind direction relative to the isobars, and the hemisphere.
Candidates learn the Buys Ballot rule as a formula and do not connect it to the observed wind veering or backing that signals an approaching front.
What to do instead
For every synoptic question, state four things: the hemisphere, the wind direction relative to the isobars (backing to the wind in the Northern Hemisphere low), the pressure tendency over the last three hours, and the expected change in wind and visibility as the system passes.
Answering a personnel-management or watchkeeping question with a general statement about 'good seamanship' instead of citing the specific STCW rest-hour, watch-schedule, or fatigue-management requirement.
Candidates treat management questions as opinion questions and do not revise the numerical limits in STCW and the ISM Code.
What to do instead
Revise and quote the hard numbers: minimum rest hours in any 24-hour and 7-day period, the maximum watch period, the requirement for a proper handover, and the master's overriding authority under the ISM Code, then frame the answer around those specifics.
Confusing MARPOL Annexes or applying the wrong discharge criterion, for example quoting the oil-record-book entry rule when the question is about garbage or sewage.
The annexes share similar structure and candidates memorise one set of distances and concentrations and apply it everywhere.
What to do instead
Build a one-page comparison table by annex (substance, discharge prohibition or criterion, distance from nearest land, record book required, special areas) and test yourself by covering one column at a time until each annex is distinct.
Describing a main-engine or auxiliary-system fault without linking the symptom to the specific component and the immediate operational response, or ignoring the ECDIS/ARPA settings that caused an electronic-navigation error.
Engineering and electronic-navigation questions are often treated as recall of component names rather than diagnosis, and candidates do not practise tracing a symptom through the system.
What to do instead
For engineering faults, answer in three steps: symptom, most probable component and cause, immediate action and isolation; for ECDIS/ARPA questions, always state the relevant settings (safety contour, scale, vector length, CPA/TCPA limits, chart datum) that would produce the reported error.