Iran Deck Officer (STCW II/2) Certificate of Competency Examination flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Great-circle distance formula

Distance d = R * arccos(sin φ1 sin φ2 + cos φ1 cos φ2 cos Δλ), where R = 6371 km or 3440.065 NM; φ latitude, λ longitude.

Initial great-circle course

Course C = atan2(sin Δλ cos φ2, cos φ1 sin φ2 − sin φ1 cos φ2 cos Δλ); measured from true north at departure point.

Mercator sailing DMP

Difference of meridional parts DMP = 7915.7 * log10(tan(45° + φ/2)) in minutes; used to compute course and distance on Mercator chart.

CPA and TCPA

CPA is the closest point of approach, perpendicular distance from origin to relative track; TCPA is time to CPA = along-track distance to CPA divided by relative speed.

Stowage factor

Volume occupied by unit weight of cargo (m³/t or ft³/t); used to calculate space required and cargo intake; includes broken stowage allowance.

IMDG segregation codes

Code 1 away from, 2 separated from, 3 separated by one compartment or hold, 4 separated by two compartments or hold, X see segregation flowchart.

Grain stability heel

Approximate angle of heel = (total grain heeling moment / displacement) × 12 degrees; must not exceed 12° or deck edge immersion, whichever first.

Draft survey cargo weight

Cargo weight = (displacement after − displacement before) corrected for density, trim, and deductibles; use hydrostatic tables and draft readings.

Metacentric height GM

GM = KM − KG; positive GM indicates stable equilibrium, negative GM indicates unstable (loll); GM affects roll period and stability.

Free surface effect

Reduction in effective GM due to free surface of liquids in tanks: FSC = (i × ρ) / Δ, where i is second moment of free surface area.

Angle of loll

Condition when GM = 0; ship lists to either side; correct by lowering KG (ballast bottom tanks) before adding weight; avoid slack tanks.

Load line marks

Marks S, W, T, F, TF, FWA; fresh water allowance FWA = Δ / (4 × TPC) mm; ensure draft not exceed applicable mark.

Two-stroke diesel scavenging

Uses uniflow scavenging: air enters via scavenge ports, exhaust via valve; firing order and timing set by camshaft; indicator diagram checks power balance.

Fuel oil viscosity control

HFO heated to 10–15 cSt at injection; viscosity controller maintains set point; too high viscosity causes poor atomisation and incomplete combustion.

Steering gear SOLAS test

Main steering gear capable of 35° port/starboard in 28 s at full speed; test before departure; emergency steering drill required.

Oily water separator limit

15 ppm alarm and automatic stopping device; discharge overboard only with approval and oil record book entry; monitor separator function.

Beaufort scale force 8

Gale: wind speed 34–40 knots; sea state rough to very rough; waves 5.5–7.5 m; avoid heavy weather damage.

Buys Ballot's law

In Northern Hemisphere, stand with back to wind - low pressure is to your left; Southern Hemisphere reversed; used to locate storm centres.

Tropical revolving storm sectors

Dangerous semicircle: right in N Hemisphere, left in S Hemisphere; navigable semicircle is opposite; avoid the dangerous semicircle and storm centre.

Advection fog

Forms when warm moist air moves over cold sea surface; common in coastal areas; reduces visibility; use radar and sound signals.

ECDIS safety contour

User-defined depth contour that triggers alarms; should be set to safe navigable depth; ECDIS must not be relied upon solely for navigation.

Radar X-band vs S-band

X-band (9 GHz) gives high resolution for short range; S-band (3 GHz) penetrates rain and sea clutter for longer range; use both for collision avoidance.

STCW rest hours

Minimum 10 hours rest in any 24-hour period and 77 hours in any 7-day period; rest may be divided into no more than two periods.

AIS limitations

AIS provides MMSI, course over ground, speed over ground, and navigational status; not to be used for collision avoidance alone; use radar and visual lookout.

Rule 13 overtaking

Overtaking vessel keeps out of the way until finally past and clear; any doubt = overtaking; applies in restricted visibility and narrow channels.

Rule 14 head-on

When two power-driven vessels meet head-on, both alter course to starboard and pass port-to-port; no right of way.

Rule 15 crossing

Vessel with other on her starboard side gives way; avoid crossing ahead; take early and substantial action.

Rule 19 restricted visibility

Reduce speed, sound fog signals, and if risk of collision, take avoiding action; no right of way; use radar and safe speed.

MARPOL Annexes

Annex I oil, II noxious liquid substances, III harmful substances in packaged form, IV sewage, V garbage, VI air pollution; each has discharge restrictions.

MLC 2006 minimum age

Minimum age for seafarers is 16; night work restrictions for young seafarers; hours of work and rest; repatriation rights.

GMDSS distress alert

MAYDAY spoken three times; DSC on VHF Ch 70, MF/HF; follow with voice on Ch 16; use Inmarsat if available.

SMCP message markers

QUESTION, ANSWER, REQUEST, INSTRUCTION, ADVICE, WARNING, INFORMATION, INTENTION; used to clarify intent in safety communications.