Croatia Master Mariner flashcards

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

Meridional parts formula

MP = 7915.7 × log10 tan(45° + Lat/2). Used to convert latitude into Mercator projection distance so that a straight rhumb line can be plotted on a Mercator chart.

Composite great circle

A great-circle route limited by a maximum latitude. The route follows the great circle until it reaches the limiting parallel, runs along it, then follows another great circle to the destination.

Running fix

A position obtained by advancing an earlier line of position along the course and distance run, then transferring it parallel and intersecting it with a later LOP.

Rule of twelfths

Approximation of tidal height change over six hours: 1/12, 2/12, 3/12, 3/12, 2/12, 1/12 of the range after high or low water slack.

ECDIS safety contour

The depth contour set by the navigator; areas shallower than it are highlighted as unsafe. It must be checked against the ship's draught and under-keel clearance.

Stowage factor

Volume occupied per unit mass of cargo, expressed in cubic metres per tonne. Used with deadweight and broken stowage to plan cargo distribution.

Broken stowage

The proportion of a cargo space not occupied by cargo due to shape, dunnage and access. Expressed as a percentage and increases the effective stowage factor.

IMDG segregation code 4

Requires dangerous goods to be separated by two bulkheads or one bulkhead and a deck, or by a complete compartment or hold.

Grain Code heeling moment

The heeling moment calculated from the assumed shift of grain at 12 degrees of heel, or the angle of flooding if less, compared with the allowable value in the Grain Loading Booklet.

VGM under SOLAS VI/2

Verified gross mass of a packed container, obtained by weighing or by calculation and signed by an authorised person, must be provided before loading.

ISM Code master's authority

The master has overriding authority and responsibility to make decisions regarding safety and pollution prevention, and may request company assistance when needed.

STCW rest hours

Minimum rest of 10 hours in any 24-hour period and 77 hours in any 7-day period; rest may be divided into no more than two periods, one at least 6 hours.

Permit to work

A formal written authorisation for high-risk tasks such as hot work, enclosed-space entry or working aloft, listing precautions, isolations, and sign-off by authorised persons.

Free surface correction

FSC = Σ(ρ·i)/(ρ_ship·Δ). It reduces the effective metacentric height when liquid free surfaces exist in tanks, reducing transverse stability.

Angle of loll

The angle at which a ship with negative initial GM rests in stable equilibrium. Calculated as tan θ = √(2·GM/BM) using the magnitude of negative GM.

IMO intact stability GM criterion

Initial metacentric height must be at least 0.15 m for ships covered by the 2008 Intact Stability Code, evaluated in the worst service condition.

Probabilistic damage stability

SOLAS II-1 method using the attained subdivision index A, calculated as the sum of p_i·s_i over damage cases, compared with the required index R.

Buys Ballot's law

In the Northern Hemisphere, with your back to the wind, low pressure lies to your left. In the Southern Hemisphere, low pressure lies to your right.

Dangerous semicircle

In a Northern Hemisphere tropical revolving storm, the half of the storm to the right of the track, where winds and seas are most hazardous and the storm centre approaches.

Semi-diurnal tide

A tide with two high and two low waters per tidal day, driven mainly by the M2 constituent with a period of about 12 hours 25 minutes.

Spring and neap tides

Spring tides occur near new and full moon when solar and lunar forces align, giving the largest range. Neap tides occur at quadrature with the smallest range.

Hague-Visby seaworthiness duty

The carrier must exercise due diligence to make the ship seaworthy before and at the beginning of the voyage; breach removes the package limitation defence.

General average

A sacrifice or expenditure intentionally and reasonably made for the common safety of ship and cargo, apportioned among the parties by their arrived values.

Limitation of liability

Under LLMC 1976/1996, shipowner liability for certain maritime claims is limited by reference to the ship's tonnage, with separate limits for property and personal claims.

Innocent passage

Under UNCLOS, navigation through the territorial sea that is not prejudicial to peace, good order or security; submarines must navigate on the surface and show their flag.

MARPOL Annex VI sulphur limit

Global sulphur content of fuel oil limited to 0.50% m/m since 2020, and 0.10% m/m in designated emission control areas, unless an approved equivalent arrangement is used.

MLC 2006 hours of work

Maximum 14 hours of work in any 24-hour period and 72 hours in any 7-day period, or minimum rest of 10 hours and 77 hours respectively.

Load Line marks

Marks painted on the ship's side showing maximum permitted draught for summer, winter, tropical, freshwater and timber conditions, measured from the deck line.

SFOC

Specific fuel oil consumption, expressed in grams of fuel per kilowatt-hour of shaft power. Used to compare engine efficiency and calculate voyage fuel consumption.

NPSH available

Net positive suction head available at a pump inlet, calculated from atmospheric pressure, vapour pressure, static head and suction friction losses. Cavitation occurs if it falls below NPSH required.

Steering gear changeover

SOLAS requires two independent power units and changeover from one to the other within 45 seconds; main and auxiliary gear tested before departure.

DSC distress frequency

MF 2187.5 kHz, VHF channel 70 and HF frequencies 4207.5, 6312, 8414.5, 12577 and 16804.5 kHz are used for digital selective calling distress alerts.

NAVTEX frequencies

518 kHz for international, 490 kHz for national and 4209.5 kHz for tropical broadcasts. Reception range is typically 200 to 400 nautical miles.

SART operation

A 9 GHz radar transponder that responds to radar pulses with twelve dots, showing the survival craft position on nearby radar displays up to about 8 nautical miles.

CO2 fixed fire system

A total-flooding system for machinery spaces requiring about 30–35% of the gross volume; released only after all personnel are accounted for and the space is sealed.

Williamson turn

A man-overboard manoeuvre: hard over to one side, then hard over the other after 60 degrees of turn, bringing the ship back on a reciprocal track.

Emergency generator start

SOLAS requires the emergency generator to start automatically and supply the emergency switchboard within 45 seconds of a main power failure.

Oil Record Book

MARPOL Annex I record with Part I for machinery space operations and Part II for tanker cargo/ballast operations; entries signed by the officer in charge and master.

Garbage discharge distances

Food waste comminuted to 25 mm or less may be discharged at least 3 nm from land; uncomminuted food waste at least 12 nm; plastics are never discharged.

Ballast water D-2 standard

Limits on viable organisms in discharged ballast water: less than 10 organisms per m³ for 10–50 µm size class, and less than 10 organisms per mL for smaller classes.

Enclosed space entry precautions

Atmosphere tested for oxygen, flammable gas, H2S and CO; permit issued; standby person at entrance; communications and rescue equipment ready; ventilation maintained.