GMA OOW Deck flashcards

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

Meridional parts

The cumulative length on a Mercator chart from the equator to a given latitude, computed as 7915.7 × log10[tan(45° + Lat/2)]; used to solve Mercator sailing problems.

Amplitude

The bearing of a celestial body at rising or setting measured from the observer's prime vertical, given by sin(amplitude) = sin(declination) / cos(latitude); used to check compass error.

Running fix

A position fix obtained by advancing an earlier position line along the course and distance run, then transferring it parallel to cut a later position line.

Set and drift

The direction toward which a current flows (set) and its speed (drift), found by comparing the dead reckoning position with the observed fix over a known interval.

Buys Ballot's law

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

Advection fog

Fog formed when warm, moist air moves over a colder surface and is cooled below its dew point; common over cold currents and in coastal areas.

Cold front passage

The boundary where cold air advances under warm air, producing a narrow band of heavy showers, squalls, a sharp pressure rise, and a wind veer after passage.

Beaufort force 8

A gale with mean wind speed of 34 to 40 knots; the sea is described as moderately high with breaking crests and streaks of foam.

Metacentric height

GM = KM − KG, the distance between the centre of gravity and the metacentre; a positive value gives initial stability and a negative value causes capsizing.

Free surface effect

The virtual rise of G caused by liquid moving freely in a partly filled tank; computed as FSC = (i × density) / displacement, and reduced by subdividing tanks.

Angle of loll

The angle at which a ship with negative GM lies when GZ returns to zero; corrected by lowering G, for example by filling low centre tanks.

Tons per centimetre

TPC = (waterplane area × water density) / 100; the mass in tonnes required to change the ship's mean draught by one centimetre.

Stowage factor

The volume in cubic metres occupied by one tonne of a particular cargo; used to calculate how much cargo a hold can carry.

IMDG segregation 3

A segregation requirement meaning the goods must be separated by one compartment or hold, or by a complete deck, from the other dangerous goods.

Draft survey

A method of determining cargo weight from the difference in displacement between initial and final draughts, corrected for density, ballast, fuel, and water changes.

Ship sweat

Moisture condensing on the ship's structure when warm moist air inside the hold meets a cold hull; prevented by ventilation when outside dew point is lower.

STCW rest hours

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

Muster list

A posted document assigning every person on board a station and duties for emergencies such as abandon ship, fire, and man overboard.

Document of Compliance

An ISM certificate issued to the company confirming its safety management system complies with the Code; a copy must be kept on board each ship.

Closed-loop communication

A communication method in which the receiver repeats back the order or message so the sender can confirm it was received and understood correctly.

Emergency steering test

A drill required at least every three months to verify that the emergency steering arrangement can be changed over and used to steer the ship.

Oily water separator limit

Equipment that separates oil from bilge water; discharge must not exceed 15 ppm, and a 15 ppm alarm and automatic stopping device must be fitted.

Two-stroke diesel cycle

A cycle completed in one revolution of the crankshaft, using scavenging air ports and an exhaust valve, with a power stroke every revolution.

Steering gear SOLAS test

The main steering gear must move the rudder from 35° one side to 35° the other in not more than 28 seconds at maximum ahead service speed.

Overtaking vessel

Under COLREG Rule 13, a vessel approaching from more than 22.5° abaft the beam; it must keep out of the way until finally past and clear.

Crossing rule

Under COLREG Rule 15, when two power-driven vessels cross, the one with the other on her starboard side keeps out of the way; the other stands on.

Territorial sea

Under UNCLOS, the belt of sea extending 12 nautical miles from the baseline, over which the coastal state exercises sovereignty subject to innocent passage.

MARPOL Annex I limit

Oil discharge is prohibited within 50 nautical miles of the nearest land; beyond that, discharge is allowed only under the 15 ppm and rate conditions.

Fire triangle

The three elements needed for combustion: fuel, oxygen, and heat; removing any one of them extinguishes the fire.

Enclosed space entry

Entry into a space where the atmosphere must be tested for oxygen (19.5–23.5%), hydrocarbons, and toxic gases, with a standby person at the entrance.

SART

A search and rescue transponder that responds to 9 GHz radar signals, displaying a series of dots on the radar screen to help locate the survival craft.

GMDSS sea area A3

A sea area within the coverage of an Inmarsat geostationary satellite, where ships must carry Inmarsat or HF equipment for distress communications.

DSC distress alert

A digital selective calling alert sent on VHF channel 70 or MF/HF 2187.5 kHz containing the MMSI, nature of distress, and position, followed by a voice call.

NAVTEX

A system broadcasting maritime safety information on 518 kHz internationally, received automatically by ships within about 200 nautical miles of the transmitter.