MAJ OOW Deck Exam 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 in nautical miles equals 60 times the arccos of (sin lat1 sin lat2 + cos lat1 cos lat2 cos DLo). Used for ocean passages between two positions.

Sextant index error

The error of the sextant's zero reading, found by bringing the horizon into coincidence with its mirror image. Applied with sign to every observed altitude before other corrections.

Cocked hat uncertainty

The small triangle formed when three position lines fail to intersect at one point. Its size indicates the random error of the observations, not a systematic error.

RAIM in GPS

Receiver Autonomous Integrity Monitoring. The receiver uses redundant satellites to detect a faulty signal and warns the navigator, essential for harbour approaches and ECDIS fixes.

Rule 13 overtaking

Any vessel overtaking another keeps clear until finally past and clear. When in doubt whether overtaking, assume it is, and never rely on the overtaken vessel's actions.

Rule 19 restricted visibility

In fog no vessel has right of way. Reduce to safe speed, take avoiding action in ample time, and avoid turning to port for a vessel forward of the beam.

Safe speed factors

Rule 6 requires consideration of visibility, traffic density, manoeuvrability, stopping distance, background light, wind and sea state, and draft relative to available water.

Buys Ballot's law

With your back to the wind in the Northern Hemisphere, low pressure lies to your left. Reverse the rule in the Southern Hemisphere to locate the depression centre.

Advection fog

Forms when warm moist air moves over a colder sea surface and is cooled below its dew point. Requires wind, so it is common in spring and summer over cold currents.

Right-hand semicircle

The dangerous semicircle of a Northern Hemisphere tropical storm, where the wind blows towards the storm track. Vessels should steer to put the wind on the starboard bow.

Collision bulkhead position

Fitted between 5% LOA or 3 m (whichever is greater) and 8% LOA from the forward perpendicular, to limit flooding in a head-on collision.

Load line freeboard deck

The uppermost continuous deck with permanent means of closing all openings. The load line marks are measured downward from this deck at midships.

Cofferdam purpose

A void space between two tanks or bulkheads that isolates incompatible cargoes or prevents leakage between them. Typically 0.6 to 1.2 m wide.

Metacentric height GM

GM equals KM minus KG. Positive GM gives a stable ship; negative GM causes an angle of loll. Typical loaded cargo ship GM is 0.15 to 0.30 m.

Free surface correction

FSC equals the second moment of area of the free surface times liquid density divided by displacement. It reduces effective GM and is larger in wide, shallow tanks.

Moment to change trim

MCTC is the moment needed to change trim by one centimetre. Change of trim equals weight moved times distance moved, divided by MCTC.

Angle of loll correction

A ship with negative GM lolls to either side. Correct by lowering weights or filling low centreline tanks; never shift weight to the high side, which may capsize her.

Clean bill of lading

A bill of lading bearing no adverse remarks about the apparent order and condition of the goods. It is prima facie evidence of shipment in good condition.

Hague-Visby package limit

Liability is capped at 666.67 SDR per package or 2 SDR per kilogram, whichever is higher, unless the shipper has declared the nature and value.

Cargo sweat ventilation

Ventilate only when the dew point of outside air is lower than the dew point of the cargo space, otherwise moisture condenses on the cargo and damages it.

Steering gear SOLAS test

Main steering gear must move the rudder from 35 degrees one side to 35 degrees the other in 28 seconds at maximum ahead service speed, with two independent power units.

Emergency generator timing

Must start automatically and take load within 45 seconds of a blackout, supplying emergency lighting, navigation lights and radio for at least 18 hours.

Fuel oil viscosity control

Fuel is heated to reach 10 to 15 cSt at the injector, controlled by a viscosimeter. Settling, purification and clarification remove water and solids first.

Abandon ship signal

Seven short blasts followed by one prolonged blast on the ship's whistle. The order to abandon is given only by the master after all alternatives are exhausted.

Williamson turn

Man overboard manoeuvre: put the helm hard over, then reverse it after about 60 degrees of turn, to return on a reciprocal track close to the casualty.

Fire classes and media

A solids use water; B liquids use foam, CO2 or powder; C gases use powder and shut off supply; D metals use special powder; F cooking oil uses wet chemical.

CO2 fixed system release

Two-stage alarm and delay precede release. The space must be sealed, ventilation stopped and all persons accounted for, or the release will be fatal.

Immersion suit standard

Must be provided for every person on board and allow the wearer to climb a vertical ladder and jump from at least 4.5 m without injury.

MARPOL Annex I limits

Oil discharge is prohibited within 50 nm of land. Outside that, discharge must be below 15 ppm and at no more than 30 litres per nautical mile.

Annex VI sulphur limits

Global sulphur limit is 0.50% m/m since 1 January 2020. Emission control areas require 0.10% m/m, met by low-sulphur fuel or an approved scrubber.

STCW rest hours

Minimum 10 hours rest in any 24-hour period and 77 hours in any 7-day period. Rest may be split into at most two periods, one at least 6 hours.

GMDSS sea areas

A1 is VHF DSC coverage, A2 MF, A3 HF or Inmarsat, A4 HF outside all other areas. The ship carries equipment appropriate to the area it operates in.