Hong Kong Part A Written Test key terms

The vessel required to keep out of the way of another under the Collision Regulations. It must take early and substantial action, and normally passes astern of the stand-on vessel.

The vessel that keeps its course and speed when risk of collision exists. It must still act if the give-way vessel fails to comply, and may sound warning signals.

A situation where the bearing of an approaching vessel does not appreciably change as range decreases. If in doubt, such risk is deemed to exist and action must be taken.

The speed at which a vessel can take proper and effective action to stop within a distance appropriate to the prevailing circumstances, including visibility, traffic density and manoeuvrability.

Two power-driven vessels approaching on converging courses with risk of collision, neither head-on nor overtaking. The vessel with the other on its starboard side keeps out of the way.

Two power-driven vessels meeting on nearly reciprocal courses with risk of collision. Both alter course to starboard and pass port side to port side.

A vessel approaching another from more than 22.5 degrees abaft its beam, or in a position to see only its stern light. It must keep clear until finally past and clear.

A restricted waterway where a vessel must keep as near to the outer limit on its starboard side as is safe and practicable, and avoid crossing if it impedes larger traffic.

A routing system using separation zones, lanes and inshore traffic zones to reduce collision risk. Vessels must proceed in the general direction of traffic flow in a lane.

Short or prolonged blasts from a whistle used to indicate manoeuvres, warnings or restricted visibility. One short means altering to starboard; five short blasts means doubt or danger.

Conditions such as fog, heavy rain or smoke that reduce visibility. Vessels must proceed at a safe speed, sound fog signals and have engines ready for immediate manoeuvre.

A sound signal sounded in restricted visibility to warn other vessels of presence and type. Power-driven vessels underway make one prolonged blast at intervals of not more than two minutes.

Hong Kong-specific requirements supplementing the international regulations, covering matters such as local speed limits, ferry routes and signals in the harbour and approaches.

A navigation light showing red on the port side and green on the starboard side, visible over an arc from dead ahead to 22.5 degrees abaft the beam on each side.

A white light placed over the fore-and-aft centreline showing an unbroken arc of 225 degrees, from dead ahead to 22.5 degrees abaft the beam on either side.

A white light placed near the stern showing an unbroken arc of 135 degrees, visible from dead astern to 67.5 degrees on each side, indicating a vessel's direction of travel.

A lamp fitted to a vessel to show its type, size and aspect at night. Correct display, screening and arc of visibility allow other vessels to determine course and role.

The direction of an object from the observer, measured in degrees clockwise from a reference such as true north. Repeated bearings reveal whether risk of collision exists.

A bearing taken with a magnetic compass, which must be corrected for variation and deviation to convert it to a true bearing for plotting on a chart.

The angle between true north and magnetic north at a given place and time, shown on the chart and changing slowly from year to year as magnetic fields shift.

The error of a magnetic compass caused by the vessel's own magnetic fields and metalwork. It varies with heading and must be recorded on a deviation card.

The confirmed location of a vessel obtained by intersecting two or more position lines, such as bearings, ranges or GPS readings, plotted on a chart.

An estimated position found by advancing the last known fix using course steered, speed and elapsed time, without reference to external landmarks or electronic aids.

The best guess of a vessel's position, derived from dead reckoning adjusted for known factors such as tidal stream, current and leeway.

The sideways drift of a vessel downwind of its steered course, caused by wind and wave action on the hull and superstructure. It must be allowed for when plotting.

The reference level from which depths on a nautical chart are measured, usually close to lowest astronomical tide so that charted depths are mostly greater than actual depths.

The horizontal movement of water caused by tides, with a set and a rate. It must be added to a vessel's course and speed to find the course made good.

The predicted or observed vertical level of the sea at a place and time, obtained from tide tables and referenced to chart datum for depth calculations.

The vertical distance between the lowest point of a vessel's hull and the seabed. It is found by adding charted depth and tidal height, then subtracting draught.

The vertical distance from the waterline to the lowest point of a vessel's hull. It determines the minimum depth of water the vessel can safely navigate.

The reduction in under keel clearance and change of trim experienced by a vessel moving through shallow water, caused by the interaction of hull and seabed.

A system of marks indicating the sides of a navigable channel. Region A uses red to port and green to starboard when entering from seaward, with shapes matching colours.

A buoy or beacon indicating the safe side on which to pass, named by compass direction. Its topmarks and light rhythm tell the mariner where the danger lies.

A mark showing navigable water all around it, often at a channel entrance or landfall. It has red and white vertical stripes, a single red sphere topmark and a white light.

A mark placed on or near a small isolated hazard with navigable water around it. It is black with red bands and carries two black spheres as a topmark.

The international body that standardises aids to navigation worldwide. Its system divides regions into A and B, differing in the colours used for lateral marks.

A scale from 0 to 12 describing wind strength by its observable effects at sea, such as wave height and the behaviour of smoke, foam and vessel motion.

A description of the condition of the sea surface, combining wave height, period and roughness. It is reported in forecasts and affects safe speed and vessel handling.

A sudden, brief increase in wind speed, often with rain and a rapid veer or shift in direction. It can arrive quickly in Hong Kong waters during the summer months.

A numbered warning issued in Hong Kong by the Observatory to indicate tropical cyclone strength and expected wind speeds, ranging from Signal 1 to Signal 10.

An abnormal rise in sea level caused by a tropical cyclone, added to normal tide. It can flood low-lying coastal areas and reduce bridge and overhead clearances.

The spoken distress signal used on VHF radio when a vessel or person is in grave and imminent danger and requires immediate assistance. It has absolute priority.

The spoken urgency signal used when a vessel or person is in difficulty but not in immediate danger, such as engine failure without risk to life.

The international distress, safety and calling frequency at 156.8 MHz. It is monitored continuously for Mayday and Pan-pan traffic and used only for initial contact.

A transmitted message, often digital via DSC, indicating that a vessel needs immediate help. It should include position, nature of distress and number of persons aboard.

An emergency in which a person has fallen into the water. The immediate response is to shout, throw buoyancy, mark the position and manoeuvre the vessel to recover the person.

A ring-shaped flotation device kept ready for throwing to a person in the water. It is often fitted with a light and smoke signal for night or rough conditions.

A personal flotation device worn by each person aboard, designed to keep the head above water. It must be the correct size and checked before every trip.

The boundary defining Hong Kong's harbour and port waters, within which specific regulations, speed limits and reporting requirements apply to vessels.

Rules made for the management and safety of Hong Kong port waters, covering vessel movements, mooring, pollution prevention and reporting obligations.

A maximum permitted speed set for particular Hong Kong waters or vessel types. It is often defined in knots and may be reduced in restricted zones or poor visibility.

A person holding the appropriate Hong Kong licence to operate a specified class of vessel in local waters, subject to conditions and competency requirements.

The statutory items a vessel must carry, such as lifejackets, fire extinguishers, anchor and line, first aid kit and signalling gear, according to its size and use.