HK Coxswain Grade 3 key terms

Buoyage system used in Hong Kong waters where red can buoys mark the port side and green conical buoys mark the starboard side of a channel when entering from seaward.

Buoys indicating the safe side on which to pass by pointing to the compass quadrant where deep water lies, using combinations of two cones and distinctive black and yellow colours.

A black buoy with a red horizontal band and two black spheres on top, placed over a small isolated hazard surrounded by navigable water on all sides.

A red and white vertically striped buoy with a single red sphere, marking the centre of a navigable channel or the approach to a harbour or fairway.

Two fixed lights aligned vertically, showing different characteristics, which a vessel keeps in line to steer a safe course through a channel or harbour entrance.

A position line obtained by observing two charted objects, such as leading lights or two headlands, in line, confirming the vessel lies on the line joining them.

A position fix plotted from the intersection of two or more position lines taken by compass bearing on charted landmarks, corrected for compass error.

The low-water reference level to which depths printed on a nautical chart are reduced, so that actual depth is charted depth plus the height of tide.

The vertical distance of the sea surface above chart datum at a given time, found from tide tables and used to convert charted depths into actual depths.

The margin of water between the lowest point of a vessel's hull and the seabed, calculated from charted depth, tide height and vessel draught, allowing for squat and swell.

The reduction in under-keel clearance and change of trim experienced by a vessel moving through shallow water, increasing with speed and becoming significant in confined channels.

The tendency of a vessel in a narrow channel to be drawn towards the nearer bank and to shear, caused by pressure differences in the water flow around the hull.

The mutual hydrodynamic effect between vessels passing close to each other, producing suction and course changes, strongest when overtaking in confined or shallow water.

The COLREGs requirement to maintain a lookout by sight and hearing, and by all available means, at all times, so as to make a full appraisal of the situation and risk of collision.

A situation where a vessel's approach to another creates doubt about safety; if the bearing of an approaching vessel does not appreciably change, such risk shall be deemed to exist.

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

In a crossing situation, the vessel with the other on her own starboard side, which must keep out of the way and, where possible, avoid crossing ahead of the stand-on vessel.

The vessel that must keep her course and speed when another is give-way, but may take action to avoid collision as soon as it becomes apparent the give-way vessel is not acting.

The COLREGs provision requiring vessels to keep as near to the outer limit of a narrow channel on their starboard side as is safe and practicable, and not to cross it unnecessarily.

Any vessel approaching another from more than 22.5 degrees abaft her beam; she must keep out of the way until finally past and clear, regardless of what the other vessel is doing.

Conditions such as fog, mist, falling snow or heavy rain that reduce visibility; vessels must proceed at a safe speed, sound fog signals and, for power-driven vessels, have engines ready for immediate manoeuvre.

The sound signal prescribed in restricted visibility, such as one prolonged blast at intervals for a power-driven vessel making way, used to warn other vessels of presence and movement.

Names for ropes securing a vessel, including head line, stern line, breast line and spring, each controlling a different direction of movement alongside a berth or pontoon.

A mooring rope led fore and aft from the vessel to the shore or pontoon to prevent the boat from moving ahead or astern along the berth.

A stern-to mooring technique in which the vessel lies with her stern close to a quay, held by lines to the shore and often by an anchor laid out ahead.

The point about which a vessel turns when the rudder is applied; when moving ahead it lies ahead of midships, and when going astern it moves aft of midships.

The sideways force produced by a propeller, especially when going astern, which can swing the stern to port or starboard depending on the propeller's rotation direction.

The tendency of a vessel's stern to swing to one side because of the asymmetric thrust of a right- or left-handed propeller, most noticeable when manoeuvring at slow speed.

The numbered signals 1, 3, 8, 9 and 10 issued by the Hong Kong Observatory to warn of tropical cyclones, with signal 8 indicating gale or storm force winds expected or prevailing.

The seasonal wind pattern affecting Hong Kong, with the northeast monsoon bringing cooler, drier and often stronger winds in winter and the southwest monsoon bringing warm, humid, unsettled weather in summer.

A sudden, sharp increase in wind speed, often with a change of direction and heavy rain, associated with thunderstorms or the passage of weather systems and dangerous to small craft.

A local diurnal wind that blows from the sea towards the land during the day and reverses at night, caused by differential heating of land and water and relevant to afternoon conditions in Hong Kong.

The spoken distress signal used by radiotelephone to indicate that a vessel or person is in grave and imminent danger and requires immediate assistance, sent on VHF channel 16.

The urgency signal used by radiotelephone to announce a message concerning the safety of a vessel or person that is not yet in grave and imminent danger.

Internationally recognised signals indicating distress, including red parachute flares, orange smoke, SOS by any means, and arms raised and lowered slowly, listed in the COLREGs annex.

The three elements needed for combustion: fuel, heat and oxygen; firefighting acts by removing one or more of these, for example by closing fuel valves or using a fire blanket.

Fires involving flammable liquids such as petrol, diesel or oil; on small craft they are fought with foam, dry powder or carbon dioxide, never with water.

A practised procedure for leaving a vessel in an emergency, covering the signal to abandon, donning lifejackets, mustering, launching survival craft and accounting for all persons.

A personal flotation device designed to keep an unconscious or exhausted person's head above water and turn them face-up; one must be provided for every person on board.

The international convention annex regulating prevention of pollution by oil, prohibiting discharge of oily mixtures into the sea and requiring oily water to be retained and landed ashore.

The annex controlling pollution by garbage from ships, prohibiting disposal of plastics into the sea and restricting discharge of other waste according to distance from land.

A documented procedure for collecting, storing, processing and disposing of shipboard waste, required for larger vessels and good practice for small craft to prevent marine pollution.

The Hong Kong licence issued by the Marine Department to a person who has met the examination and experience requirements to act as coxswain of a specified class of local craft.

The document issued by the Marine Department recording the owner of a licensed local craft, required for registration and transfer of ownership.

The Marine Department licence permitting a local craft to be used for a stated purpose and within stated limits, subject to conditions on area of operation and manning.

Local rules limiting where and how craft may operate, including speed limits in specified areas, prohibited zones near beaches and fairways, and requirements to report to the Marine Department.