ADVANCED PB GLOSSARY

AIS

Automatic Identification System

Almanac

Information about ports & harbours including tidal heights, curves. Published annually

Anticyclone

High pressure weather system

AVS

Angle of vanishing stability. Angle from the vertical beyond which a craft will no longer return upright but will capsize

Back Bearing

A bearing taken astern of a crest (using hand held bearing compass) to a feature to ensure vessel stays on intended track

Bearing

Direction of one object from another

Beaufort sale

International scale of wind speed and wave height

Broaching

When a vessel becomes broadside to a wave and is rolled onto its side

Bucket

Deflector used on jet drives to redirect water flow

Chart Datum

The vertical level to which charts are drawn representing the lowest astronomical tides (LAT)

Chartplotter

Electronic chart system

Clearing lines / ranges

Position lines/range to clear hazards on charts / chart plotters

COLREGS

Collision regulations - International regulations preventing collisions at sea

Compass Rose

Representing of compass card on chart

Contour Lines

Lines on a chart linking points of equal depth

COG (Course over ground)

The course a craft is processing along although the craft may not be pointing in the direction

Crabbing

Moving sideways without any ahead or astern movement

Cross Bearing

Bearing to port or starboard

Day shapes

Shapes or cones (combinations of) to indicate why vessels movement may be constrained

Dead reckoning

Position based on time distance and direction traveled though water from know position

Deflector

Used on jet drives to redirect water flow

Depression

Low pressure weather system

Deviation

Compass error caused by presence of electromagnetic fields or ferrous objects (iron or alloys containing a high percentage of iron)

Displacement hull

Traditional shape hull where craft moves through (displaces)

DSC

Digital selective calling system, part of a VHF radio

EBL

Electronic bearing line. Found on radar to measure bearing s to an object

EPRIB

Emergancy position indicating radio beacon

Ergonomics

Study if efficiency of persons in working environment such as how instruments and controls and laid out at the helm.

Estimated position

Dead reckoning but with total steam adding in to

Ferry gliding

Technique for moving a craft sidewise balances steam or wind, the angle of the credit and ahead or astern throttle

Forward-facing drive

Pivoting drive system through hull of craft with propellers facing forwards

Free surface effect

Loss of stability of vessel resulting from water in bilges or on deck that is unable to drain rapidly

GNSS

Global Navigation Satellite System

Ground Track

Direction the craft is actually moving over surface of the earth

Head Bearing

A bearing taken ahead of a cradt using a hand bearing compass to a feature to ensure vessel stays on intended track

Heading

Direction in which the vessel is actually pointing at any given time

Helm

Stearing positon H

Horizontal chart datum

The datum the chart is drawn to E.G WGS84

IMO

International Maritime Organisation

Impeller

Propeller encased in a jet drive unit

Jet Drive

Water pumped through a steerable nozzle to create thrust and turn a craft

Jockey Seat

Astride seats

Latitude

lines bisecting the earth horizontal expressed as an angle relative to equator and measured in degrees and minutes

Leeway

Effect of wind on vessel pushing it away from intended track

Longitude

Horizontal lines between poles referred to as east or west off the prime meridian - measured in degrees and minutes

MARPA

Mini automatic radar plotting aid

MARPOL

International Convention for the prevention of pollution from ships

MMSI

Maritime mobile service identity - unique number

MRCCs

Maritime rescue co-ordinations centres

Mullions

Vertical bars between the windows in a vessels cabin

NDP

Nominated departure point for vessels operator license

Neap tides

Where the sun & moon act at right angles to the earth leading to more moderate high and low tides

Outdrive

Drive system through stern

Paddlewheel effect

Propwalk

Pilotage

Navigation of vessel within close proximity to land visible object

Pivot points

Point in the craft about which it pivots - varies between astern and forward

Planning hull

When gaining speed enable the cradt to travel on the surface of the water

Propwalking

Sideways movement of stern caused by rotation of propeller in reverse

Raster Chart

Direct electronic copy or scan of existing paper chart

Rule of Twelfths

Mathematical process for estimating heights of the rides at given the time between high and low waters

Safe Haven

A place that a vessel cpu;d see setter in poor conditions. A term relevant to the licensing of commercial craft

Secondary ports

Smaller ports which don’t have their own tidal curve in an almanac. An adjustment process is used to utilise a tidal curve from a standard port

Semi Displacement Hull

Hull shape combining benefits of displacement and planing type

Shaft-drives

Drive systems for inboard engines entitling a shaft rotating the propeller and rudder for steerage

SOLAS

Convention for the safety of life at sea

SOG - Speed Over Ground

The actual speed a craft is achieving after stream and wind have been factored in

Spring tides

Where the sun and moon act together to produce higher high tides and lower low tides

Springs

Morning lines running diagonally from boat to berth to arrest / limit forward/astern movement of the craft

Standard Ports

Lager ports that appear in almanacs with their own tidal curves and tidal data

Stream

Movement if water caused by tide or river flow

Strum box

Strainer on the bilge end of the build pump pipe

Stuffing

In a following sea a craft is driven over a wave and ploughs into back of the next one

Synoptic charts

Weather charts given a general view of weather conditions

Thruster - bow & stern

Bow & stern thrusters

Tidal Streams

Horizontal movement of tides

Tidal Vector

Line drawn on a chart representing direction and flow of tide

Transit

Line up two points either to native along or to establish position with

Trim

Changing the boats attitude for the best safety comfort and consumption and handling

TRIM TABS

Mechanical driven plates mounted either side or stern to adjust to trim

TSS

Traffic Separation Scheme

UNCLOG

United Nations convention of the law of the sea

Variation

Difference between magnetic north and true north

Vector Chart

Digitised version of a paper chart with ability to select/hide some information

VRM

Variable range marker. Found on Radar often used to measure distance to object

Waypoints

GNSS position storage

WGS84

World geodetic system 1984 datum standard

Williamson turn

Method of turning to return along vessels own wakeWind

Windage

Wind resistance of the side area of boat

XTE

Cross tract error - known as off course distance to one Side of the exact tract between two waypoints