Boat Notes - Literacy and Numeracy Skills for Maritime Training

12 hour time: 12 hour time breaks a day up into two 12 hour parts. Am is the morning from midnight to midday and pm is the afternoon from midday to midnight.
24 hour time: 24 hour time tells the time over 24 hours in a day from 0000 to 2359. The first two digits are the hours and the second two digits are the minutes.
alternating light: An alternating light changes from one colour to another.
Australian Hydrographic Service: The Australian Hydrographic Service make marine charts in Australia.
bearing: Bearing is the direction of a landmark from a boat.
Beaufort scale: A scale to describe the speed and effects of wind.
cardinal mark: Cardinal marks show the direction of safe water.
cardinal points: The cardinal Points North East South West are used to give directions.
chart datum: The lowest possible tide for an area. Depths on a chart are measured from chart datum.
chart scale: Chart scale is on the sides of a marine chart. Chart scale is used to find coordinates, plot position and measure distance.
charted depth: Depth of the water written on a marine chart. This is the depth on the lowest astronomical tide for that area.
cold front: The leading edge of cool air pushing under warm air creating storms, wind and rain.
compass error: Compass error is change to a compass reading caused by the earths magnetic field (variation) or magnetic objects near a compass (deviation).
compass rose: A circle used to show direction with degrees or cardinal points.
contour lines: Contour lines are lines of the same water depth shown on a marine chart. On land, contour lines show the same elevation.
coordinate: A coordinate locates a position on a grid.
course: A course is a direction or path that you want a boat to travel.
course over ground: Course over ground is the course in degrees over the ocean floor that you want you boat to travel.
course to steer: The course to steer is a true course from a chart adjusted for compass error. It is the course in degrees to steer on your compass.
decimal: A decimal number is broken into tenths, hundredths, thousandths etc.
degree: Degrees are used to measure angles, give direction and plot coordinates on a chart.
degrees: Degrees are used to give direction, there are 360 degrees in a circle.
diurnal tide: A diurnal tide has one high and one low tide in a day.
draft: Draft is the depth of the hull in the water.
drying area: An area that covers and uncovers with the tide.
drying height: Drying height is the height above the lowest tide when a rock sandbar or mudflat dries. Shown on a marine chart with an underlined number.
elevation: Elevation is the height of a landmark above high tide.
equator: The Equator is the line of latitude at 0°. Latitude is measured North or South of the Equator.
fetch: Fetch is the distance the wind has blown over water. Longer fetch makes bigger waves.
fix: A fix uses compass bearings to plot your position on a chart.
fixed light: A fixed light is always on.
flashing light: A flashing light has dark longer than light.
fraction: A fraction is part of a whole e.g. half.
fuel consumption: Marine fuel consumption is measured in litres per hour.
gauge: A gauge is an instrument that measures and gives a display of the amount, level, or contents of something. E.g. a fuel gauge.
gravity: Gravity is the force that pulls toward the centre of the earth or moon.
ground track: The ground track is path over the ocean floor that your boat travels.
Heading: Heading is direction the boat is pointing.
hectopascals: A hectopascal is a unit of measurement for air pressure.
high pressure system: A high pressure system is an area of high pressure that rotates anti-clockwise in the southern hemisphere.
horizontal: Horizontal means flat or across.
isobar: An isobar is a line of equal pressure draw on a synoptic chart.
isolated danger mark: A red and black marker used to show a danger on its own.
isophase light: An isophase light has light and dark the same length of time.
knots: Knots are the marine measurement of speed. One knot is one nautical mile per hour.
lateral marks: Lateral marks are green or red markers that show channels of deeper water.
latitude: Latitude and longitude make an imaginary grid over the earth. Lines of latitude run horizontally. Lat is flat.
leg: A leg is a path between two waypoints.
longitude: Latitude and longitude make an imaginary grid over the earth. Lines of longitude run up and down from pole to pole.
low pressure system: A low pressure system is an area of low pressure that rotates clockwise in the southern hemisphere.
lowest astronomical tide: The lowest possible tide for an area.
magnetic deviation: Magnetic Deviation is compass error caused by metal, magnets or objects near a compass.
magnetic north: Magnetic north is made by the earths magnetic field. It is different to true north.
magnetic variation: Magnetic variation is compass error caused by the earths magnetic field.
marine chart: A marine chart is a map used to navigate on the ocean.
minute: A minute is 1/60th of a degree. A minute can also mean 1/60th of an Hour.
mixed tide: A mixed tide is in between a diurnal and semidiurnal tide.
monsoon trough: The monsoon trough is a seasonal trough that forms over northern Australia in the wet season creating heavy rain, storms and sometimes cyclones.
nautical mile: Nautical miles are used to measure distance on the ocean. A nautical mile is one minute of latitude or 1.85 km.
neap tide: A neap tide is a tide just after the first or third quarters of the moon when there is least difference between high and low water.
notices to mariners: Notices to Mariners show changes to a marine chart.
occulting light: An occulting light has light longer than the dark.
percent: Percent is a fraction out of 100.
port: Port is the left side of the boat when facing forward.
port hand mark: A port hand mark is a red lateral mark kept to port when travelling upstream.
position: Position is the location of a boat given as a coordinate or distance and direction from a landmark.
prime meridian: Line of longitude at 0° at Greenwich, England. Longitude is measured east or west of the Prime Meridian.
range (light): The range is the distance when a light can be seen in clear visibility.
safe water mark: A red and white marker showing safe water or the entrance to a marked channel.
seas: Seas are waves caused by local winds.
semi-diurnal tide: A semidiurnal tide has two high and two low tides in a day.
special mark: A special mark is a marker for different reasons such as a pearling lease, aquaculture, yacht racing area and so on.
spring tide: A spring tide is a tide just after a new or full moon, when there is the greatest difference between high and low water.
starboard: Starboard is the right side of the boat when facing forward.
starboard hand mark: A starboard hand mark is a green lateral mark kept to starboard when travelling upstream.
swell: Swell is waves made by distant storms that travel from a long distance away.
synoptic chart: A synoptic chart is a map of pressure difference and weather systems at sea level.
title block: The title block shows the name and location of the chart.
trough: A trough is a line of low pressure creating winds and unsettled stormy weather. A trough can also mean the low point between two waves.
true north: True north is at the North Pole. True north is up on a marine chart.
under keel clearance: Under keel clearance is the distance between the hull of a boat and the ocean floor.
volume: Volume is the amount of something that a container can hold e.g. the fuel tanks has a volume of 25 litres.
warm front: The leading edge of warm air pushing over cool air creating rain and wind.
waypoint: A waypoint is a point on a course.
whole number: A number without a decimal point.