The most important characteristic of a buoy is its colour. When you're traveling upstream, entering a harbour, or moving along a channel toward an area that can be considered more protected, you keep the red buoys on your port or left side... Conversely, the green buoys are passed on your starboard or right side... By convention, the red buoys have even numbers painted on them, and the green ones have odd numbers.

Lateral marks always mark the limits of channels or fairways. They are called starboard and port marks.

• The starboard mark is cone-shaped and is green. It is always kept on the starboard side of the boat when it is traveling upstream.
  
• The port mark is can-shaped and is coloured red. It is always kept on the port side of a boat when it is traveling upstream.

These marks stay in place all the time, so when traveling downstream towards the sea, the marks have to be kept on the opposite sides of the boat. The starboard green cone-shaped mark then is kept on the port side of boat and the port red can-shaped mark is kept on the starboard side.

There are a number of mnemonics to help keep this straight. One simple one is... 'port to port to port'..., meaning that one should keep the port 'wine' coloured (red) mark on the port (left ) side when going into port (PPP)traveling upstream.

Another is... green gauche going...keep the green (starboard) mark on one's left side (gauche is French for 'left' ) when going out of port (GGG)traveling downstream.

port mark is coloured red and the basic shape is a can

starboard mark is coloured green and the basic shape is conical

By night a port buoy shows a red light and a starboard buoy shows a green light (when lit)

Cardinal marks always indicate that there is danger to navigation, and they point out the direction of safe water.

There are four cardinal marks known as North, South, East, and West cardinals. Each cardinal mark tells the skipper which side of it to pass with safety.

• In the case of the North cardinal the boat should pass to the North of it.
• For the South cardinal, pass to the South of it.
• Similarly for East and West cardinals.
  

It is obvious that cardinal marks can't be used effectively unless there is an accurate compass on board the boat, to indicate which side to pass!

A cardinal mark may indicate:

• The deepest water in an area
• The safe side on which to pass a danger and to draw attention to a feature in a channel such as a bend, junction or an end of a shoal.
• Top Marks - black double cones clearly separated.
• Colours - Black and yellow horizontal bands with the position of the black band or bands relative to the respective cardinal points.

For the North cardinal the two cones point upwards following the convention that north on a map is up - black band above yellow band.

For the South cardinal the two cones point downwards following the convention that south on a map is downwards - black band below yellow band.

For the East cardinal the two cones point outwards - apexes apart - black bands above and below yellow band

For the West cardinal the two cones point inwards - apexes together - black band between yellow bands.

The east and west marks are perhaps easier to confuse than the north and south. The following will help.

'E' comes before 'W'. Apexes Apart (AA) comes before Apexes Together (AT)

There are three individual marks in the IALA System, each with its own particular message.

Isolated danger marks

The Isolated Danger mark is used as a warning that immediately below it there is a danger of fairly small dimensions, such as a single rock or the wreck of a small vessel.

Isolated Danger Marks	The mark tells us that it is safe to navigate in any direction around it provided that a good clearance from the mark is maintained. Colour: Black with one or more red horizontal bands. Topmark: Two black balls one on top of the other and clearly separated. Light: A white flashing light showing groups of two flashes. The characteristics may be best remembered by association of....two flashes with two spheres as the topmarks.
Safe Water Marks	Safe water marks They indicate that there is safe water all around, and are usually found at the end of a channel or separation zone to show that hazards are no longer present. At night the Safe Water mark shows a white light with one flash only, followed by a period of darkness. It should not be confused with a North Cardinal mark which has a continuous quick flashing light. Colour: Red and white vertical stripes Topmark: A single red ball Light: Exhibits a white light, isophase, occulting, or single Long flash every 10 seconds... Single flash and a single sphere association may help the characteristics be remembered.
Lights on Special Marks flash yellow.	Special marks They are used for many purposes, such as indicating the presence of underwater cables... prohibited anchorages and areas temporarily closed to water traffic. However, the real message given by a Special Mark is "go and refer to your chart and sailing directions, and find out why I am here". Special marks are used for many different applications and you must refer to other information to understand what function they are performing at any one time. Colour: Yellow Topmark: When a topmark is carried, it takes the form of a single yellow X. Light:It is yellow, the rhythm may be any other than those used for the white lights of cardinal, isolated danger and safe water marks.

Local aids to navigation were mentioned at the start of this chapter, and we pointed out that such aids, prohibition and advisory signs are put in place by the local waterways authorities who monitor and enforce the rules.

Speed limit: 4 knots all round

Speed limits are imposed in some areas for safety reasons and signs indicating the speed limits are generally, but not always, erected on the shore in such areas. It is important to remember that the local rules and regulations apply whether there are signs erected or not. Apart from speed limits, there are signs indicating No Waterskiing, No Anchoring or Beaching, No Wash Zone, Submarine Cables and Naval Waters. Details of signs and their locations may be obtained from the local waterways authorities.