Buoyage Systems for Coastal Navigation.

IALA Buoyage Systems.

Lateral Marks

Lateral marks are those which indicate the edge of a safe water channel.

The direction of buoyage dictates how these are set.

The direction of buoyage for all areas covered by the IALA is always is always set in an upstream direction.

The direction is always from the open sea into a harbor, estuary, bay or whatever.

Where there might be any confusion, it will be labeled on the appropriate chart and may be clarified with a cardinal mark.

While the color of the lateral marks may differ across the two region the shape across both remains the same.

In both regions the port hand lateral marks are square (cans) or have a flat top.

The starboard hand marks are conical or triangular in shape and have a pointed top.

These lateral marks may also display identification markings or names and distinctive light identification signals.

These will indicated on your marine chart.

Preferred Channel marks are a modification of the standard lateral mark.

They usually indicate a deep water channel, suitable for heavy commercial traffic, with a secondary channel suitable for shallower draught vessels to the side.

These are identified by a colored (red or green) horizontal stripe.

All the other buoys in the IALA system are the same regardless of which region they are in.

Cardinal Marks.

Cardinal marks are common to all buoyage systems.
They indicate the safe or deepest water side of a hazard.

The cardinal mark's name tells us which side the deepest water lies.

For instance, one should always pass to the north of a North Cardinal mark as the deepest water lies in a 45 degrees quadrant to its north.

And stay to the east of the East Cardinal, south of the South Cardinal and west of the West Cardinal.

Each mark is distinguished by the pattern of its horizontal yellow and black stripes, the arrangement of the top-marks and light signals.

There are several tricks you can use to remember their characteristic identifiers.

Perhaps the easiest to remember and the most important is the flashing light sequence, at night it will be the only one visible.

If you think of the diagram above in term of a clock face, north is at 12 o'clock, east at 3, south at 6 and west at 9.

The east cardinal (at three o'clock) flashes in groups of 3 separated with a blackout.

The southerly flashes in groups of 6, the west cardinal flashes in groups of 9 while the northerly mark flashes continuously.

The speed of the flashing can be either (Q) quick, or (VQ) fast flashing, this will be indicated on your chart..

A (Q) flashing light has 50/60 flashes per minute while a (VQ) light has 100/120 flashes per minute.

They all flash a white light.

During the day the cardinals can be identified by the arrangement of the black and yellow stripes and the black, cone shaped top-marks.

The arrangement of cones at the top is an indication of the black stripe (or stripes) position on the buoy.

The north cardinal has both cones pointing up and the black stripe is always at the top.

The south cardinal has both cones pointing down and the black stripe is at the bottom.

The westerly mark has the cones pointing towards each other so it appears the have a narrow waist (waisted woman of the west has a black belt).

And there is a black stripe across the middle of the mark.

The east is opposite with the cones pointing away from each other and the black stripes are at the top and bottom.

It is reasonable easy to remember the different cone shapes, however it is worth the effort to remember the color codes as these are much easier to distinguish at a distance.

Isolated Danger Mark.

Buoyage marks Isolated danger marks are also common across both IALA regions.

They indicate that there is a hazard directly below the mark, such as a wreck.

These are usually isolated dangers around which the water is safe to navigate.

They are easy to identify with their horizontal black and red stripes.

The top-marks are two black spheres one above the other.

They also have a white flashing light signal but in groups of 2, Fl(2) with a black out between.

Safe water Mark.

The safe water mark is the only one with vertical stripes.

The stripes are red and white and it will also have a red sphere as the top-mark.

They indicate that water is safe for navigation all around the mark.

They may be used to mark fairway approaches or forks in a chanel.

When fitted with a light it is usually white however it may be isophase, occulting (rhythmic flashes of equal length where the period of light is longer than the dark) or flashing the Morse code letter "A".(dot dash).

Special Marks.

The IALA buoyage system also includes the special marks.

They are not so much navigational aids as indicators of special areas or objects mentioned on the charts or other nautical and publications.

They can be of any shape but are always painted yellow and have a yellow light which will be distinctive from other lights in the area.

The top-mark is optional but is usually a yellow X.

Transit or Range Markers.

Range or transit markers are often found on waterways with particularly shallow patches and or with cross currents.

They do not come under the IALA system of buoyage and so can be anything from a couple of withes (simple poles) to a set of lights.

They are always found as a pair with one higher than the other.

They are there to help you to keep to the center line of a channel.

The back marker is always higher than the front one.

The idea is keep the two in line while in the channel.

To keep the pair in line always steer towards the lower front marker.

You also need to watch for the normal buoyage marker which signals the end of that stretch of the channel where you will need to turn.

Sector Lights.

Sector Lights as with range markers are designed to help keep you in a safe navigational area.

The light emitted from a single position will show up as either red, white or green depending on the angle.

Every light is set up specifically for that particular area but its specifics will be clearly marked on the chart.

Depending on the color of the light that he can see the navigator can tell which sector he is in.

Like the range markers they indicate the safe area of a channel or confined waterway but as with range markers they cannot indicate where the channel ends.

So, you also need to watch out for other buoyage marks and refer to your chart.

View my Flipboard Magazine.

• Passage planning
• Pilotage
• Rule of Twelfths

"An incorrectly identified mark is a hazard,
not an aid, to navigation"
(Alton B. Moody)