The direction of buoyage
1The lesson in plain words
Lateral colours only make sense with a direction. The conventional direction of buoyage usually runs from seaward, and the chart shows it where it is not obvious.
Why direction matters
A lateral mark says “port side” or “starboard side”, but only for a vessel going one way. That way is the conventional direction of buoyage. Heading in that direction, you leave port-hand marks to port. Heading against that direction, you leave them to starboard. Before you read any lateral mark, know which way the direction of buoyage runs.
From seaward
IALA defines two cases. The first is the general direction a vessel takes when approaching a harbour, river, estuary or other waterway from seaward. On a normal seaward approach, entering follows the direction and leaving reverses it. Check local chart notes. This covers most harbour approaches, and it is what “returning from sea” means in memory aids.
Along coasts
Off open coasts and between channels there is no obvious “from seaward”. There the competent authority, the national body responsible for marks, sets the direction, in agreement with its neighbours where needed. In principle it runs clockwise around land masses. In British waters, for example, it runs north along the west coasts, east through the English Channel and north through the North Sea.
On the chart
Where the direction is not obvious, the chart shows a direction of buoyage symbol: a magenta arrow, with a coloured version on charts printed in several colours. INT 1, the key to chart symbols, lists it in its buoys section. Pilot books and chart notes describe local arrangements, for example in rivers with two entrances.
Numbers on marks
Where lateral marks are numbered or lettered, the numbering follows the direction of buoyage. IALA recommends even numbers on red marks and odd numbers on green marks. That holds in both regions, so in the US, where red is to starboard when entering, the even numbers are on your starboard side.
2Key data
- From seaward
- Direction taken approaching a harbour, river or estuary
- Along coasts
- Set by the authority; in principle clockwise round land masses
- Chart symbol
- Magenta arrow where the direction is not obvious
- Numbering
- Follows the direction of buoyage; even on red, odd on green
3Key points
- 1
Lateral marks mean port or starboard only for a vessel going in the direction of buoyage.
- 2
On a normal seaward approach, entering follows the direction and leaving reverses it. Check local chart notes.
- 3
Along coasts the authority sets it, in principle clockwise round land masses.
- 4
Where it is not obvious, the chart shows a magenta direction of buoyage arrow.
- 5
Numbering follows the direction of buoyage: even on red, odd on green.
4Frequent mistakes
Wrong: Port-hand marks always go to port, whichever way you are going.
Right: That holds only in the direction of buoyage. Going the other way, you leave port-hand marks to starboard.
Wrong: Along a coast the direction always points towards the nearest harbour.
Right: Along coasts the authority sets it, in principle clockwise round land masses. Check the arrow on the chart.
Wrong: Buoy numbers tell you nothing about the direction of buoyage.
Right: Numbering follows the direction of buoyage, so the sequence on the chart confirms which way it runs.
5Practice case & exam keys
You are leaving a Region A waterway. The chart’s buoyage arrow points the same way as your track. A crew member says, “Outbound means red to starboard.” Do you agree? On which side of your boat should you leave red port-hand marks?
Show the answer
No. Here you are travelling with the charted direction of buoyage, so leave red port-hand marks to port. Use the charted direction, rather than the word outbound, to decide the passing side.
Exam keys
- Direction of buoyage: from seaward into harbours, rivers and estuaries.
- Along coasts: set by the authority, in principle clockwise round land masses.
- The chart shows a magenta arrow where the direction is not obvious.
- Reverse passing sides when travelling against the charted direction of buoyage.
Finish this unit
When you've read it, match the terms, then answer three questions. Get them all right to finish the unit; opening the page alone doesn't count.
My notes for this unit
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