Study sheet
The IALA Maritime Buoyage System — laterals in both regions, preferred channels, cardinals, and the rest of the family. Original teaching content; system facts verified against IALA/NGA/Trinity House guidance.
Buoyage region
Region A. Identify this mark and say how you pass it, entering from sea.
Port-hand lateral, Region A — red, can-shaped (or pillar/spar with a red can topmark). Entering with the conventional direction of buoyage, leave her to PORT. Light, if any: red, any rhythm other than the preferred-channel Fl(2+1).
Region A. Identify this mark and say how you pass it, entering from sea.
Starboard-hand lateral, Region A — green, conical (or pillar/spar with a green cone topmark, point up). Entering from sea, leave her to STARBOARD.
Region A. The channel divides ahead. Identify this mark — which channel is preferred?
Preferred channel to STARBOARD, Region A — red with one green horizontal band, can-shaped, red Fl(2+1). Treat her as a port-hand mark: take the preferred channel by leaving her to PORT.
Region A. The channel divides ahead. Identify this mark — which channel is preferred?
Preferred channel to PORT, Region A — green with one red horizontal band, conical, green Fl(2+1). Treat her as a starboard-hand mark: take the preferred channel by leaving her to STARBOARD.
Identify this mark. Where is the safe water?
North cardinal — both cones point UP; black band ABOVE yellow (the cones point at the black). Pass to the NORTH of her. Light: white, continuous VQ or Q — the one that doesn't fit the clock face.
Identify this mark. Where is the safe water?
East cardinal — cones point APART (bases together); black bands above and below yellow. Pass to the EAST of her. Light: white, 3 flashes — 3 o'clock on the clock face.
Identify this mark. Where is the safe water?
South cardinal — both cones point DOWN; black band BELOW yellow. Pass to the SOUTH of her. Light: white, 6 flashes + a long flash (the long flash keeps the count unmistakable) — 6 o'clock.
Identify this mark. Where is the safe water?
West cardinal — cones point TOGETHER (a wineglass, W-for-waist); black band between yellow. Pass to the WEST of her. Light: white, 9 flashes — 9 o'clock.
Identify this mark. How do you pass it?
Isolated danger mark — black with red horizontal band(s), TWO black spheres. She stands ON the danger, with navigable water all around — give her a respectful berth on any side. Light: white, group of two flashes (two flashes, two spheres).
Identify this mark. What does it tell you?
Safe water mark — red and white VERTICAL stripes (spherical, or pillar/spar with a single red sphere topmark). Navigable water ALL round — often a landfall or mid-channel mark. Light: white — Iso, Oc, LFl 10s or Morse "A".
Identify this mark. What does it tell you?
Special mark — yellow, with a yellow "×" topmark. Marks a feature rather than a danger: spoil grounds, exercise areas, cables, ODAS buoys. Not primarily a navigation mark — consult the chart. Light: yellow, a rhythm not used by the white lights of cardinal, isolated-danger or safe-water marks.
Identify this mark — you will not find it in the older textbooks.
Emergency wreck marking buoy — blue and yellow VERTICAL stripes, yellow upright cross topmark, alternating blue/yellow light (about 1 s each). Deployed on a NEW wreck not yet in the charts and notices; give it a wide berth on all sides until the permanent marking is established.
Region A. A pillar buoy, not a can — how do you read her?
Port-hand lateral, Region A (pillar body) — the BODY may be pillar or spar; the red colour and the red can TOPMARK carry the meaning. Leave her to PORT entering from sea.
Card backs quote the Rules — public sector information reproduced under the Open Government Licence v3.0 (source: MSN 1781 — see the Rules reference).
Independent preparatory study aligned to the MCA OOW (Yachts <3000 GT) oral examination syllabus. Not an MCA-approved course and confers no credit toward a Certificate of Competency.