Question 1

You observe a yellow X-shaped (cross) topmark on a yellow buoy with a yellow light showing Fl.Y (yellow flashing). The chart shows this area marked with a yellow symbol. What is this mark and what might it indicate?

Accepted Answer

SPECIAL MARK. Colour: entirely YELLOW. Topmark: yellow X-shape (St Andrew's cross / saltire). Light: Fl.Y (yellow light, any rhythm — the yellow colour of the light is what distinguishes it from all other IALA lights which are white, red, or green). Meaning: a special mark does NOT indicate a navigational hazard — it marks a special area or feature defined on the chart. Common uses include: traffic separation scheme boundaries; MSI broadcasting areas; cable or pipeline marks; military exercise areas; ocean data acquisition systems (ODAS buoys); speed limit zones; fish farm boundaries; bathing area limits; outfall pipes; spoil grounds. Action: consult the chart to determine the specific purpose of the mark in this area. Do NOT treat it as a navigational danger mark unless the chart identifies a specific hazard associated with it. Special marks are the "catch-all" category of the IALA system. The yellow colour (body AND light) uniquely identifies them — no confusion with the standard white, red, or green lights of other IALA marks. The X topmark is the only X-shaped topmark in the system. At OOW level, the critical knowledge is: (a) identification (yellow everything + X topmark); (b) that a special mark does NOT indicate a navigational danger unless the chart specifically associates one with it; (c) that the chart must be consulted to understand the specific purpose of any special mark encountered. ODAS (Ocean Data Acquisition System) buoys: large yellow data-collecting buoys in the open ocean that transmit weather/oceanographic data — important not to approach or foul. Spoil ground markers: dredge spoil dumping areas marked by yellow special marks. Fish farm marks: increasingly important in coastal waters — yellow special marks may encircle an aquaculture installation. The OOW should always cross-reference the chart when encountering a special mark — its significance depends entirely on the chart annotation.

Question 2

Your examiner asks: in IALA System A (used in the UK and Europe), a red can buoy is seen to port on the starboard side of a channel. Are you entering or leaving harbour, and on which side do you pass it?

Accepted Answer

IALA System A — Red to PORT when entering harbour (proceeding from seaward). Red can buoy on your port side means you are on the starboard side of the channel, heading seaward (leaving harbour). To re-enter, you would keep the red buoy to PORT. Rule: In IALA A: RED = PORT = entering harbour (coming from sea). Green = Starboard = entering harbour. Memory aid for IALA A: "Red to Port Returning." The question states the red buoy is to port — therefore you are ENTERING HARBOUR correctly, keeping the channel to starboard. Pass the red buoy keeping it to PORT (leave it on your port side). In IALA B (Americas, Japan, Philippines, Korea): colours are reversed — red to starboard entering. IALA System A covers Europe, Africa, India, Australia, and most of Asia. IALA System B covers the Americas, Japan, the Philippines, and South Korea. The fundamental difference is the colour assignment for lateral marks. IALA A: PORT side mark = RED (can or spar shape, red light any rhythm); STARBOARD side mark = GREEN (conical shape, green light any rhythm). IALA B: PORT side mark = GREEN; STARBOARD side mark = RED. The "conventional direction of buoyage" defines port and starboard: in harbour approaches and rivers, it is the direction proceeding from seaward into the harbour/upstream. On coasts, the conventional direction runs clockwise around continents (in the northern hemisphere: north along the east coast, east along the south coast, south along the west coast). A candidate serving on UK vessels must know IALA A thoroughly and understand IALA B for voyages to the Americas. The examiner will use a colour card or verbal description and expect immediate identification of the mark type, meaning, and passing action.

Question 3

On radar you detect a buoy at 358° 0.8nm. As you approach visually you see: two black cones both pointing UP as topmarks; black upper body, yellow lower body; the light characteristic is VQ (very quick flashing — approximately 120 flashes per minute). What is this mark, what does it indicate, and how do you pass it?

Accepted Answer

NORTH CARDINAL MARK. Topmark: two cones BOTH pointing UP (like an arrow pointing north). Colour: black over yellow (black upper, yellow lower). Light: white VQ (very quick) or Q (quick) — uninterrupted. Meaning: safe water lies to the NORTH of this mark. The mark indicates a hazard to its south — the safe side to pass is to the NORTH. Action: pass the mark to the NORTH — i.e., keep the mark to the SOUTH of you as you pass. In this scenario the buoy is bearing 358° (nearly north), so you are approaching from the south — the mark is warning you of danger to your south; you are already in the safe water north of the mark. Monitor: do not pass to the south of this buoy. Cardinal marks are the most systematically tested buoyage topic at OOW level because the examiner can test all four quadrants with slight variations. The cardinal system is based on the compass: the mark indicates the safe water lies in the direction of the compass point named. NORTH cardinal: safe water to the NORTH. SOUTH cardinal: safe to the SOUTH. EAST cardinal: safe to the EAST. WEST cardinal: safe to the WEST. Topmark memory aid: think of the clock face — N = both points UP (12 o'clock, both up); S = both points DOWN (6 o'clock, both down); E = both points OUT (3 o'clock, open to east); W = both points IN (9 o'clock, hourglass shape, like a W). Colour: N = black over yellow (black on top); S = yellow over black (yellow on top); E = black-yellow-black banding; W = yellow-black-yellow banding. Light characteristics (all white): N = VQ or Q (continuous); S = VQ(6)+LFl or Q(6)+LFl (6 quick + long flash — the 6 at the bottom = 6 o'clock = south); E = VQ(3) or Q(3) (3 groups = 3 o'clock = east); W = VQ(9) or Q(9) (9 groups = 9 o'clock = west).