Question 1

You are approaching a channel junction. You see a buoy: GREEN body with a single RED horizontal band; conical shape; green light showing Fl(2+1)G. What does this mean and which channel is preferred?

Accepted Answer

PREFERRED CHANNEL MARK — PREFERRED CHANNEL TO STARBOARD. In IALA A, a modified lateral mark with: GREEN body + RED horizontal band = the preferred channel is to STARBOARD (the primary/main channel lies to starboard). The light Fl(2+1) in the colour of the main body colour (green) confirms this — group of 2 flashes + 1 flash in green. The secondary (minor) channel lies to PORT of this mark. At a channel junction, this mark tells you: if you take the STARBOARD side of this mark, you are in the PRIMARY channel; if you take the PORT side, you are in the secondary channel. Action: in the PRIMARY channel, leave this mark to PORT (as you would any green starboard-hand mark in IALA A). If using the SECONDARY channel, leave it to STARBOARD. Equivalent RED with GREEN band: preferred channel to PORT. Preferred channel (modified lateral) marks are examined because they require the OOW to understand both the channel hierarchy AND the passing convention. The IALA system defines two variants: (1) PREFERRED CHANNEL TO STARBOARD: RED body with GREEN horizontal band, or equivalent — the mark has a red body (port mark character) but with a green band. Light Fl(2+1)R. In IALA A: leave to PORT on the preferred channel; (2) PREFERRED CHANNEL TO PORT: GREEN body with RED horizontal band. Light Fl(2+1)G. Leave to STARBOARD on the preferred channel. The Fl(2+1) light characteristic — group of 2 then 1 — is unique to preferred channel marks and immediately distinguishes them from plain lateral marks. The "preferred channel" is typically the deeper, main navigable channel — vessels should use it unless they specifically need the secondary channel for their destination. The OOW must understand that at a channel junction, the choice of which side of the mark to pass affects which channel is entered.

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).