Question 1

On approach to a harbour you see a fixed light on the shore. The light shows WHITE when bearing 045°–095° from the sea; RED when bearing 095°–115°; GREEN when bearing 010°–045°. You are approaching bearing 098° to the light. What does the light tell you and what action do you take?

Accepted Answer

SECTOR LIGHT — a fixed light on a structure (lighthouse, harbour entrance pier, breakwater head) that shows different colours through different arcs of the horizon. Reading your situation: your approach bearing TO the light is 098° — so you are observing the light from the 098° direction from seaward. At 098°, the light shows RED — you are in the RED sector. In a typical sector light arrangement: WHITE sector = safe approach (centre of navigable channel); RED sector = danger on the right (starboard) side — vessel is too far to the right of the channel; GREEN sector = danger on the left (port) side. Action: you are in the red sector = TOO FAR TO STARBOARD. Alter course to PORT (towards the white sector — bearing 045°–095° from you). When the light changes to white, you are in the safe channel. Monitor continuously — track INTO the white sector and maintain it. Sector lights are one of the most practical and powerful navigation aids in coastal and harbour approach navigation. The colour sectors are designed so that the WHITE sector covers the safe approach track. RED and GREEN sectors warn of danger: convention (which may vary — ALWAYS check the chart and pilot book) is typically: GREEN sector = too far to port (port side danger); RED sector = too far to starboard (starboard side danger). Memory aid: "Green means go to the right to get back to white; Red means go to the left." Or: think of traffic lights — if you're in the red, stop and correct. In this question: bearing 098° puts the vessel just 3° into the red sector (at 095°-115°) — the correction needed is small (3-4° to port to reach the white sector edge at 095°). Sector light use in practice: once identified on the chart (symbol shows the sectors by colour), the pilot or passage plan should specify: "approach on white sector of [light name], bear 060°-090°." The OOW monitors the colour continuously — any change from white to coloured indicates drift from the safe track.

Question 2

You are OOW on a 180 GT coastal supply vessel. At night you observe a small sailing vessel showing only a combined red and green lantern at the bow — no white lights visible anywhere. What is this vessel legally showing and are you required to give way?

Accepted Answer

Combined bow lantern (bicolour lantern) — red (port) and green (starboard) sectors combined in one fitting at the bow — is permitted for sailing vessels under 20m in length under Rule 25(b) and (c): Rule 25(b) permits a combined lantern (red/green/white all in one unit at the masthead); Rule 25(c) permits an all-round white light plus the sidelights. For very small vessels under 7m: Rule 25(d) — if not reasonably practicable to show the prescribed lights, show an electric torch or lighted lantern showing a white light in sufficient time to prevent collision. The vessel showing only the bicolour bow lantern without any white sternlight is technically non-compliant unless it is under 7m using the Rule 25(d) exemption. However: it IS a sailing vessel regardless — you must give way under Rule 18(a)(v). Monitor carefully — the lack of sternlight makes aspect determination difficult. Use radar to determine course and speed. Small sailing vessel lighting arrangements are tested at near-coastal level because coastal waters in the UK contain large numbers of recreational sailing vessels, yachts, and small craft. Rule 25 permits multiple lighting options for sailing vessels, and the variety means the OOW must be able to identify sailing vessel status from whatever lights are shown. Key Rule 25 variants: (a) standard (any size): separate sidelights + sternlight; (b) under 20m: optional combined tricolour at masthead instead; (c) additional option: all-round red over green lights at the top of the mast to be more visible; (d) under 7m or rowing boats: white torch/lantern when in danger of collision. The COLREGs obligation to give way to sailing vessels (Rule 18(a)(v)) applies regardless of whether the sailing vessel is showing its lights perfectly. Non-compliance with light rules by the sailing vessel does not remove the power vessel's give-way obligation — Rule 2(a) requires taking all precautions required by ordinary seamanship.

Question 3

Approaching a harbour entrance, you see (from seaward): a red can buoy to the north of the channel, a green conical buoy to the south of the channel, then a port-hand mark showing Fl.R every 4 seconds. You are heading west (270°) into the harbour. Describe how you navigate through these marks.

Accepted Answer

IALA System A — entering harbour heading west: "Red to Port Returning." (1) Red can buoy to the NORTH of the channel: it is on the port side of the channel (keep it to port) — it marks the northern edge of safe water; your channel track runs to the south of it; (2) Green conical buoy to the SOUTH: it is on the starboard side — keep it to starboard; your channel track runs to the north of it; (3) Fl.R every 4 seconds port lateral mark ahead: red light, any rhythm = port hand mark — keep this to PORT as you pass through the entrance. Navigation: steer a course keeping the red buoy to your port (north of track), green buoy to your starboard (south of track), and the Fl.R to your port as you enter. The area of safe navigation is between the red (port) and green (starboard) lateral marks. Lateral mark navigation is the most practical buoyage skill for coastal and near-coastal OOWs. The key principle: "conventional direction of buoyage" defines port and starboard — in harbour approaches it is from seaward into the harbour. The OOW heading west into a harbour is heading IN the conventional direction (from sea to harbour) — so IALA A port/starboard conventions apply directly: RED = PORT side of safe water (keep to port), GREEN = STARBOARD side (keep to starboard). The phrase "Red to Port Returning" summarises this for IALA A. The Fl.R light characteristic: in IALA A, port lateral marks use RED lights; starboard lateral marks use GREEN lights. Any rhythm of red flashing = port hand mark; any rhythm of green flashing = starboard hand mark. The light rhythm (4 second period in this case) does not change the colour convention — only cardinal marks have specific group-count requirements. At near-coastal OOW level, the examiner expects instant confident application of IALA A conventions in realistic harbour approach scenarios.