Narrow Channels and Traffic Separation Schemes

Where Rules 9 and 10 sit — and what they do not give you

In short: Read Risk of Collision and Action to Avoid Collision first. Rules 9 and 10 tell you where and how to navigate in narrow channels and traffic separation schemes (TSS). They give no right of way: all the other steering and sailing rules still apply inside them.

• Both rules are in Part B Section I (COLREG Rules 4–10), so they apply in any condition of visibility.
• COLREG Rule 9 — narrow channels and fairways.
• COLREG Rule 10 — traffic separation schemes. Rule 10(a): it applies only to schemes adopted by IMO, and it does not relieve any vessel of her duties under any other rule.
• A vessel following a TSS lane has no priority over a vessel crossing the lane (MGN 364 (M+F), para 2.2). Rules 5 to 8 — look-out, safe speed, risk of collision, action to avoid — apply as everywhere else (para 2.3).
• COLREG does not define a “narrow channel”. Whether Rule 9 applies depends on the width of navigable water, the size and draught of your vessel and the traffic.
• Why TSS exist: the first scheme was set up in the Dover Strait in 1967; the 1972 COLREG was the first to recognise them; IMO has now adopted nearly 200 schemes. In the Dover Strait, collisions fell from 60 (1956–1960) to 16 twenty years later (IAIN study 1981, quoted by IMO).
• In the exam, Rule 10 is one of the COLREG rules tested most often. Expect to analyse a traffic picture and say what you would do (radar and ARPA syllabus: apply COLREG to given collision data and choose the action that avoids a close-quarters situation).

On the bridge: you are south-west bound in a lane. A power-driven ship crossing the lane is on your starboard bow, bearing steady. She is the stand-on vessel under COLREG Rule 15 — being “in the lane” changes nothing. You give way.

Rule 9 — keep to starboard, and who must not impede

In short: In a narrow channel or fairway, keep as near to the outer limit on your starboard side as is safe and practicable. Small craft, sailing vessels, fishing vessels and crossing vessels must not impede a ship that can only navigate inside the channel.

• Rule 9(a) — proceeding along the channel: keep to the starboard edge, as far as is safe and practicable. Not the centre line, and not into shallow water.
• Rule 9(b) — a vessel of less than 20 m or a sailing vessel shall not impede a vessel that can safely navigate only within the channel.
• Rule 9(c) — a vessel engaged in fishing shall not impede any other vessel navigating within the channel.
• Rule 9(d) — do not cross a channel if that impedes a vessel that can navigate only within it. That vessel may sound at least five short and rapid blasts (COLREG Rule 34(d)) if she doubts your intentions.
• Rule 9(g) — avoid anchoring in a narrow channel if the circumstances allow.
• “Not impede” is not the same as “give way”. The vessel that must not impede acts early, so that risk of collision never develops. If risk does develop, the normal rules apply in full, and the other vessel keeps her own duties (COLREG Rule 8(f)).

On the bridge: a 12 m yacht under sail tacks across a buoyed channel ahead of a deep-draught container ship. The yacht breaks Rule 9(b) if she forces the ship to alter. If she is already close and risk exists, the ship still acts under the steering rules and sounds five short blasts.

Rule 9 — overtaking and blind bends: the sound signals

In short: If you can only overtake when the vessel ahead moves over for you, ask with a whistle signal and wait for her agreement. Near a blind bend, go with particular alertness and caution and sound one prolonged blast.

• Rule 9(e)(i) — overtaking that needs action by the vessel being overtaken: signal your intention (Rule 34(c)(i)). If she agrees, she answers (Rule 34(c)(ii)) and moves to let you pass safely. If in doubt, she may sound Rule 34(d).
• Rule 9(e)(ii) — this does not relieve the overtaking vessel of her duty under COLREG Rule 13: she still keeps out of the way.
• Rule 9(f) — approaching a bend or area where other vessels may be hidden by an obstruction: particular alertness and caution, and sound Rule 34(e).
• Blast lengths (COLREG Rule 32): short blast about 1 s; prolonged blast 4–6 s.

These overtaking signals belong to narrow channels (Rule 9(e)) and are used in sight of one another. Do not use them in open water or in fog.

Rule 10 — the parts of a traffic separation scheme

In short: A TSS splits opposing traffic into one-way lanes, kept apart by a separation zone or line. Along the coast there may be an inshore traffic zone (ITZ). A precautionary area is a routeing measure but not part of the TSS.

• Traffic lane — one-way: proceed in the general direction of traffic flow for that lane (Rule 10(b)(i)).
• Separation zone or line — keeps the opposing lanes apart. Keep clear of it as far as practicable (Rule 10(b)(ii)).
• Inshore traffic zone (ITZ) — the water between the landward edge of the scheme and the coast. Vessels in an ITZ may head in any direction (MGN 364 (M+F), para 2.9).
• Terminations — the ends of the scheme, where traffic joins, leaves and converges. Navigate with particular caution there (Rule 10(f)).
• Precautionary area — not part of the TSS, so Rule 10 does not generally apply. Navigate with particular caution, and avoid it if practicable. Passing through one may still count as navigating near a TSS (MGN 364, paras 2.20–2.21).
• Areas to avoid inside a scheme (for example Varne bank in the Dover Strait) are still within the TSS, so Rule 10 applies there (MGN 364, para 2.25).
• Where to find schemes: the chart, the Admiralty List of Radio Signals and the Sailing Directions; IMO publishes the official list in Ships’ Routeing.

Rule 10 — using, joining, leaving and crossing

In short: Follow the lane in the direction of flow. Join or leave at the ends, or from the side at a small angle. Cross only if you must, on a heading at right angles to the traffic flow.

• Rule 10(b)(iii) — normally join or leave at the termination of the lane. From either side, do it at as small an angle to the general direction of traffic flow as practicable — you merge like a car on a motorway.
• Rule 10(c) — avoid crossing lanes as far as practicable. If you must cross, do it on a heading as nearly as practicable at right angles to the general direction of traffic flow.
• It says heading, not track (MGN 364 (M+F), para 2.5). With a strong tidal set you still steer 90° to the flow and accept the drift. Other ships then see your beam aspect and know at once that you are crossing, and you spend the least time in the lane.
• A crossing vessel clears the whole lane in one manoeuvre without stopping (except in an emergency). Stopping inside the lane makes you a vessel joining it, and Rule 10(b) then applies (MGN 364, para 2.6).
• Rule 10(g) — avoid anchoring in a TSS or in the areas near its terminations, as far as practicable.
• Rule 10(h) — a vessel not using a scheme keeps clear of it by as wide a margin as practicable.
• Passage planning: plot the route through the TSS, use VTS information and reports, mark the joining, leaving and alteration points, and allow for traffic density.

On the bridge: you must cross the Dover Strait lanes. Plan the crossing well away from the terminations, set a heading 90° to the lane direction, keep a proper radar and visual watch on both lanes, and remember that ships in the lane do not have priority over you — the crossing rules decide who gives way.

Rule 10 — inshore traffic zones, separation zones and who must not impede

In short: Do not use the ITZ if you can safely use the lane. Stay out of the separation zone unless crossing, joining, leaving, in an emergency or fishing. Fishing vessels, vessels under 20 m and sailing vessels must not impede lane traffic. Only two kinds of RAM vessel are exempt.

Inshore traffic zones — Rule 10(d)

• Rule 10(d)(i) — do not use an ITZ when you can safely use the appropriate lane of the adjacent scheme. But vessels of less than 20 m, sailing vessels and vessels engaged in fishing may use it.
• Rule 10(d)(ii) — any vessel may use the ITZ when en route to or from a port, offshore installation or structure, pilot station or any other place inside the ITZ, or to avoid immediate danger.
• Heavy traffic, restricted visibility or an empty-looking ITZ are not reasons to use it (MGN 364 (M+F), para 2.7).
• You may anchor in an ITZ after a propulsion or steering failure, or to shelter from heavy weather (MGN 364, para 2.8).
• Dover Strait: neither Channel VTS nor HM Coastguard can give permission to use the English ITZ against Rule 10(d). A Master who decides it is justified must report that decision to Channel VTS (MGN 364, paras 3.3–3.4).

Separation zones — Rule 10(e)

• A vessel that is not crossing, joining or leaving a lane shall not normally enter a separation zone or cross a separation line, except:
  1. in an emergency to avoid immediate danger;
  2. to engage in fishing within the separation zone.
• You may anchor in a separation zone after a propulsion or steering failure (MGN 364 (M+F), para 2.11).

Who must not impede — Rule 10(i) and 10(j)

• Rule 10(i) — a vessel engaged in fishing shall not impede any vessel following a traffic lane. Trawlers must leave enough sea room, especially when shooting or hauling long gear (MGN 364, paras 2.12–2.15).
• Rule 10(j) — a vessel of less than 20 m or a sailing vessel shall not impede the safe passage of a power-driven vessel following a lane.
• A sailing yacht motor-sailing is a power-driven vessel. The UK reads “impede” as forcing the other vessel to change course or speed (MGN 364, paras 2.16–2.17).
• As in Rule 9: act early so that risk of collision does not develop. If it does, the steering rules apply in full (COLREG Rule 8(f)).

The two exemptions — Rule 10(k) and 10(l)

• Rule 10(k) — a vessel restricted in her ability to manoeuvre while engaged in an operation for the maintenance of safety of navigation in a TSS (for example buoy work, dredging, surveying) is exempt to the extent necessary for the operation.
• Rule 10(l) — a vessel restricted in her ability to manoeuvre while laying, servicing or picking up a submarine cable in a TSS is exempt to the extent necessary for the operation.
• These exemptions came in with the 1981 amendments (in force 1 June 1983).

Exam trap: Rule 10(l) speaks only of a submarine cable. The word “pipeline” is not in Rule 10. A pipe-laying vessel in a TSS gets no Rule 10 exemption.

On the bridge — watchkeeping, reporting and the YG signal

In short: A TSS raises the look-out workload, many schemes have mandatory reporting, and every vessel is tracked. If a ship seems to break Rule 10, she can be warned with flag signal YG and reported.

Look-out and passage planning

• The OOW may be sole look-out by day only, when the Master has judged it safe. One of the factors the Master weighs is the attention necessary when navigating in or near a TSS (MGN 315 (M)).
• Passage plan: use the TSS and VTS, plot alteration points, fix the position often, and allow for traffic density.

Dover Strait reporting — CALDOVREP

• Mandatory for vessels of 300 GT and over. Vessels under 300 GT should still report if they are NUC or at anchor in the TSS or ITZ, restricted in their ability to manoeuvre, or have defective navigation equipment (MGN 364 (M+F), paras 3.7–3.9).
• South-west bound: call Dover Coastguard on VHF Ch 11, at the latest when crossing the line North Foreland light (51° 23’N, 001° 27’E) – France/Belgium border (51° 05’N, 002° 33’E).
• North-east bound: call Gris-Nez Traffic on VHF Ch 13, 2 NM before crossing the line Royal Sovereign light tower – Bassurelle light buoy – French coast (MGN 364, paras 3.10–3.11).

Vessels not complying — YG and other signals

• A vessel seen not complying with a TSS should be told by the best means available, and the VTS informed if she is within VTS coverage (MGN 364, para 2.22).
• The International Code signal YG means “You appear not to be complying with the traffic separation scheme” (MGN 364, para 2.23).
• If you receive it: check your course and position at once and act immediately to correct the situation (MGN 364, para 2.24).
• Ships are tracked by radar and AIS. A vessel found breaking COLREG is reported to her Flag State, and may be prosecuted when she arrives at a UK port (MGN 364, para 3.6).