Rule 9: Narrow Channels

Here’s Rule 9:

(a) A vessel proceeding along the course of a narrow channel or fairway shall keep as near to the outer limit or the channel or fairway which lies on her starboard side as is safe and practicable.

(b) A vessel of less than 20 m in length or a sailing vessel shall not impede the passage of a vessel which can safely navigate only within a narrow channel or fairway.

(c) A vessel engaged in fishing shall not impede the passage of any other vessel navigating within a narrow channel or fairway.

(d) A vessel shall not cross a narrow channel of fairway if such crossing impedes the passage of a vessel which can safely navigate only within such channel or fairway. The latter vessel may use the sound signal prescribed in Rule 34 (d) if in doubt as to the intention of the crossing vessel.


(i) In a narrow channel or fairway when overtaking can only take place if the vessel to be overtaken has to take action to permit safe passing, the vessel intending to overtake shall indicate her intention by sounding the appropriate signal prescribed in Rule 34 (c)(i). The vessel to be overtaken shall, if in agreement, sound the appropriate signal prescribed in Rule 34 (c)(ii) and take steps to permit safe passing. If in doubt she may sound the signals prescribed in Rule 34 (d).

(ii) This rule does not relieve the overtaking vessel of her obligation under Rule 13.

(f) A vessel nearing a bend or an area of narrow channel or fairway where other vessels may be obscured by an intervening obstruction shall navigate with particular alertness and caution and shall sound the appropriate signal prescribed in Rule 34 (e).

(g) Any vessel shall, if the circumstances of the case admit, avoid anchoring in a narrow channel.

Rule 9: Narrow Channels Explained

Rules 9 and 10 deal with the busiest waters you will find: narrow channels and the special Traffic Separation Schemes laid down, to bring order to congested and often constrained shipping lanes, their junctions and port approaches.

OOW’s would do well to take heed of their responsibilities in these areas, not only for safety’s sake but because such places are closely monitored and penalties are sometimes, quite rightly, levied on those who break the rules.

To put it simply, stay as far as possible to the starboard side of the channel.  Small craft may and frequently do, obstruct the passage of larger vessels.  You must remember that a very narrow channel for you may seem like a broad unobstructed expanse of water, for a small vessel or yacht.

When deciding where to cross a narrow channel, or even when entering it, remember that you not only have Rule 9(d) to consider, but also any local recommendations or bylaws which may be in place, governing where and when such manoeuvres should occur.  This will normally be indicated in your nautical almanac, on a large-scale chart and, most usefully, on the harbour guides produced by port authorities.

One example in Britain is the ‘recommended yacht track’ laid down for the approaches to Ramsgate, which shows a crossing point for small craft and a safe route which keeps them close to, but out of, the narrow and busy deepwater shipping channel.  Another, worthy of note, is the small craft channel on the western side of PortsmouthHarbour entrance.

Looking at Rule 9(b), what constitutes ‘impeding’?   Let’s take a pragmatic view.  If a small vessel gets close under the bows of a vessel of 150m (490ft) or more, it is likely to run it down and not even notice.  Many harbourmasters with a mixed jurisdiction of commercial and leisure users, are worried that a pilot or master will, sooner or later, try to take drastic action to avoid hitting careless small boats, which will cause a major shipping catastrophe.  Given the limited manoeuvrability of large vessels, their equally limited view from the bridge and the time it takes for them to stop, this is open to debate.  Certainly, professional seamen are often given anxious moments by smaller craft and that anxiety ultimately brings pressure to bear on the freedom of the water for us all.  So, again, small craft should stay well clear, which is what this rule is emphasising.

As if to qualify how close you need to get before a vessel is impeded, Associated British Ports introduced their new ‘Area of Concern’ for Southampton Water and its approaches during 1993.  Any vessel of 150m (490ft) or more entering the notified area immediately has what is known as a ‘Moving Prohibited Zone’ (MPZ) stretching 1000m (0.6nm) ahead of it and 100m (330ft) on each side.  All small craft are banned from this zone.  When you think about it, 0.6nm is not very far from the bows of a ship moving at 10 knots, which will take only 3 min to cover this distance through the water.

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Rule 9 Narrow Channels
Rule 9 Narrow Channels
Colregs rule 9 narrow channels
Colregs rule 9 narrow channels
narrow channels explained
narrow channels explained


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