Narrow Channels.
(a) A vessel proceeding along the course of a narrow channel or fairway shall keep as near to the outer limit of the channel or fairway which lies on her starboard side as is safe and practicable.
(b) A vessel of less than 20m 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 or 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) (i.e. at least 5 short and rapid blasts) if in doubt as to the intention of the crossing vessel.
(e) (i) In a narrow channel or fairway, when overtaking can take place only 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 a 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.
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 should take their responsibilities very seriously in these areas, not only for safety’s sake but because such places are closely monitored and penalties are very high.
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. Though a narrow channel is small for you, it may be very big for small vessels.
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 publications.
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.
Looking at Rule 9(b), what constitutes ‘impeding’? If a small vessel gets close under the bows of a large vessel, it is likely to run it down and not even notice. Many harbour authorities 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. Professional seamen are often given anxious moments by smaller craft. 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.