Part B · Section I

COLREGs Rule 9: Narrow channels

Rule 9 says in a narrow channel or fairway you keep as near to its starboard side as is safe, and small or sailing vessels must not impede a vessel that can only navigate safely within the channel.

What Rule 9 says

  1. Keep as near to the outer limit of the channel on your starboard side as is safe and practicable.
  2. A vessel under 20 metres or a sailing vessel shall not impede a vessel that can safely navigate only within the channel.
  3. A vessel engaged in fishing shall not impede any other vessel navigating within the channel.
  4. Do not cross a channel if that impedes a vessel that can only navigate within it. That vessel may sound five short blasts if in doubt of your intentions.
  5. Overtaking in a channel, when the overtaken vessel has to act to allow it, is agreed by sound signals: two prolonged and one short (starboard side) or two prolonged and two short (port side); agreement is prolonged, short, prolonged, short.
  6. Approaching a bend or area where other vessels may be hidden, sound one prolonged blast.
  7. Avoid anchoring in a narrow channel if circumstances admit.

This is a plain-English summary, not the official wording. For the exact text, see the IMO convention. In UK waters the rules are given legal force by the Merchant Shipping (Distress Signals and Prevention of Collisions) Regulations.

What it means on a yacht

In the Solent's Thorn Channel or any buoyed harbour approach, a yacht should stay outside the deep-water channel where possible and never tack across a ship's bows. 'Not impede' means acting early, before a risk of collision even develops.

Practise it

Test yourself on who gives way in the free COLREGs trainer, or print the rules of the road cheat sheets for the chart table.

Other rules in Part B

Frequently asked questions

Does a sailing boat have right of way over a ship in a narrow channel?

No. Under Rule 9(b) a sailing vessel or any vessel under 20 m must not impede a vessel that can only navigate safely within the channel. Rule 18 'power gives way to sail' does not override this.