Part B · Section II

COLREGs Rule 18: Responsibilities between vessels

Rule 18 sets the pecking order: a power-driven vessel keeps out of the way of sailing, fishing, restricted (RAM) and not-under-command (NUC) vessels; a sailing vessel keeps clear of fishing, RAM and NUC vessels; and everyone avoids impeding a vessel constrained by its draught.

What Rule 18 says

  1. Except where Rules 9, 10 and 13 require otherwise:
  2. A power-driven vessel underway keeps out of the way of a vessel not under command, a vessel restricted in her ability to manoeuvre, a vessel engaged in fishing and a sailing vessel.
  3. A sailing vessel underway keeps out of the way of a vessel not under command, a vessel restricted in her ability to manoeuvre and a vessel engaged in fishing.
  4. A vessel engaged in fishing keeps out of the way of a vessel not under command and a vessel restricted in her ability to manoeuvre.
  5. Any vessel other than NUC or RAM shall, if circumstances admit, avoid impeding a vessel constrained by her draught showing its signals. The CBD vessel must navigate with particular caution.
  6. A seaplane on the water generally keeps well clear of all vessels. A WIG craft taking off, landing or flying near the surface keeps well clear of all vessels.

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

Remember the order with 'NUC, RAM, CBD, Fishing, Sailing, Power'. A yacht must give way to a fishing boat that is actually fishing, but not to one motoring home with its gear stowed.

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 power always give way to sail?

No. Rule 18 makes power keep clear of sail, but only 'except where Rules 9, 10 and 13 otherwise require'. A sailing yacht overtaking, or impeding a ship in a narrow channel or a TSS lane, must keep clear.

What is the order of right of way at sea?

From most to least privileged: not under command, restricted in ability to manoeuvre, constrained by draught (others avoid impeding), fishing, sailing, power-driven. Seaplanes and WIG craft keep clear of everyone.