COLREGs – The “Highway Code” at Sea

Understanding COLREGs

When you’re out on the water, especially in busy channels or during limited visibility, navigating safely becomes a matter of applying clear rules. That’s where the International Regulations for Preventing Collisions at Sea (commonly called the COLREGs) come in – effectively the maritime version of a “rules of the road” handbook. The Royal Yachting Association (RYA) reminds us that these aren’t optional guidance: they are law.

Let’s dive into what the COLREGs cover, why they matter for every vessel (big or small), and how you, whether a seasoned skipper or a new boater, can make them work in practice.

1. What exactly are the COLREGs?

  • The COLREGs consist of 38 separate rules.
  • They are divided into five main Parts (A–E):
    • A – General Rules
    • B – Steering and Sailing (especially relevant for small craft)
    • C – Lights and Shapes
    • D – Sound and Light Signals
    • E – Exemptions
  • There are also four annexes covering technical details (positions of lights/shapes, fishing vessels, sound‐signal appliances, distress signals).
  • Why it matters: The RYA emphasises this is not just good practice – “a commonly held misconception is that COLREGs are a guidance … wrong! They are the law and a proven breach may lead to prosecution, even if a collision hasn’t occurred.”

2. Key COLREGs You Should Know (especially for small boats)

For many leisure craft, the most immediately relevant chunk is Part B (Rules 4-19) – the “steering and sailing” section. According to the RYA:

  • Part B covers:
    • Keeping a proper look-out (Rule 5)
    • Making sure you’re travelling at a safe speed (Rule 6)
    • Determining whether there is a risk of collision (Rule 7)
    • Taking action to avoid a collision (Rule 8)
    • Rules for narrow channels (Rule 9)
    • Traffic Separation Schemes (Rule 10)
    • Approaching, overtaking, head-on and crossing situations (Rules 12-15)
    • The roles of give-way (Rule 18) and stand-on (Rule 17) vessels
    • Conduct in restricted visibility (Rule 19)
    • Stories like: “If a give-way vessel doesn’t take action, then the stand-on vessel must also take action.”

Bottom line: Knowing which vessel is give-way vs stand-on and acting appropriately is critical.

3. Lights, Shapes & Sound Signals

Beyond manoeuvring rules, the COLREGs set out how vessels must signal their intentions or status:

  • In Part C (Lights & Shapes) you’ll find what lights a vessel must show at night or during limited visibility—and what day-shapes should be displayed.
  • For example: Sailing vessels under 20 m are permitted to use a tri-colour navigation light, but the RYA suggests that using separate deck-level port/starboard/stern lights may help larger vessels gauge your distance more reliably.
  • Part D (Sound & Light Signals) covers what audible or visual signals must be made (or responded to) in certain conditions (e.g., restricted visibility, overtaking, or anchoring).

These rules ensure that everyone on the water can “read” what others are doing, even when visibility is poor.

4. Why It All Matters: For You and Others

Here are some concrete reasons why the COLREGs deserve your attention:

  • Legal obligation: As noted above, non-compliance can lead to prosecution – even if no collision occurs.
  • Clarity in busy or complex waters: When multiple vessels are moving, possibly under power, sail, in narrow channels or traffic separations – the rules give you a common language.
  • Safety in degraded conditions: In limited visibility or when vessels can’t clearly see each other, the rules provide when and how to act (Rule 19).
  • Avoiding blame: If a collision does occur, both vessels may be found at fault if one didn’t act when they should have.

5. Practical Tips for Skippers & Crew

Here are some actionable considerations to make the COLREGs work for you:

  • Always maintain a proper look-out: Visual, auditory, radar (if fitted) – don’t rely solely on one method.
  • Assess safe speed: What’s safe in daylight might not be in fog, or close to traffic separation schemes.
  • Be proactive: Don’t wait! If you anticipate a crossing/overtaking situation, start action early.
  • Know your vessel type and lights/shapes requirements: Even smaller craft have obligations.
  • If you’re the stand-on vessel: Stay alert. If the give-way vessel fails to act, you must avoid collision too.
  • Stay updated and trained: The RYA’s powerboat and skipper theory training cover the COLREGs.

6. The Take Away

For anyone operating on the water, from dinghies to large yachts, the COLREGs are essential. They are not optional guidelines; they form a legal framework designed to keep everyone safe. If you treat them as your maritime “highway code”, you’ll be far more likely to arrive at your destination safely and responsibly.

Buy your copy of the International Regulations for Preventing Collisions at Sea here.