ColRegs: A Simple Guide to International Collision Regulations

The International Regulations for Preventing Collisions at Sea, commonly known as ColRegs, are quite simply the ‘rules of the road’ for ships and other vessels at sea. Just as we have highway codes for driving cars, ColRegs provide the essential framework for safe navigation on the water.

Key facts about ColRegs:

• They are the law, not just guidance
• They apply to all vessels upon the high seas and in all waters connected therewith navigable by seagoing vessels
• A proven breach may lead to prosecution, even if a collision hasn’t occurred
• They were adopted as a convention of the International Maritime Organisation in 1972

ColRegs exist to prevent collisions and save lives. They make it clear when you are the ‘stand on’ vessel, when you are the ‘give way’ vessel, and what correct action to take when in close quarters with other vessels to avoid a collision.

The bottom line: Anyone using any sort of watercraft as a means of transport – whether motor or sail – should familiarise themselves with ColRegs.

There are 38 separate rules within ColRegs, divided into five main parts:

Part A: General (Rules 1-3)

• Application and responsibility
• Definitions

Part B: Steering and Sailing Rules (Rules 4-19)

Most important for small boats – these rules cover:

• Conduct of vessels in any condition of visibility
• Conduct when vessels are in sight of each other
• Conduct in restricted visibility

Part C: Lights and Shapes (Rules 20-31)

• Requirements for navigation lights and day shapes
• What lights and shapes different types of vessels must display

Part D: Sound and Light Signals (Rules 32-37)

• Sound signals in various conditions
• Distress signals

Part E: Exemptions (Rule 38)

• Special circumstances for certain vessels

Plus Four Annexes covering:

• Technical details of lights and shapes
• Additional signals for fishing vessels
• Sound signal appliances
• Distress signals

Give Way Vessel

• The vessel that must take action to avoid collision
• Must take early and substantial action to keep well clear
• Action must be clearly apparent to the other vessel

Stand On Vessel

• The vessel that should maintain course and speed
• Must NOT impede the give way vessel’s actions
• MUST take action if the give way vessel fails to act or if collision becomes unavoidable

Important: No vessel has absolute ‘right of way’ under ColRegs. Both vessels have responsibilities to prevent collision.

Rule 5: Look-out

Every vessel shall at all times maintain a proper look-out by sight, hearing and all available means to make a full appraisal of the situation and risk of collision.

Rule 6: Safe Speed

‘Safe speed’ is one of the fundamental rules. This doesn’t always mean slow, but driving to the conditions. You must be able to stop within the distance of clear water ahead.

Rule 8: Action to Avoid Collision

• Any action to avoid collision should be positive, made in ample time and with due regard to good seamanship
• If sufficient sea room is available, alteration of course alone may be the most effective action
• Action should result in passing at a safe distance

Rule 9: Narrow Channels

• Keep to the starboard (right) side of channels
• Small vessels must not impede vessels that can only navigate safely within the channel
• Don’t cross a channel if it impedes larger vessels

Rule 13: Overtaking

• Overtaking vessel is always give way
• Must keep clear until finally past and clear
• Applies regardless of whether you’re power or sail

Rule 15: Crossing Situations

When two power vessels are crossing:

• Vessel with the other on her starboard (right) side gives way
• Give way vessel should avoid crossing ahead of the stand on vessel

Rule 18: Responsibilities Between Vessels

Hierarchy of responsibility (most manoeuvrable gives way to least):

1. Power vessels give way to sailing vessels
2. Sailing vessels give way to fishing vessels
3. Fishing vessels give way to vessels not under command
4. All vessels give way to vessels restricted in ability to manoeuvre

Exception: Sailing vessels must not impede large vessels in narrow channels

Critical timing consideration: Two boats travelling at 10 knots close at one mile every three minutes. The distance to the horizon for most small powerboats is about two miles – that’s only six minutes from seeing to potential collision!

This makes early recognition and prompt action essential.

Understanding what other vessels are doing is crucial for applying ColRegs correctly.

Basic Power Vessel Lights

• Red port (left) light – visible from dead ahead to 112.5° port
• Green starboard (right) light – visible from dead ahead to 112.5° starboard
• White stern light – visible 135° from dead astern
• White masthead light – visible 225° ahead

What You Can Determine

From lights you can identify:

• Power driven vessels
• Sailing vessels
• Vessels at anchor
• Tug and tow combinations
• Fishing vessels
• Dredgers
• Vessels restricted in their ability to manoeuvre

Day Shapes

During daylight, vessels display black shapes to indicate their status:

• Cone apex down – vessel motoring (including motor-sailing yachts)
• Ball – vessel at anchor
• Diamond – vessel restricted in ability to manoeuvre

Manoeuvring Signals (In sight of each other)

• 1 short blast – “I am altering course to starboard”
• 2 short blasts – “I am altering course to port”
• 3 short blasts – “I am operating astern propulsion”
• 5 short blasts – “I do not understand your intentions” or doubt you’re taking sufficient action

Restricted Visibility

• 1 long blast every 2 minutes – power vessel making way
• 2 long blasts every 2 minutes – power vessel stopped
• 1 long + 2 short every 2 minutes – sailing vessel

Before You Go

• Know the rules – ignorance is no defence in law
• Practice recognition of lights and shapes
• Understand your vessel’s manoeuvrability limitations

While Underway

• Maintain proper lookout at all times
• Assess situations early – don’t wait until close quarters
• Take positive action when required – make it obvious to other vessels
• Communicate your intentions with sound signals when appropriate

In Doubt

• Act defensively – especially around large commercial vessels
• Give wide berth – it costs nothing but provides safety margin
• Remember: A large ship may not be able to see you, even if you can see it

When operating in Traffic Separation Schemes:

• Use appropriate traffic lane for your direction
• Cross lanes at right angles to traffic flow
• Don’t impede vessels following traffic lanes
• Keep clear of separation zones unless crossing

Remember: Failure to comply with ColRegs is a criminal offence that can carry a maximum penalty of two years in prison and/or unlimited fine.

Common prosecutable offences include:

• Motoring the wrong way in separation lanes
• Failure to give way when required
• Not maintaining proper lookout
• Operating at unsafe speed

RYA Courses covering ColRegs:

• Day Skipper Theory – first comprehensive introduction
• Coastal Skipper Theory – more advanced applications
• Essential Navigation and Seamanship – great refresher course
• Practical powerboat courses – real-world application

Key Training Elements:

• Understand when you’re give way or stand on vessel
• Recognize responsibilities in narrow channels
• Identify vessels from their lights and shapes
• Know manoeuvring signals
• Practice collision avoidance scenarios

1. ColRegs are law – you must comply, not just understand
2. Proper lookout is mandatory at all times
3. Early action is more effective than last-minute manoeuvres
4. No absolute right of way – both vessels have collision avoidance duties
5. When in doubt, act defensively – especially around larger vessels
6. Small vessels must not impede larger vessels in channels
7. Practice recognition of lights, shapes, and signals
8. Get proper training – theoretical knowledge needs practical application