COLREGS, Lights & Sailing at Night

Despite learning all my lights and being a nerd with the Coastguard Boating Education flash cards, when you are at sea at night it is really hard to decipher navigation lights on other boats.

I think the main difficulty I have is knowing how close you are to the other boat. We don’t have radar on board, so only have our eyes to judge. Is it a huge ship far away or is it a small ship really close? Who knows! Either way, I have no idea how close we got to the fishing boat we passed on the way back from the Sounds in January.

Here is everything I need to refresh for the Ocean Yachtmaster course I am currently doing:

I can highly recommend this online course if you are wanting to brush up on your knowledge:

COLREGS – are the international collision regulations at sea and they are designed to ensure that boats know who gives way to who.

These rules apply to everyone on the water – boats and even sea planes!

One of the most important rules in the COLREGs is that all vessels shall maintain a proper lookout at all times. This means that you need to use not just your eyes but your ears as well – and if you have other means such as AIS and Radar – then great use those as well. If boats don’t obey this rule then all the other rules are pretty much useless. You wouldn’t drive your car along the street without looking right?!

Another important rule is that boats need to operate at a safe speed so that you can take proper action to avoid a collision – this means you have to take in to account the visibility, traffic density, your vessels manoeuvrability and distance required to stop, the state of the weather and sea conditions, and the depth of the water.

So if you are keeping a good lookout and notice another boat heading in your direction, you need to next determine if a risk of collision exists. A good way of doing this is lining up the other boat with a fixture on your own vessel – like a stanchion for example. If the boat stays in line with that (the bearing remains the same) then there is a risk of a collision.

So the next step is to figure out what the other vessel is up to and then make a decision on who is going to give way to whom.

There are a few different ways of doing this – some will be obvious, and others require a bit more consideration. But you will need to take some action and it should be made in ample time and with consideration of good seamanship.

The give way boat can take action by slowing down, stopping or changing course and doing so in a manner that the other boat can see that you have done this and they can stand on.

So how do you identify what the other boat is up to and decide if you are going to give way or not? Lets start with some easy ones:

In Narrow Channels

Boats should keep to the right hand side of the channel – and pass port side to port side.

If you are a small vessel – yacht or powerboat, you should give away to all vessels who can only navigate in this channel.

So here in Lyttelton for example – we can sail all over the place, but the ships can only navigate down one strip of the harbour which is dredged. We must give way to them because they are “constrained by their draft”.

If you get in their way – they will give you five short blasts on their horn which basically means “Get out of my way!!!!”. (Trust me this is not fun…)

At Anchor

People who are under way tend to give way to boats which are anchored. (see this is all common sense people!!)

If you are at anchor – you must show an all round white light. Or during the day – a black ball suspended at the bow. If the vessel is over 50m, then they show two all round white lights – one at the front and one at the stern. If the vessel is over 100m in length then they must also show other lights to illuminate the decks.

Boats less than 7m and not going faster than 7 kts

If you are a fast manoeuvrable boat, and not restricted in the way  – then you should give way to smaller boats

At night they also only need to show an all round white light, or if you are in a dinghy you can use a torch. Basically just try not to run these slow little guys over, and likewise, if you are small and slow you might not want to be navigating through busy shipping lanes at night if people are unlikely to be able to see you. (just sayin’!!)

Boats Navigating at Night – Port, Starboard & Stern Lights

These are shown when a vessel is under way (i.e. not at anchor) and help you to identify which direction a vessel is travelling. If you can see both the red and green at the same time, then it means they are heading straight for you!

If you can only see a white light then it could either be a vessel at anchor, a slow vessel travelling at less than 7kts or a vessel travelling away from you – its stern light.


Yachts or if you are from America – Sailing Boats

Yachts under 20m, when sailing must show a port, starboard and stern light and they can be combined in a tri-coloured mast head light.

If the yacht is motoring then it also needs to show a seperate stern light and a masthead white light.

If the motor is on – then you are considered to be a power driven vessel and those rules apply – see below.

Yachts  – when they are sailing, have right of way over power boats – including ships when you are out at sea. When yachts are on starboard tack, they have right of way over yachts on port tack. And leeward boats have right of way over the windward boat when they are both on the same tack. (I won’t go in to heaps of detail on this but its worth doing some more research on this if you are planning on sailing in the vicinity of any other yachts)

Power Boats

Powerboats over 12 metres in length must show the port and starboard lights, a stern light and a mast head light – which should be 1 metre higher than the sidelights.

If the powerboat is less than 12 metres then it can combine its stern and masthead light in to one all round white light.

Power boats give way to other boats approaching on their right hand side.


Note that in the picture above, say the white boat doesn’t look like it is going to give way and the stand on vessel decides to take action themselves – they should turn to starboard – if they went to port and the other guy decided to finally show that he was giving way then you could cause another crash.

Towing Light

If you are towing another vessel, you display a yellow light instead of a stern light. This means that you have right of way over most boats. When you are towing you a restricted in your ability to manoeuvre, but you still give way to anyone who is anchored, aground, and constrained by their draft.

Under Way & Making Way

Under way, means that a vessel is not anchored, docked or secured. Making way means that it is actually moving through the water/over the ground.

Vessels Not Under Command

These are vessels which are unable to manoeuvre and keep out of the way of anyone else. Perhaps they have lost all power to their engines or broken their rudder or something like that.

They show two in line all round red lights or two red balls during the day. If they are actually making way through the water then they must show port, starboard and stern lights too.

I remember this by thinking of two red stop lights – i.e “Stop stop these guys are not under command”

Now this is where it gets a bit more complicated…!


Vessels Over 50m in length

Must show two white mast head lights (facing forward) and one white stern light. The front light should be lower than the main masthead light. They also show port & starboard lights.

Vessels Aground

Obviously if a vessel is aground then it isn’t going to be able to give way to anyone else! These guys show two all round red lights over one white.

Vessels Restricted in their Ability to Manoeuvre

These vessels are restricted in their ability to move because of the nature of the work they are undertaking – so they might be dredging, towing, launching aircraft or something like that.

They show three lights all in line red, white red or a ball, diamond, ball during the day.

If they are fishing or dredging, and this might be a hazard to other ships, then they will display two green lights or two diamonds on the safe side, and two red lights or two red balls on the side with the obstruction.

Basically everyone except vessels not under command or aground, must give way.

Not sure how I remember this one but I seem to be able to!

Vessels Constrained by their Draught

These are big ships who are restricted to the channel, and can not deviate or they will run aground. They give way to vessels not under command and vessels restricted in their ability to maneuver, but everyone else gives way to them.

They show three all round red lights in a line or a cylinder during the day.

Pilot Vessel

Shows a white over red light.

I remember this one with the rhyme “White over red, the pilot is out of bed”

Vessel Fishing

A vessel fishing usually shows a red over white light or two triangles facing point to point (wine glass shape)

I remember this one with the rhyme “Red over white, fishing at night”

However they can also show a green over white light if they are trawling. If they have a single triangle out to one side, or a single all round white light, then this indicates that there is fishing gear extending out that side for 150m.

Vessels Towing

If the length of tow is less than 200m the towing vessel shows two all round white lights or a diamond shape and a yellow stern light. The vessel being towed shows their normal lights.

If the length of tow exceeds 200m, then they display three all round white lights.

Other Rules of the Road

In Harbours

Smaller boats should give way to any ships over 50m in length.

In Narrow Channels or meeting head on.

Vessels should stick to the starboard side of the channel, alter course to starboard and pass port to port.

When Overtaking

The overtaking vessel gives way to the stand on vessel being overtaken. The stand on vessel can pass either side, but should make their intentions clear. The stand on vessel should maintain their course, and avoid speeding up to race the passing vessel or swerving over in front of them to stop them from being able to overtake… 😉

You know you are the overtaking vessel if you can see the other vessel’s stern light. If you can’t see that then you are a crossing vessel and the ‘give way to your right’ rule applies.

If you are overtaking and want to let the other vessel know what you are doing – you sound two long blasts followed by two short blasts. This means I am going to overtake you on your port side.

The stand-on boat being overtaken and sound a reply with one long one short one long and one short and moves over to the right.

Sailing Vessels

Power boats should give way to yachts.

We have got heaps of crazy yacht rules, but basically those on port tack, give way to those on starboard, and windward boat gives way to the leward boat. Alternatively in a race whoever yells the loudest and has the biggest balls usually gets their own way.

Power Vessels Crossing

You must give way to a vessel on your starboard/right hand side. If the vessel to your left does not appear to be giving way to you, then you should turn to starboard, because if you turn to port (or towards them) and they finally figure out what they are doing and try to pass astern, then you could crash.

Honestly, you would not believe the number of people who have boats and have absolutely NO IDEA what any of these rules are. Arraggh!


Confused? Here is a bit of a summary. Anything listed above your kind of vessel you give way to – anything below gives way to you.

  1. Vessels Not Under Command. (So thats someone who has lost their engine or steering and can’t control where they are going. You’ll also want to give way to all vessels who are at anchor and aground…)
  2. Vessels Restricted in their Ability to Manoeuvre RAM (Towing someone, big ships in narrow channels, laying submarine cables, etc)
  3. Vessels Constrained by their Draft (big boats restricted to the shipping channel)
  4. Vessels engaged in fishing (no that does not include you if you’ve got your rod over the side – but big fishing boats with gear extended)
  5. Sailing Vessels – while actually sailing – give way to boats on starboard tack and boats on the same tack to leeward.
  6. Power Driven Vessels – anything motoring along gives way to anything approaching on their right hand side
  7. Sea Planes

15 thoughts on “COLREGS, Lights & Sailing at Night

  1. Very cool post, thank you for sharing. It is fun comparing these regs to the regs here in the US. For the most part they are the same however here each State has slightly different rules regarding small boats.


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  6. My understanding of colregs was that no vessel ever has “right of way” vessels are either “stand on” or give way. The stand on vessel does not have a right of way but an obligation to hold course and speed to enable the give way vessel to manoeuvre that craft to avoid collision.

    Further should the stand on vessel become concerned about collision they are obliged to take avoiding clear manoeuvres at an appropriate time or not a last second manoeuvring risk laden turn off speed change.

    Long story short “I had right of way” won’t wash in maritime court.

    Liked by 1 person

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