COLREG In Easy Language (Rule 2,5,7 & 8)

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Collisions are among the most high profile of all maritime accidents. The number of collisions and their cost (personal and financial) has increased in recent years and “human error” seems to be the only common factor.

Collisions should not happen but they do; sometimes with disastrous consequences.If the regulations are followed to the letter, then a collision should never occur.

The best lesson you can learn here is to acknowledge the watch keeper’s responsibility to identify a “risk of collision” and to take all necessary steps to avoid or to minimize that risk.

This is not a textbook of the COLREG. We’ll discuss the rules that are most often misinterpreted and misapplied. We’ll try to demonstrate how those rules fit together and how the interpretation and application of each of them can be influenced, sometimes wrongly, by the vast mass of information now available from electronic aids to navigation.


(a) Nothing in these Rules shall exonerate any vessel, or the owner, master or crew thereof, from the consequences of any neglect to comply with these Rules or of the neglect of any precaution which may be required by the ordinary practice of seamen, or by the special circumstances of the case.

(b) In construing and complying with these Rules due regard shall be had to all dangers of navigation and collision and to any circumstances, including the limitations of the vessels involved, which may make a departure from these Rules necessary to avoid immediate danger.

Rule 2 is a vital rule that is often misunderstood.

It is different from the majority of the COLREGs because it does not tell you what to do or when to do it. Instead, Rule 2 highlights the fact that you are responsible for your actions. You are the one who has to make the immediate decision on what to do in order to comply with the rules.

SMS may tell you when to call the master or what to do if the visibility reduces, but is the Rule 2 that makes you responsible to your fellow crew and to the ships around you.

Your responsibility is not only to follow COLREGs – you are also responsible for doing everything necessary to avoid the risk of collision and the dangers of navigation.

Rule 2(a) requires you to follow both the rules and “the ordinary practice of seamen”. This means that you must always use common sense.

Rule 2(b) is often misunderstood so read it carefully. It only allows you to depart from the rules if that is the only way to avoid an immediate danger. But, in almost every situation, it is the proper application of the rules that will keep you out of that danger. Rule 2(b) is never a justification for not following the rules properly.

Rule 2 allows no excuses.

Rule 5: LOOK-OUT

Every vessel shall at all times maintain a proper look-out by sight and hearing as well as by all available means appropriate in the prevailing circumstances and conditions so as to make a full appraisal of the situation and the risk of collision.

Rule 5 is short but it has two vital elements:

• You must pay attention to everything – not just looking ahead out of the bridge windows but looking all around the vessel, using all your senses and all personnel and equipment available to you. There must always be someone looking-out.

• You must use all of that information continuously to assess the situation your vessel is in and the risk of collision.

The requirement to “maintain a proper look-out” includes:

•Looking and listening – maintain a continuous watch by sight and by hearing, both inside and outside the wheelhouse.

•Looking means looking out of the windows, all the time.

•Using ECDIS – the prime function of ECDIS is to help you be sure that your ship is not moving into danger. Its other functions are useful but you must not get distracted by them.

•Using ARPA – you must be aware of the effects of clutter, of small targets and the range and limitations of the set.

•Using a radio – you must listen to what is going on around you but you must always think carefully before calling other ships on VHF. It always takes more time than you think and it may cause delay and confusion.

•Monitoring sound signals – ensure you can hear what is going on outside the wheelhouse. Be aware of the effect of keeping a closed wheelhouse and of distracting noises inside it.

•Using a depth indicator – frequently and systematically monitor the water depth beneath your keel. The seabed is often the nearest point of danger.

•Avoid distractions such as wheelhouse and deck lights, other people, navigational records and routine paperwork, including chart corrections.

•Always remember that you are on the bridge watch to keep the ship safe, as set out in Rule 2 on responsibility.


(a)Every vessel shall use all available means appropriate to the prevailing circumstances and conditions to determine if risk of collision exists. If there is any doubt such risk shall be deemed to exist.

(b)Proper use shall be made of radar equipment if fitted and operational, including long-range scanning to obtain early warning of risk of collision and radar plotting or equivalent systematic observation of detected objects.

(c)Assumptions shall not be made on the basis of scanty information, especially scanty radar information.

(d)In determining if risk of collision exists, the following considerations shall be among those taken into account:

(i)Such risk shall be deemed to exist if the compass bearing of an approaching vessel does not appreciably change;

(ii)Such risk may sometimes exist even when an appreciable bearing change is evident, particularly when approaching a very large vessel or a tow or when approaching a vessel at close range.

Rule 5 on look-out and Rule 7 are closely linked. Under Rule 5 you must use all available means to collect information on the situation around you (look-out) and under Rule 7 you must use that information continuously to assess the risk of collision. To assess the risk of collision you must continuously ask yourself:

1)  Is a collision possible, because of the action (or inaction) of any vessel in the vicinity – including your own vessel?

2)  Is a collision probable? If so, the risk of collision is already here and you need to act urgently.

How to assess?

1) Look and listen – as with keeping a look-out, you must use all the information and equipment available to determine the risk of collision.

2) Use the compass to check the bearing of approaching vessels, and do this regularly. A steady bearing indicates the risk of collision but a risk of collision may exist even with a bearing change, particularly at close range and with large vessels.

3) Use radar:

a) With ARPA, use relative vectors to determine the risk of collision.

b) Is the target passing ahead or astern at safe distance or you are going to collide? Remember the primary information you need to answer these questions is relative information.

c) Do not trust ARPA to give you an accurate CPA. Take 0.5 nautical mile off each indication to be safe and, if the CPA is already 0.5 nautical miles, then assume a risk of collision exists.

d) Do not rely on a change of bearing as an indicator of clearance. As a target ship approaches, its change of bearing should accelerate significantly. If the change of bearing does not accelerate then there is a risk of collision. 

DO NOT RELAX!! Keep monitoring the situation until the target ship passed and clear.


(c) If there is sufficient sea-room, alteration of course alone may be the most effective action to avoid a close-quarters situation provided that it is made in good time, is substantial and does not result in another close-quarters situation. (e) If necessary to avoid collision or allow more time to assess the situation, a vessel shall slacken her speed or take all way off by stopping or reversing her means of propulsion.


As soon as you identify a risk of collision, you must identify the correct action to avoid collision to ensure that the vessels will pass at a “safe distance”. You should take that action to avoid collision as soon as it is appropriate to do so. Action to avoid collision should always be:

a) positive – make a big alteration of course and/or speed

b) made in good time – which means early

c) seamanlike – do not make the situation worse for any other ship in the vicinity, assess what they may have to do

d) easily seen by other ship(s) – avoid a series of small alterations of course and/or speed.

Remember, a substantial alteration made early is better than a very large alteration made late. The closer you are to the other vessel the greater the risk of collision, you’ll have less options available and the more you will have to do to pass at a safe distance. Small alterations of course and speed are also dangerous; they do not often solve the problem and they do not give the other vessel a clear indication of what you are doing. You should confirm your action to avoid collision by monitoring the change in CPA. Keep taking compass bearings and checking the situation until the risk of collision is over. And always remember your engine – if your ability to alter course is constrained then slow down or stop. 


a) If the COLREGs require you “not to impede” or “give way” to another vessel, then you must take early action to make sure risk of collision does not develop.

b) If you are “not to be impeded” or “stand-on” vessel, then you must always be prepared for the “give-way” vessel not to take action. If a risk of collision develops, you will have to act – remember the caution in Rule 2 on responsibilities and your continuing responsibilities in Rule 17 on action by the “stand-on” vessel.

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