In writing this article I start from a comment to a post a few months ago, where a reader wrote, on the subject of safety at sea, that it would be useful to publish a map of the permitted speed below the coast, in reference, I think, to the many accidents that, especially in summer, are caused by the excessive speed of boats and jet skis.
Since safety at sea is a vast subject, it is important to remember and keep in mind that it also, and above all, depends on correct behaviour, education, common sense and, of course, respect for the rules.
The world we are addressing, and in which we ourselves move, is the world of pleasure boats, both sailing and motor boats, and we know that there are no speed limits imposed on boats during navigation, except in protected marine areas, port basins, harbour entrance channels, coastal strips and all those areas for which the local ordinances of the harbour master's office give specific indications in this regard.

That is why it is always necessary to refer to and check portulans, which are obviously up-to-date. The result then is that, due to this complexity of scenarios and regulations, there are no 'maps' that provide us with the speed limits to be observed in a simple and schematic manner.

But... there are rules that must guide us in our behaviour when at sea. It is an actual regulation, theInternational Regulations for Preventing Collisions at Seaotherwise known as COLREGS (in Italian International regulation to prevent collisions1 at sea or RIPAM).

In particular in the Rule No. 6 we are really talking about speed:
Security Speed
Each ship2 must always proceed at a safe speed so that it can, act appropriately and efficiently to avoid boarding and be stopped within a distance appropriate to the circumstances and conditions at the time. The following factors should be among those taken into account when determining safe speed:
(a) For all ships:
(i) visibility:
(ii) traffic density, including the concentration of fishing vessels and other types of vessels;
(iii) the manoeuvrability of the vessel with special reference to stopping distance and its evolutionary qualities in the conditions of the moment;
(iv) at night, the presence of background lights such as those from coastal lights and the glow of one's own lights;
(v) the state of the wind, sea and current and the proximity of dangers to navigation;
(vi) the draught in relation to the existing seabed in the area.
(b) In addition, for vessels equipped with radar:
(i) the characteristics, efficiency and limitations of the radar equipment;
(ii) the limitations imposed by the scale of the radar in use;
(iii) the effect on radar detection of weather conditions and other sources of interference;
(iv) the fact that small units, small icebergs and other floating objects may not be detected by radar;
(v) the number, position and movement of vessels detected by radar;
(vi) the increased probability of sighting when radar is used to determine the distance to ships or other nearby objects.

As you read, there is no mention of a maximum speed limit, but of SAFETY SPEED, a more aleatory concept, but one that already implies a responsible attitude on the part of those steering the ship. The rule does not provide us with limits or numbers to stick to, but it does provide all the necessary elements to adapt speed to the many situations we may encounter.

Citing COLREGS, we feel it is also important to quote Rule No. 5, which is of fundamental importance when speaking of safety.

Rule No. 5:
"Every ship must maintain an appropriate visual and auditory lookout, using all means available adapted to the circumstances and conditions of the moment so as to allow a full assessment of the situation and the risk of boarding".

Safety therefore comes first and foremost, as mentioned in the beginning, from compliance with the rules, but also from responsible behaviour on the part of those who steer a vessel. Whether sailing or motoring, it is important to set up watch shifts day and night so that there is always a crew member in charge of frequently performing the classic 'horizon watch', checking with the eye (visual lookout service) all the sea space around the boat and without underestimating the importance of hearing. The rule also tells us to use all available meansso keep the radar on in situations that require its use. Remember that AIS is an automatic tracking system used in the naval sector, in aid to radar systems in order to avoid collisions between vessels in navigation.

They are rules, but they are good basic rules for navigating with respect for one's own safety and that of others.

  1. In the Italian translation the term 'collision"which means collision, has been translated as "boarding"; in this translation, the meaning of the term is therefore to be understood not as "voluntary approach", as in the more common use of the term, but as, precisely, "Collision, collision between ships, whether by accident or by error of manoeuvre, and thus by non-application or misapplication of international rules, and those arising therefrom in national legislation "(Source: Treccani online https://www.treccani.it/vocabolario/abbordo/) ↩︎
  2. It is important to make a clarification: in indicating to whom the rule is addressed, the text speaks of "ship"as stated in Rule No. 3 letter a by Colreg himself, we read: 'The word 'ship' designates any type of vesselincluding non-displacement and seaplanes, used or capable of being used as a means of transport on water“. ↩︎

Original version of COLREGS Rules No. 5 en.6

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 of the risk of collision.

Rule 6 - Safe Speed Every vessel shall at all times proceed at a safe speed so that it can take proper and effective action
to avoid collision and be stopped within a distance appropriate to the prevailing circumstances and
conditions. In determining a safe speed the following factors shall be among those taken into
account:

(a) By all vessels:
(i) the state of visibility;
(ii) the traffic density including concentrations of fishing vessels or any other vessels;
(iii) the manoeuvrability of the vessel with special reference to stopping distance and turning ability in the prevailing conditions;
(iv) at night the presence of background light such as from shore lights or from back scatter of its own lights;
(v) the state of wind, sea and current, and the proximity of navigational hazards; (vi) the draught in relation to the available depth of water.
(b) In addition, by vessels with operational radar:
(i) the characteristics, efficiency and limitations of the radar equipment;
(ii) any constraints imposed by the radar range scale in use;
(iii) the effect on radar detection of the sea state, weather and other sources of interference;
(iv) the possibility that small vessels, ice and other large floating objects may not be detected by radar at an adequate range;
(v) the number, location and movements of vessels detected by radar;
(vi) the more exact assessment of the visibility that may be possible when radar is used to determine the range of vessels or other objects in the vicinity.

(Text taken from: https://www.samgongustofa.is/media/log-og-reglur/COLREG-Consolidated-2018.pdf )


The International regulation to prevent collisions at sea (also known as COLREGCOLREGsRIPA o RIPAM) is a multilateral agreement establishing rules of behaviour during navigation This convention was defined in London in 1972, but did not enter into force until 1977 (after being approved by all member states) and has 41 rules. The rules originated from a multilateral agreement between several countries called Convention on the International Regulations for Preventing Collisions at Sea.


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