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Nautical Charts and UNCLOS

Nautical charts are fundamental elements recognised by the United Nations Convention on the Law of the Sea (UNCLOS) for the accurate depiction of lines of delimitation drawn in accordance with the Convention. To this effect, coastal states must produce official nautical charts as defined by the International Convention for the Safety of Life at Sea (SOLAS).<P>

Under articles 16/2, 47/9, 75/2, 84/2 and 76/9 of the 1982 United Nations Convention on the Law of the Sea (UNCLOS), coastal states are required to deposit with the Secretary-General of the UN charts showing straight baselines and archipelagic baselines as well as the outer limits of the territorial sea, the exclusive economic zone and the continental shelf or instead of these lines, where appropriate, lists of geographical coordinates of points specifying the geodetic datum. In addition, articles 22/4, 41/6 and 53/10 indicate that sea lanes and traffic-separation schemes shall be shown on charts, and articles 5,6 and 84/1 specify that the different lines of delimitation shall be shown on charts of appropriate scales and officially recognised by the coastal state.


A chart is a very important element for the study, depiction, application and recognition of many technical and legal issues contained in the UNCLOS. It is true to say that without the existence of charts and knowledge of their technical characteristics, it is impossible to understand, interpret and present cases related to the application of this Convention. Maritime zones, baselines, internal waters, mouth of rivers, bays, harbours, ports, roadsteads, tide elevations, sea lanes and traffic-separation schemes, enclosed and semi-enclosed seas, and submarine features are some of the technical issues contained in the UNCLOS that need to be accurately presented in charts; and, in this case, the UNCLOS refers to nautical charts.

The definition of ‘nautical chart’ that must be used by the coastal states in connection with the UNCLOS is contained in Regulation 2, paragraph 2, of Chapter V of the SOLAS, which states that a ‘nautical chart is a special-purpose map or a specially compiled database from which such map is derived, that is issued officially by or on the authority of a government, authorised Hydrographic Office or other relevant government institution’. This definition covers the paper and electronic nautical chart (ENC), for the production of which the appropriate resolutions and recommendations of the International Hydrographic Organization (IHO) should be followed.

As technology progresses, the IHO is responding to the UN Division for Ocean Affairs and the Law of the Sea’s (UNDOALOS’) request to develop a data model/technical guide on the basis of a standard that contains a description of the collection, storage and dissemination of data, in order to ensure compatibility between the digital formats used by the UNDOALOS, the ENC used by the IHO and electronic systems developed by other organisations. The IHO, which has been recognised by the UNCLOS as the competent international organisation for hydrographic issues, can provide any support needed to coastal states in producing paper nautical charts or ENCs, needed not only for issues affecting the safety at sea and the protection of the marine environment but also for the applications of the UNCLOS.

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