International agreements on nautical charts
Shipping is an international business. Mariners therefore need uniform charting principles to be able to trust and interpret the nautical charts regardless of their position on earth. To this end, several countries have agreed on using uniform symbols and other requirements for paper and electronic charts.
SOLAS: responsibility of coastal states
Coastal states are obliged to chart their home waters. This is laid down in the International Convention for the Safety of Life at Sea (SOLAS Convention) of the International Maritime Organisation (IMO).
The Hydrographic Service produces charts on behalf of the Netherlands.
Agreements on charting
Official charts and nautical publications must be understandable for international mariners. Agreements have therefore been made on format, symbolisation etc. The International Hydrographic Organization (IHO) publishes the specifications in various publications. The IHO is an intergovernmental organisation, in which national Hydrogaphic Offices cooperate to support safety of navigation.
International paper charts
Official paper charts that adhere to the IHO specifications are given a unique so-called INT number. Hydrographic Offices can use each other’s charts to make their own charts, or for incorporation into their chart series. The charts have both a national number and an INT number (in magenta).
Electronic navigational charts are linked
As opposed to paper charts, electronic navigational charts (ENCs) do not overlap. ENC-producing countries therefore cover their respective areas and make agreements with neighbouring countries about border areas.
In order to realise a consistent and coherent ENC Database, the Hydrographic Service cooperates with neighbouring HOs within IC-ENC, a partnership of ENC-producing Hydrographic Offices. Via IC-ENC, the ENCs are provided through agents, or value-added resellers.