Introduction and background


The purpose of IHO Publication C-55 is to provide base data for governments and supporting international organizations as they consider the best means by which to implement responsibilities set out in Chapter V, Regulation 9, of the Safety of Life at Sea (SOLAS) Convention. It also informs IHO input to the United Nations’ Global Maritime Assessment.



In 1970 the United Nations (UN) began a process of evaluating the current status and progress of hydrographic surveys and bathymetric charting worldwide. From the outset regional cooperation was encouraged. The IHO was tasked to undertake detailed study. This was informed by a series of questionnaires issued to coastal States during the 1980s. Despite a disappointing response on each occasion, an analysis was conducted and reports were published. The sequence culminated in the production of the first edition of C-55 (S-55) (1991), which was also promulgated by the UN in Volume XXII of World Cartography (ST/TCD/19 New York 1993). This was based on data for 46% of maritime nations and areas.

A second edition of C-55 (S-55) was issued by the IHO in 1998, based on information collected in 1995-96. Again there were very significant gaps in the supporting database. Information was available for only 47% of maritime nations and areas.

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Last modified: 14/01/2021 - 14:54