Reference Zone - General Marine GI

A brief explanation of Chart Datum and tidal levels.

A brief introduction to Coordinate Reference Systems

A brief explanation of the differences between surveyed depths and those that are depicted on a nautical chart. This has been produced by the Seabed Data Centre at the UK Hydrographic Office and is published here by SeaZone Solutions.

Introducing the Vertical Offshore Reference Frame (VORF) project, which will provide the capability to seamlessly join land and sea surfaces across the shore, extend the knowledge of vertical datums and reference surfaces offshore and enable the transformation of height and depth between a number of vertical datums and reference surfaces.