Admiralty charts to be transferred to WGS 84 datum, says U.K. Hydro Office

Sea Technology, Mar 2000

The United Kingdom Hydrographic Office (UKHO) will start a three-year programme this month to transfer 310 Admiralty charts of Great Britain to a horizontal datum compatible with WGS 84 Datum.

The transfer of the remaining charts of the British Isles will follow. Currently, Admiralty charts of the British Isles are referred to several regional datums, for example Ordnance Survey of Great Britain 1936 (OSGB 36) Datum. However, navigational positions obtained from satellite positioning systems, such as the global positioning system (GPS), which are now used for navigation, are normally referred to World Geodetic System 1984 (WGS 84) Datum.

In order to enable users of GPS to plot positions on Admiralty charts, latitude and longitude shift values are currently provided so that adjustments can be applied to the positions before plotting. It would improve ease and safety of navigation if mariners did not have to apply such adjustments. Hence the transfer to a WGS 84 compatible datum.

The UKHO has consulted a wide range of chart users and there was a unanimous response in favor of transfer to a WGS 84 compatible datum. U.K. Admiralty charts will therefore in future be referred to the current equivalent of WGS 84 Datum for Europe, the European Terrestrial Reference System 1989 (ETRS 89) Datum.

Areas due to be converted by the end of June 2000 include the River Clyde; the East Coast of England from Great Yarmouth to Harwich; the Solent; and the area of the Irish Sea north and east of the Isle of Man. The eastern portion of the Bristol Channel is due to be converted by the end of the summer. The East and South coasts of England from the Wash to Plymouth, plus approaches to Liverpool, should be completed in time for the 2001 sailing season.