255 Additional guidance on chart datums and the accuracy of positions on charts

1 The Sub-Committee on Safety of Navigation, at its fifty-second session (17 to 21 July 2006), approved additional guidance on chart datums and the accuracy of positions on charts, given at annex. This guidance is provided in addition to the guidance contained in SN/Circ.213 dated 31 May 2000.

2 Member Governments are invited to bring this guidance to the attention of all concerned for information, in particular, by having them published in pertinent official nautical publications and action, as appropriate.

Annex

In some areas of the world there are charts that are based on old surveys for which there is no determined geodetic datum or the datum is imprecise. Therefore in such areas, paper charts (and thus raster navigational charts) are not compatible with GNSS navigation, and it will take some time to resolve this problem. This makes it extremely difficult to accurately plot the ship.s position obtained by the GNSS in relation to surrounding dangers on such charts. The difference in the plotted position can often be significant and could lead to a casualty or unnecessary risk in restricted waters.

Cross-checking of position using visual or radar fixing or ECDIS radar overlay can provide for the immediate detection of datum inconsistencies in electronic charts, and immediately alert the mariner on potential positional shifts required for particular charts. Some ECDIS equipment exceeds the minimum requirements of the ECDIS Performance standards, by providing such features as radar overlay.

In general, when navigating with GNSS, mariners should undertake all available measures to check the position of the ship obtained by continuous position fixing systems and plotted on any charts, such as using radar and visual observation methods.

• Informatietype: Internationaal
• Documentsoort: Circulaire niet in wetten.nl
• Toegangsrechten: Extern
• Identificatie: PUC_2040_14
• Versie: 1
• Datum beschikbaarheid: 05-10-2006
• Geldigheid van: 24-07-2006
• Wijzigingsdatum: 24-11-2016
• Titel: 255 Additional guidance on chart datums and the accuracy of positions on charts
• Organisatie: International Maritime Organization (IMO)
• Taal: Nederlands
• Thema: SN Circulars (Informative)