Finnish charts

Updating of nautical charts

Safe navigation requires an updated nautical chart. In every chart or chart folio the Edition No is given and also the latest Notices to Mariners (issue and date) according to which the chart edition has been updated (Corrected up to). Only the latest edition of a chart is valid – older chart editions should not be used for navigation. There is a list of the current chart editions on the Finnish Transport Agency’s website, at the address www.fta.fi.

Coordinate systems, projections and depth

The coordinate system of the Finnish charts is either EUREFFIN or KKJ, depending on when the chart has been published. The coordinate system of the modernised charts, EUREF-FIN, is based on the international maritime standard WGS 84, the coordinate system also used in e.g. GPS satellite navigation. EUREF-FIN and WGS 84 coincide so closely (precision 1 m) that the difference is in practice negligible.

Coordinates according to the national geodetic chart coordinate system KKJ that is being replaced can still be found. The International Spheroid INT 1924 (Hayford 1910) constitutes the reference ellipsoid in the KKJ system. The KKJ and WGS 84 systems are not directly compatible and they differ about 0,00’ – 0,02’ in latitudes and about 0,18’ – 0,23’ in longitudes, depending on the area.

The Finnish charts are, with only a few exceptions, drawn using the Mercator projection. The projection and coordinate system that have been used are given separately in each chart.

On Finnish charts depths are given in metres. In sea areas depth calculations are based on the Mean Sea Level. In inland waterway charts the plane of reference for depth indications is given separately on each chart and it usually corresponds to the Low Water Level in the watercourse.

Nautical Charts 2012 brochure and index in  PDF format