A map built for safe passage, showing depths below chart datum, contours, hazards, seabed type, lights and buoys, and the coastline and landmarks needed for pilotage. Charts exist as paper and raster charts and as electronic navigational charts. For many vessels a chart is a legally required document, and keeping it corrected with notices to mariners is a basic seamanship duty.
Nautical chart still shows 7 metres over the bar, our survey says 5.4, so it goes in as a DtoN.
Also heard as
- chart
- navigational chart
- paper chart
Related terms
ENC
Electronic navigational chart: an official vector chart database used in ECDIS, built from objects with attributes.
Sounding selection
Choosing which surveyed depths appear on a chart so the shoalest water is always shown.
Notice to Mariners
An official bulletin of chart corrections and navigational warnings, issued regularly to keep charts current.
Chart datum
The low-water level from which charted depths are measured, set so actual depth is seldom much less than shown.