Sea facts Charting the history of sailing maps

♦ Admiralty Standard Nautical Charts comprise about 3,500 hard copy charts and 14,000 digital equivalents.

♦ The charts are published by the UK Hydrographic Agency, which is the successor of the Admiralty, which began producing the charts in 1800.

♦ Alexander Dalrymple is the first official hydrographer. His hypotheses helped lead to the discovery of Australia.

♦ Sailing students learn to navigate using paper maps.

♦ Updates of paper charts need to be regularly published to take account of new hazards such as wind farms.

♦ Admiralty charts include information on depths, coastline, buoyage and underwater contour lines.