That it is, and what is GNSS- Satellite navigation
- They are nautical publications published in Spain by the hydrographic Institute of the Navy (Cadiz) and include all the Spanish coasts.
- The English Admiralty published all over the world.
- In these books are interesting data for seamen, in terms of recognition of the coast.
- On their front pages, there are a few summaries of winds, weather and other weather phenomena in coastal regions, as well as magnetic disturbances, Maritime Rescue Co-ordination Centre, etc…
- On the following pages come neatly reflected how much data it presents the coast and nearby, as well as ports, currents, soundings, anchorages, dangers, beacons, etc… interspersed with illustrations from drawings in different paragraphs or panoramic photographs.