I notice you are in Kent. If you are really interested go the National Maritime museum and ask in the library to be shown the charts and pilotage info carried on a ship of Nelson's period ... they'll happily show you. It's amazingly little. Of course they did keep their own notes and share information and the ability to draw a coastline was considered part of a midshipman's education.
Not just Nelson. Much of the success in repelling the Spanish Armada came from a knowledge of tidal streams and eddies. At one point one of the Spanish captains is said to have complained that the English must have been in league with the Devil, because they were able to sail against the tide. In fact, they were using a tidal eddy like that near Portland Bill.
Day Skipper stuff, really. "Able to skipper a small boat in familiar waters by day". And boy, were they familiar with the waters!