tides / guides
I think the best place to start is to find a good set of tide tables for the region you''ll be sailing in. Admiralty Charts in the UK is a good source for worldwide charts, current and tide info--www.hydro.gov.uk.
And do an internet search on your subject. I did a google search on <tides currents baltic> and got a lot of interesting reading.
Bear in mind there''s 2 things you need to get out of tidal charts: currents and water depth. Currents are important for navigation and timing of routes, while water depths are important for planning anchorages and times for passing through shallow areas. Of the 2, understanding the currents is, in my opinion, the more important issue from a planning standpoint. As you plan your route, make sure you take into account the expected current and its effect on your speed over ground. And don''t overlook the effects of strong wind blowing against strong currents--you can plan for unsettled or even dangerous waves in those conditions.