The Instituto Hidrográfico do Portugal has online real-time tide-tables for major ports, including Lagos here:
http://www.hidrografico.pt/previsao-mares.php
Make sure you have javascript activated and click on the name of the Port for which tables you require.
Portuguese Lesson:
Preia-mar = High Tide
Baixa-mar = Low Tide
Using the calendar feature above the map you can track back online until 1999.
