@roger,
we use the tidal charts in any marine area to compute our "bottoms". I can pilot into relatively shallow area by pulling down the tidal information n use the "rule of 12's " to figure out whether its safe for me in a falling tide. This is especially true in the Chesapeake around towns like Rock Hall or Some o the drowned islands, and especially in the Bay of Fundy where the ultimate outgoing tides can leave us on a beach.
Course, onc we get in (if by the skin of our bottom paint) we may have to wait another half lunar day before we can get out again.
Which always brings up another question ,which tidal clock is the best