TidePush answers one question: when is it best to leave? Give it a route, your boat’s cruising speed and a range of dates, and it returns the cast-off time that makes the tidal current work for you — with the window either side of it in which the day still works, and a plain statement when no departure works at all.
It covers Puget Sound, the San Juan and Gulf Islands, the Strait of Juan de Fuca, the Strait of Georgia, the Sunshine Coast and Desolation Sound.
The planner needs JavaScript because every passage is integrated on your own device rather than on a server — which is also why it keeps working offline once installed. These pages are plain HTML and need nothing: