San Francisco Tides

Time Event Value Units
01:52 am Max Flood 2 kt
03:17 am High Tide 6.05 ft
03:57 am Slack
07:41 am Max Ebb -3.9 kt
10:28 am Low Tide -0.61 ft
12:43 pm Slack
03:32 pm Max Flood 2.1 kt
06:09 pm High Tide 4.23 ft
06:50 pm Slack
09:22 pm Max Ebb -1.6 kt
10:16 pm Low Tide 3.19 ft
What day is the longest?
Why are there 2 tides per day?
Why doesn't Slack = High/Low Tide?
Why can you ride a flood but not an ebb?