San Francisco Tides

Time Event Value Units
12:24 am Slack
03:12 am Max Flood 2.1 kt
05:21 am High Tide 5.08 ft
06:24 am Slack
09:48 am Max Ebb -2.2 kt
11:25 am Low Tide 2.38 ft
01:54 pm Slack
03:36 pm Max Flood 0.8 kt
04:34 pm High Tide 3.85 ft
05:42 pm Slack
09:30 pm Max Ebb -2.2 kt
10:44 pm Low Tide 1.29 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?