San Francisco Tides

Time Event Value Units
02:30 am Max Ebb -3.6 kt
03:54 am Low Tide 0.15 ft
06:12 am Slack
09:00 am Max Flood 3.1 kt
10:38 am High Tide 5.8 ft
11:48 am Slack
02:54 pm Max Ebb -3.6 kt
04:28 pm Low Tide 0.69 ft
06:42 pm Slack
09:18 pm Max Flood 2.7 kt
10:49 pm High Tide 5.63 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?