San Francisco Tides

Time Event Value Units
12:17 am Max Flood 2.8 kt
01:44 am High Tide 6.43 ft
02:32 am Slack
06:06 am Max Ebb -4.6 kt
08:24 am Low Tide -0.95 ft
10:30 am Slack
01:28 pm Max Flood 2.8 kt
03:29 pm High Tide 4.58 ft
04:33 pm Slack
07:12 pm Max Ebb -2.2 kt
08:07 pm Low Tide 2.33 ft
10:06 pm Slack
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?