San Francisco Tides

Time Event Value Units
12:17 am Max Flood 1.6 kt
01:13 am High Tide 5.83 ft
02:10 am Slack
06:10 am Max Ebb -3.8 kt
08:18 am Low Tide -0.93 ft
10:51 am Slack
01:48 pm Max Flood 2.6 kt
03:56 pm High Tide 4.53 ft
05:06 pm Slack
07:39 pm Max Ebb -1.8 kt
08:06 pm Low Tide 3.32 ft
10:32 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?