I've made mention I don't know how many times, that I do not book a single charter without consulting my Florida Sportsman Tide Planner Book.
A good fisherman should "study" our tides like they are taking a self guided college course in NE Florida tides. Because everything you do is dependent on it, when you go fishing.
Being one of those "study like it's a college course" kinda anglers. I ran across a portion of the Marine weather website that I look at that was really and "eye opener".
Tides on that free card at the bait shop, in the newspaper, , on your tide watch or whever is a "PREDICTED" tide.
Reality is it's not a perfect science. Like fishing!
Variables that change the way that tides flow up and down, are barometric pressure. The atmosphere weighing more or less each day pushes down on the water, squeezing it out as if you pour water on your counter top at home, and then take your hand and lay it on the water and push down. The water will squirt from under your hand. Same thing...barometric pressure forces the water to move horizonally, beyond the control of the moon. Wind direction, another consideration. We've all seen how fast the tide flows as it ebbs at the jetties when there's a hard west wind. The tide or at least water on the surface is hauling butt!
Well, here's proof that the tides aren't always what they were predicted to be.
St. John's River Operational Forecast System (SJOFS)
SISTERS CREEK/ST. JOHNS RIVER
Here you can see the "now cast" versus the predicted is quit different.
Here's another graph that shows actual and predicted/forecasted.
Historic Tide Data - Mayport Bar Pilot Dock.
If you want to have a nice log book full of tide predictions for the whole state. I highly reccomend the Florida Sportsman Tide Planner. Found at local bait shops, and Strike Zone. I get a new one every Thanksgiving. So I'm ready to start the new year off right.
Trivia Question Answer: Tides DO NOT go in and out. They "rise and fall". The by product, I guess you could say is that they create allot of current in a place like the dreadged to the hilt, St. Johns River. So when I talk about the fast or slow current in the river, while fishing, I'm refering to the strength of the tide. Actual, or being helped by other earthly forces, like wind and barometric pressure etc.
Here's some "tide animation" to help you out:
More helpful "pictures" if you're interested, with really nice simple explanations.