Tidal Question

[thedirtyjobs]

OK, here i go again....yes, another rookie question. Last night i got to the Marina (Worlds Fair on Flushing Bay) right around low tide. And I couldn't believe my eyes! The water was soooooo low. Maybe 2 feet at the first slips. By my boat, maybe 3. It was not like this last year when i was there.

Could this have been a fluke low tide or should i be concerned?

And now for the really stupid question. Let's say low tide is identified as 6:30pm. It pretty much happens right about then right? Goes out pretty quick and comes in pretty quick. Its not a gradual thing that happens over several hours...right?

God i have a ton to learn! I have to find a way to get you guys some beer!

later,
dan

 

[mintregila]

First, north shore tides are extreme in the difference between high and low. At my dock, it is as much as 6 feet.

I believe we also just had a moon tide with higher highs and lower lows. If you take a look at the tide chart for City Island, you will be pretty close. In addition, you will see that there are 2 highs and 2 lows each day with approx 6+/- hours for a complete change.

Lastly, the direction of the wind can also have an effect on tide hight by either helping to push the water in or out.

 

[Radiowaves]

quote:

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Originally posted by thedirtyjobs

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In addition to what Mark states, most all cases it is gradual for example if the low tide was at 5:05AM then it will begin to slowly rise until the high at 10:24AM. There usually is a period of slack tide before it begins to move the other way. In high current areas you can see the movement much easier and appears to be moving quickly. But in reality, there is usually about a 6 hour in tide and then and out tide with a slack tide in between.

Tide Babylon

MON 5 Low 5:05 AM
5 High 10:24 AM
5 Low 5:04 PM
5 High 10:42 PM

To make things more complicated there are moon tides and at different times of the year you will have extreme highs and lows. There are times where it is low and lower between the tide changes and also high and higher. A few weeks ago it seemed like the bay was draining out. And this weekend it was higher than normal near Babylon. But in any event there is a 6+/- hour change in tides coming in or out. Also there will be about an hour +/- change each day moving forward each day - i.e. For Babylon on Tuesday 5/6 the low is 5:57AM.

Brad

 

[ronp]

Dan, as far as how quickly the tide rises or falls, there is this rule of twelfths that applies in most places. Although, there are places in the world where things happen very differently due to coastal geography. Here on the south shore, this seems pretty accurate to me. I'm not familiar with north shore behavior but I suspect it is similar there.

What you see here is that about half the rise or fall happens in the 2 hour period in the middle, that's when most of the action is. Very little happens an hour before or after a low or high tide, which is why people call it slack tide as Brad said above.

TIDES: Estimating tide rise and fall. The simplest rule of thumb for the guestimation of the height and speed of flow of the tide is the twelfths rule:

1 Hr. after low/hi water 1/12 of the tide height will rise/fall
2 Hr. after low/hi water 2/12 of the tide height will rise/fall
3 Hr. after low/hi water 3/12 of the tide height will rise/fall
4 Hr. after low/hi water 3/12 of the tide height will rise/fall
5 Hr. after low/hi water 2/12 of the tide height will rise/fall
6 Hr. after low/hi water 1/12 of the tide height will rise/fall

 

[thedirtyjobs]

Thanks guys! I'm learning a tremendous amount from all of you! Then i get to look smart when guests on my boat ask me a question...hahaha!

Much appreciated,
dan

 

[HOGAN]

The earth is also at one of it's closest points to the moon, so tides will be higher and lower than normal.