Slack Tide?

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tonaskai

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:06: How do you read a tide table for slack tide? and when is it best to dive? can anyone help?

Thanks
 
Generally (but certainly not always), you'd like to dive just after high high (or just high) tide is reached. I think slack water here lasts between 15-45 minutes, and then starts the ebb (but slowly). High high tide gives you the most water, and little movement (it's slack). The worst times to dive (depending on your situation) is at low tide, or (if you're not depth limited), around the middle period between high/low tides. That's usually when the most water is moving, and constrained or otherwise high tidal amplitude regions may have dangerous or at least annoying currents.
I may be explaining this badly. Someone else I'm sure will be by and articulate it better. We only have a 18 inch tide in Texas.
 
archman:
Generally (but certainly not always), you'd like to dive just after high high (or just high) tide is reached. I think slack water here lasts between 15-14 minutes, and then starts the ebb (but slowly). High high tide gives you the most water, and little movement (it's slack). The worst times to dive (depending on your situation) is at low tide, or (if you're not depth limited) more commonly, around the middle period between high/low tides. That's usually when the most water is moving, and constrained or otherwise high tidal amplitude regions may have dangerous or at least annoying currents.
I may be explaining this badly. Someone else I'm sure will be by and articulate it better. We only have a 18 inch tide in Texas.

18 inches? I thought everything wa BIG in Texas. :eyebrow:

hehehe

Gary D.
 
Gary D.:
18 inches? I thought everything wa BIG in Texas. :eyebrow:

HOW did I not see that coming... :smileysto
 
Gary has a point, Arch. :wink:

BTW, a definition of slack tide or slack water is when the velocity of the tidal current is at or near zero. This usually is the time just before and just after high OR low tide. Beware though, in some other locations, slack tide may be near the midpoint between high and low tides.

Diving is best at slack tide unless you are planning a drift dive. Fighting currents is no fun.
 
But those are 18 TEXAS SIZED INCHES... so be real careful there pardner!

The times for high and low tides are just that... when it is highest and when it is lowest. It does not vary by location. The flow of water is almost always greatest midway between high and low, with the flow stopping completely at high and low tides. If you figure in the acceleration is like a bell curve, then you start to get an idea of how this is working.

High tides are usually the clearest... the basin has been filled with clearer water from the ocean. Low tide usually has less visibility as the sediments from the tidal basin are washed out to sea.

Consequently the best time to dive near shore is shortly before the high tide peaks. This way you get the benefit of slow, slack and then slow water flow again.

Remember when you plan your dive, to try and make allowances for any vagaries you might encounter. Choose quite a few exit points so that you will not find yourself in trouble should a long shore current (or the like) alter the way you thought the tide would react.

BTW, it is always advisable to watch the tidal currents for a cycle or two in an unfamiliar setting.
 
Zippsy:
Beware though, in some other locations, slack tide may be near the midpoint between high and low tides.

Where does it do that? I thought according to the "rule of twelfths", tidal flow was highest smack between tides.
 
I haven't a clue where it does this. I always followed exactly what Pete said above until I had to look up the term a few weeks ago for something else. If I recall collectly, the site where I found the quote about the "midway between high and low tide ... in some locations" was the National Oceanic and Atmospheric Administration. I figured they knew more than I did. I'll try to find a link again.
 
I think this is the site: http://www.csc.noaa.gov/text/glossary.html The NOAA Coastal Services Center in South Carolina seems to have borrowed the glossary from the Washington State Department of Ecology. They could be wrong but a good friend once swore to me that if it's on the internet, it must be true!
 

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