Shore Diving: Tides and Currents

[TMHeimer]

I am very familiar with Fort Pickens and all if those "inlet" dives on the Gulf. Of course, the currents at the inlets are extremely strong because they're filling and emptying huge bays. For these places, you want to try to begin the first of two dives maybe a half hour before high tide, then you may finish about when the the slack at high tide begins to turn. It's better to error on the side of the still incoming tide rather than risk winding up in Cuba just before it becomes totally legal for Americans.... The (Eastern) Gulf tides of course are diurnal (they go from high to low once daily as opposed to the East Coast tides that do this twice daily). The tides at times can be somewhat off from what the tide charts say. And there is a funny day or two here and there when there is only like 3 hours between high and low as they magically "flip around". Of course, you can reverse your plan to dive at slack low tide and have poorer viz because of all the crap leaving the bays. In Jan. and Feb. there are very few high tides during daylight and for some reason almost NO low tides then. I believe inlet tides have the same problems pretty much anywhere. The tides at Perdido Pass (Alabama Point) are really nasty--I was caught in one once and the change was sudden. Of course, you can avoid all this by just diving right in the Gulf or bays, but these sites (especially the bays) are nowhere as interesting as the inlets.


On the East Coast, which has 6 foot tides as opposed to the1-2' Gulf ones, it doesn't matter too much what you do except for two things--One is check which way the water is actually going. Sometimes it's going sideways due to the formation of the land (Long Island Sound, for example). The other is if it's just a straight in and out direction of water, be aware that if the tide is ebbing you're getting a slight (really not noticible) push when leaving shore--when returning against it you may very well notice you are fighting a slight current. So, it's best not to wander as far out in this situation.

The West Coast and the West side of the Gulf of M. have "mixed" tides--I haven't experienced that.

 

[MXGratefulDiver]

Thank you. That seems to be the overwhelming thought by everyone and I plan on doing that before every shore dive I do.
However, is there some sort of standard for dealing with tides to get an idea on the difficulty or intensity of a tide current, etc. in regards to tidal range, current speed, and time of tide (high/low/inbetween)?
Surely there is some standard protocol out there from one of the dive organizations (PADI, NAUI, SSI, etc) on a website, a book, or in someone's personal experience. I can't seem to find any general rules.The closest I found was this website: Tidal Currents - Diving Nelson Bay
Any opinions on the info presented there?
Also the tide times, tidal range, and tidal current I got from here: Tide/Current Predictor

There aren't any standards because how diveable a site will be depends on far more than simply what the tides are doing.

Where I live most of the diving is from shore. Some sites can be dived at any time, regardless of how big the exchanges are. Other sites can only be dived on very small exchanges, and in some cases only during a very short window between exchanges. And still others during certain types of exchanges ... for example, diveable on a moderate flood, but not at all on an ebb. And it doesn't always depend on the size of the exchange.

Also keep in mind that topography plays a huge role. At some sites (for example) an ebb may create eddies or downcurrents due to slope, points of land (bays, for instance), or obstructions such as jetties, while the same site may not see the same impacts by a flood. And then there are corrections ... the time between when the tide switches and when the water actually stops moving in one direction and switches the other way. In some sites, "slack" can lead or lag the actual tidal switch by up to or over an hour ... while at other sites it may occur almost simultaneous with the tidal high or low. And in some cases that will depend on how large the tidal exchange is, and over what duration.

This is why people are talking about the importance of local knowledge ... because predicting slack is sometimes analogous to predicting the weather. And sometimes even when you think you know what it will do, you turn out to be wrong.

... and that's why they call 'em "predictions" ...

... Bob (Grateful Diver)