Tide tables

[Miller]

This old mountain boy needs a little help with tide tables. I’m thinking if low tide is 6:46 AM . High tide is 12:59 PM . That during this time is when the tide would be coming in. That’s when to do the shore dives. Is that right?

 

[mike_s]

it all depends on where you are diving.

If you're diving an inlet/pass, then "High slack tide" is the best time typically to dive it.

but some other locations it might be different. High slack tide means the minimum amount of water movement and usually the area has sucked in clear water instead of brackish bay water.


As for when High-tide and low tide are.... it changes every day. best to consult a tide table.

perhaps www.saltwatertides.com or another chart.

 

[String]

High water slacks often have better visibility especially if diving around estuaries/river outlets and so on.

Its worth noting however that slack water doesnt always follow local high water. Also tide tables are for specific sites and just moving 3 or 4 miles away can have a difference of over an hour.

Loads of internet resources on tides to read. Things like spring, neap and so on are worth understanding.

 

[cdiver2]

This old mountain boy needs a little help with tide tables. I’m thinking if low tide is 6:46 AM . High tide is 12:59 PM . That during this time is when the tide would be coming in. That’s when to do the shore dives. Is that right?

To get a grasp on tides.


Several broad and general premises must be acknowledged before anyone can possibly begin to understand the intricacies of tides

The first thing we have to understand is the general movement and intensity of the tides are controlled by the sun and moon, particularly the moon. The next thing we must comprehend is tides are the movements and levels of water. It’s also important to grasp that water is a liquid and can bend and move in different directions at the same time.

Finally, we must accept there are other factors (wind direction and speed) that can’t be plotted for more than a few days in advance and can affect the timing and level of tides.

Once we have a working grasp of these controlling factors, we can begin to understand tide tables are a list of predictions of tidal movements and levels that are based primarily upon the moon’s phases and the positioning of the earth in relation to its orbit around the sun and the moon’s orbit around the earth.

These predictions are usually extremely accurate, but there are unforeseen and unpredictable secondary factors that can alter the exact timing, flow and water levels of tides during any given day.

At the North Carolina coast, tides are pretty consistent in
12 1/2-hour cycles. That means within roughly 12 1/2 hours, the tide’s level will be roughly at the same stage again. The level of the tide may be slightly different, but tides repeat on a schedule of approximately 12 1/2 hours and 25 hours.

Following this schedule, a high tide that occurs at midnight would repeat itself at approximately 12:30 p.m. the next afternoon and again at 1:00 a.m. the next morning.

Between consecutive high tides, the tide will fall for approximately 6 hours and 15 minutes and rise again for 6 hours and 15 minutes. There are minor differences caused by the phases of the moon, and every day isn’t exactly the same, but the variation is rarely more than a few minutes. This general rule is close enough for a quick approximation.

I thought I had a pretty good grip on tides and had been using them for many years for surfing and to get boats in and out of shallow areas, but several years ago while learning about kayaking and kayak fishing, Colin Eagles of Salt Marsh Kayak Company in Wrightsville Beach (1-866-65-KAYAK or Salt Marsh Kayaks, Kayak Rental and Instruction, Wilmington, NC) explained tides so simply his words hit me like a jolt. Eagles referred to “Rule of Twelve.”

He emphasized how important it was to plan coastal kayak trips to work with the tides for easier paddling. He said understanding the “Rule of Twelve” was a top priority for coastal kayakers.

This rules states that in a 6-hour tide change, which is standard in our area,

1/12 of the water moves in the first hour,

2/12 in the second hour, 3/12 in the third hour, 3/12 in the fourth hour, 2/12 in the fifth hour and

1/12 in the sixth hour.

There are a few minutes at each end of a tidal movement when the tide isn’t moving called “slack water” or “slack tide.”

Adding these periods to the 6-hour movement of tides in one direction and the 6-hour movement of tides in the other direction gives the approximate 12 1/2 hours between similar tides. By using a tide table and considering the “Rule of Twelve,” it’s possible to get a close estimate of the stage and intensity of any tide.

Three basic tidal areas exist at the N.C. coast.

At the Outer Banks, the normal tidal range varies about 2 to 3 feet. Small changes are about average and larger changes occur near the time of the full moon.

At the central and southern coasts, the tidal range is generally just more than 4 feet, but increases to more than 5 feet for full-moon tides. However, it often increases to more than 7 feet for fall and spring equinox tides.

While these may appear to be large tidal fluctuations, there are areas in South Carolina and Georgia that have average tides of approximately 10 feet. A full tide change at Cook Inlet, Anchorage, Alaska, is approximately 20 feet. At the Bay of Fundy, Nova Scotia, the average daily tidal change approaches 40 feet.

Tidal differences generally are greatest during the full and new moons.

Full moons generate the highest tides; new moon tides aren’t talked about as much as full moon tides. They usually are the lowest tides of the month and create large changes, but can be higher than normal.

Full-moon periods during the change of seasons during spring and fall equinoxes usually produce the most extreme range of tides of the year. They may exceed 7 feet at the southern N.C. coast.

But during periods when the tides are extreme, changes still occur during the same 6-hour time frame. The difference is that water flows at a faster rate and tide-generated currents are much stronger than usual.

Wind speed and direction can affect tides by speeding or slowing changes. They also may affect the height of the tide change by pushing more water into an area or holding it back.

This phenomena is most noticeable at the edges of our larger sounds where a strong wind pushes water from one side of the sound to the other. The area at the upwind side will have its water blown away, resulting in lower-than-expected tides, while at the downwind side, water will pile up against the banks and create higher-than-expected tides.

Tide changes don’t occur at the same times or rates at all locations. The difference is usually greatest between locations near inlets and several miles inland.

At Morehead City the high tide at the Harkers Island Bridge averages 2 hours, 23 minutes later than at the ocean at Atlantic Beach. The low tide averages 2 hours, 42 minutes later. These fluctuations are shown at the Tide Guide at the rear of this issue.

This is an extreme, and the times vary proportionately for those locations between these two areas.

From this you will see that once you know the time for High/Low the least amount of water movement is in the first and last hour of a tide change.

 

[Nemrod]

This link may help, go down page to marine links, should be able to find tide charts.

Marine Weather : Weather Underground

N

 

[captain]

Also remember tide predictions are for specific points (Datum)along the coast. If you are east or west or north or south of the prediction point you have to add or subtract a time correction to get the tides at your location.

 

[perdidochas]

This old mountain boy needs a little help with tide tables. I’m thinking if low tide is 6:46 AM . High tide is 12:59 PM . That during this time is when the tide would be coming in. That’s when to do the shore dives. Is that right?

Diving in a tidal inlet (if the above were the tide times), I'd plan to be ready to dive a little before noon, and plan to get out no later than 2 pm. Also, as with almost everything, the best advice is to ask locals if possible. They will know the idiosyncracies of their area. Most local dive shops will be able to tell you the best time to dive particular areas.

 

[Miller]

Thanks for all the replies. I was thinking about the West Palm Beach area. Sometime in October.

 

[cdiver2]

Thanks for all the replies. I was thinking about the West Palm Beach area. Sometime in October.

West Palm Beach, Florida Tides Marine Forecasts Maps Charts Weather Radar

 

[Charlie99]

If diving along the Ft Lauderdale - WPB shoreline, do the tides really have any signficant effect when you aren't right next to an inlet?