Reading Tide Charts

EVERY BEACH on the planet has a unique cycle of tides, and thus its own tide chart. Look for one in the local newspaper, or at a nearby marine store or surf shop.

Reading tide charts helps you pick the best times to go fishing, crabbing, or surfing. With boats, it helps to know what the water is doing, as paddling a canoe into a creek when the tide is trending low is a great deal harder than, say, swooping in with the rush of a coming high tide.

Tide charts come in different forms. Once you know the basics of high and low tide, water height, and moon phases, you’ll be able to read any tide chart.

FISHING: A NEW YORK TIDE CHART

This simple tide chart from Southold, New York, a fishing area, predicts tides for the first nine days of August 2006.

August 2006
Day	A.M.	P.M.
1		4:25	5:02
2		5:19	5:51
3		6:17	6:43
4		7:17	7:36
5		8:15	8:28
6		9:08	9:20
7		9:59	10:11
8		10:47	11:01
9		11:35	11:52

Plum Gut: minus 1 hour, 5 minutes.

Shinnecock Canal: plus 50 minutes.

Sag Harbor: minus 40 minutes.

• new moon

first-quarter moon (waxing moon)

full moon

three-quarter moon (waning moon)

This is a high tide chart because it’s primarily for fishing. When you fish, you wake up in the morning and before even opening your eyes you wonder, “When’s high tide?” High tide is when the fish are out and moving, whether on the incoming flood tide or the outgoing ebb tide. At least that’s what you hope. A smallprint note at the bottom of this chart mentions that low tide comes about six hours later.

The names and times beneath the chart explain how to calculate the tides for nearby beaches, since every bay and inlet will have slightly different tides.

Notice several things. First, high tide comes 50-60 minutes later each day. The tidal day is slightly longer than our regular 24-hour day, at 24 hours and 50 minutes. (Why? Because our regular days rely on the earth rotating around the sun, and tidal days rely on the moon rotating around the earth, which takes 50 minutes longer.)

Second, the tide chart lists the phases of the moon. During the first few days of August the moon will wax to a first-quarter crescent. The moon will be full by August 9th—and with any luck it will be a bulgingly orange late-summer moon, rising low and pumpkin-like in the sky.

Tide charts show the moon phases because tides are caused by the pull of the moon’s gravity—and the sun’s gravity—on earth’s water. It’s an awe-inspiring concept that the moon’s pull—even at 239,000 miles away—is so strong that it can control our ocean waters. Next time you are at the seashore, with the waves lapping at your feet, you can observe the power of the moon.

More practically, tide charts list moon phases because it matters when you go fishing. High tides are higher during the new moon and the full moon. These are called spring tides. People who fish don’t much like spring tides—the water level is higher, and silt and sand from the bottom churn up and make the water murky. The result: Fish can’t see the bait on your line, and that’s no good if you’re trying to catch them. Some people will plan their fishing trips way in advance using the moon phases of tide charts, knowing to avoid the few days around new and full moon.

The opposite of high water spring tides are neap tides. They happen during the first and third quarters, when the moon waxes and wanes. There’s less water at high tide, and slightly less current.

There are two more moon trivia words you’ll want to know: a crescent moon is anything less than half, and any phase slightly-more-thanhalf to just-under-whole is a gibbous moon.

CRABBING: A CAPE COD TIDE CHART

The next chart shows low tide, which makes it helpful for crabbing and beachcombing. The initial Time column lists the first tide after midnight, no matter whether it’s low or high. Set your alarm clock, because that first tide comes in at 5:18 in the morning. The next column, Height, tells that the height of the water is 0.0, or average water level, and that the tide is L, or low. If you’re not an early riser, look for the second low tide of the day. Reading from left to right, you’ll see a high tide at 11:10 A.M., and then another low tide at 5:09 P.M. That’s the one you want.

At 4:00, then, head for the beach. The hours just before and after low tide are especially good for beachcombing and crabbing. Low tide is also a good time to see birds along the shore. They’ll be there picking at small animals and crabs that were left on the beach after the water receded.

SURFING: A COSTA RICAN TIDE CHART

This chart from Nosara, on the Pacific coast of Costa Rica shows the tides in 24-hour time, which is used throughout the world, especially in non-English-speaking nations. (In the United States, 24-hour time is called Military Time, since that’s where it’s most often used.)

Hours 13-24 are equivalent to 1 P.M.-12 A.M. on the 12-hour clock, so to convert, just subtract 12. Thus high tide at 16:13 is 4:13 P.M., and low tide at 22:21 is 10:21 P.M.

Globe-trotting surfers, even American ones, must get used to 24-hour time so they can easily read the tide charts as they travel across continents, surfboard under arm, seeking the perfect wave. This chart does a great job of showing how high the waves will swell. For surfing, the combination of tide, wind, and swell determine whether any given surf spot, or break, will have rideable waves at any given hour.

For example, a reef break means the waves are created (or break) when incoming water hits a reef that comes up from the ocean floor. At low tide, a reef break may give an excellent ride, on fast, steep waves. At high tide, however, the water may be so deep that it does not make strong impact with the reef, and this results in barely any wave to ride at all.

On the other hand, a beach break means waves form off large sandbars underwater. Often a higher tide is best for these surf spots, because they need the force of a lot of water rushing over the sandbars to make long, rounded waves.

BOATING: A CALIFORNIA TIDE CHART

By now you’re an old hand at reading charts. The last chart comes from Half Moon Bay, California. It includes longitude (37.5017° N) and latitude (122.4866° W), which you’ll want to know if you’re taking a boat out on the Pacific Ocean and using your navigation equipment to find your way back to shore.

The chart also gives times for sunrise and sunset, so you can get out on the water early and you’ll know when you’d best return to the marina before nightfall. Notice, too, how the date is notated, as year-month-day; that’s standard tide-chart notation.