Learning to read tide tables is an important skill for those who have a livelihood or enjoy recreational activities that depend on the sea, such as fishermen, divers and surfers. Finding low tides (low tide) is also important for beach combing and tidal pools. Reading tide tables can be tricky, but with a little practice you can learn how to read and interpret such tables.
Step
Part 1 of 2: Reading the Tidal Table
Step 1. Find the tide table
You should use a table that is specifically related to the area you will be visiting, as nearby beaches, harbors and fishing locations can experience dramatic differences in ups and downs.
- Local newspapers usually print tide tables near the weather information.
- The marina will most likely have tide tables that are specific to the area.
- Reference stations consistently collect data to provide detailed tidal information. Their findings are accessible online and can be found by performing a simple search.
Step 2. Look for the relevant date
Tidal information over a period of a week or more may be published in advance. If you plan to travel tomorrow, use tomorrow's date. If you have a flexible plan, we recommend that you look for the data that is most important to you, such as looking for low tides at the right time. This means you may have to wait a few days for the best odds.
Keep in mind that the timing of the highs and lows varies from day to day, so don't make plans for the next few days using today's charts
Step 3. Understand the Datum Chart
This term refers to the reference plane that is the benchmark for measuring tidal heights. This is the average low tide level. This number is set low so most lows will not go below this number. This figure is also a reference point used by navigational charts (nautical charts) to measure depth.
Step 4. Look for high tide information
High tides will be expressed as positive numbers, sometimes with a plus sign (+) in front of them. This figure shows how high above the Chart Datum the tide is likely to be at the highest swell.
- The high tide shown as an 8 tells us that at the highest level, the water will be 8 feet (2.4 meters) above the mean tide line.
- Note that outside the United States, such as in Indonesia, the metric system is used and measurements are made in meters, not feet.
Step 5. Look for low tide information
The low tide will be expressed as a small number, or possibly a negative number. This figure shows the relationship between the water depth at the lowest point and the Chart Datum. Because the Chart Datum is an average number, not an absolute possible low, sometimes the low tide will be below the average high tide line.
- If the low tide is stated as negative (-), it means that the tide will be below the Chart Datum. A -1 means the low tide will be 1 foot (30 cm) below the average high tide line.
- Low tides can also be expressed in positive numbers. The figure of 1.5 indicates that the low will be 1.5 feet (45 cm) above the Chart Datum.
- Note that outside the United States, such as in Indonesia, the unit of measurement used is the metric system.
Step 6. Read the install time
Depending on the location, high and low tides may occur twice a day or only once. Tide times may be listed in 24-hour units, also known as military time. Make sure you distinguish between the morning and evening tide times correctly.
- To read military time, remember that numbers continue after noon. So 1:00 might also be written as 13:00 because it means noon (12) plus one hour (13).
- If the number is large and you don't want to bother counting, simply subtract twelve to get the number in the a.m./p.m system. 23:00-12:00 means 11 p.m.
Step 7. Understand the direction of the swell
This information is often indicated by letters, which tell you which direction the wave is coming from. For example, the letter W means the waves will come from the west. This information is very important for surfers.
If the beach is facing north, but the waves are coming from the northwest, it means the waves will break differently when they hit the beach or break point (point break)
Step 8. Read the altitude and interval
Some tide tables contain predictions about wave heights, also known as swells, and wave intervals. The wave height is the distance between the crest of the wave and the trough, or the lowest point on the wave. The interval shows the average number of seconds that elapsed between waves when the waves hit the offshore buoy.
- For surfing purposes, longer intervals will create bigger waves.
- Shorter intervals will create gentler waves, which are safer for swimming.
- Large swells and long intervals are suitable for surfing.
Part 2 of 2: Understanding the Ties Link with You
Step 1. Learn tide patterns
Understanding local tide patterns can help you predict whether you will have two chances each day to go sailing or beachcombing, or just once. In general, tides take about six hours to completely recede and reach their lowest point, then another six hours to reenter until they reach their highest point.
- In many coastal areas, there are two high tides and low tides each day at almost the same height. Tides like this are called semidiurnal tides (double daily) and usually occur in the waters of the Malacca Strait to the Andaman Sea.
- In some places there are two highs and lows each day, but one tide reaches a dramatically higher height than the other, and such a pattern is known as a mixed tide. This pattern occurs in most of the waters of eastern Indonesia.
- In some places there is only one tidal cycle per lunar day (the length of time it takes the moon to make one complete rotation on its axis with respect to the sun), with one high and low tide in a 24-hour period. This pattern is common in the waters around the Karimata Strait, between Sumatra and Kalimantan.
Step 2. Take advantage of the tide
When the water reaches its highest level, the boat can safely pass obstacles that might cause problems at low tide, such as coral reefs or sand bars. This is often the best time to exit or enter the port.
- Use navigation maps to help you sail safely.
- If you want to travel by boat, either by kayak or by a large boat, you need to know the channel depth, which is not listed in the tide table.
Step 3. Explore the mid-tidal zone
Surfers often find the best waves when the water is between high and low tides, although this varies by location. At low tide the rocks may be exposed, or the seaweed may interfere with the boards. When the tide reaches its highest level, the waves may not break until they are too close to the shore to make it less suitable for surfing.
If you fish in an estuary, the larger fish will swim into the deeper water when the tide is out exposing a shallow area. This is a great time for estuary fishing
Step 4. Enjoy the low tide
During high tide, beach combers and tide pool enthusiasts have a great opportunity to see the marine life exposed. Rocky beaches such as those along the Washington and Oregon coast offer the best opportunities to spot marine life in the tide pools.
- Low tide may be more advantageous for tall ships that need to pass under bridges. Knowing the free space under the bridge and the height of the ship can help you choose the best time to sail in and out of port.
- Low tide exposes the mud and there you can dig for shells. You can start digging an hour or two before the expected low tide and continue your search an hour or two after the tide starts to re-enter. Look for small holes in the sand that squirt water when you step on the sand next to it.
Step 5. Consider the weather factor
The tides aren't the only thing to consider when fishing or frolicking near the ocean. Strong winds can change the predicted tidal depth by a meter or more. Storms can be dangerous for boats or shore visitors. Season also plays a role in determining what fish can be caught.
- If you're not familiar with the coastal area you're visiting, seek advice from locals on what to look out for.
- Pay attention to the weather forecast and be careful when exploring.
- Riptide (tidal water colliding with each other) can form on any beach with waves, for example the Great Lake and the Gulf of Mexico. Riptide is commonly found between piers or between sandbars. If you are caught in a current that is pulling you away from shore quickly, swim parallel to the shore to get out of the current.
