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A Deeper Look
The Functions and Accuracy of Tide Watches

The tides are ever changing and have been since the forming of earth's oceans and the celestial bodies that govern their actions. In fact, ancient cultures once believed the actions of earth's bodies of water to be the very wills of mystical sea gods themselves. Calm seas meant pacified and happy gods; and angry seas thus heralded angry and displeased gods. Learning to understand and read both high and low tide has been the mark of any truly great civilization. In fact, experts at understanding and navigating the seas were critical in the success of civilizations from the dawn of seafaring up into the modern era. Leif Ericson, Christopher Columbus, Ferdinand Magellan, and Jacques Cartier all made significant contributions to their countries of origin and to civilization as a whole based on their understanding of the seas. As such, their names are forever ingrained in the minds of their people and upon history itself. The advent of modern technology now allows you to become a master of the tides as well, with the unwavering direction of a special tide watch. Truly understand the mysteries of the seas and precisely predict the rise and fall of the tides.

The popularity of tide watches has created enough production of them to fill the Dead Sea a million-fold. But what goes into the accuracy of a tide watch? More importantly, what makes a tide watch for right for you? Well the short answer is the accuracy of your watch's tide graph.

What Is A Tide Graph?

A tide graph is the visual representation of the level of a tide based on the position of the moon and the sun at your location. The term tide graph can be applied to this type of visual representation for various purposes including the visual display on wristwatches. Watch manufacturers display this data in various ways, but you can expect to see a graphical representation similar to [Fig 1.1] on most digital tide watches.

[Fig 1.1] Watch manufacturers display tide graphs in different ways but all graphical variations essentially represent themselves in the same manner as that seen above.

If your watch has an inaccurate tide graph, then it is altogether useless when it comes to forecasting low and high tide. Even though your watch will likely have a plethora of other useful features, none are as essential to many maritime activities as a tide graph. Whether you are a fisherman, surfer, boater, deep sea diver or just someone who enjoys being on the water a good tide watch can make your activities safe and more fun. You just have to do some digging (or diving) to discover the right tide watch for you.

Before we dive into the subtleties of each watch and what makes them unique, you will need a basic understanding of the tides themselves and the reasons behind their volatility.

Tide Charts - Understanding the Basics

Tide charts are a historical record of water levels throughout a body of water at different points in time. There are a limited number of locations that tide charts are actually available for. Tide watch manufacturers rely on tide charts and their accuracy in their tide prediction functions.

What Causes Tides Anyway?

To understand what goes into a tide watch, we must first participate in a little science lesson. By definition a tide is the alternate rising and falling of the sea, usually twice each lunar day (more about this later) at a particular place, due to the attraction of the moon and the sun. Theoretically, the tides should rise and fall about every six hours; however factors such as friction, the topography of the sea floor surrounding the area, the shape of the shoreline, and prevailing weather patterns have a significant effect on the times of the tides. A tide graph will plot and show the tidal movement based on the Moon's movement over a meridian and the lunitidal interval that follows.
Meridian - a circle of constant longitude passing through a given place on the earth's surface and the terrestrial poles.

Lunitidal Interval - the average time difference between when the moon passes over a time meridian and the following high and low tide. If the time meridian referenced is the local time meridian, then the lunitidal intervals are called the "Local Intervals." The Greenwich meridian can also be used, in which case your lunitidal intervals would be noted simply as "Greenwich Intervals."

The Moon's Effect on Tides

Three main factors are in play and affect any given body of water when a tide is formed. The first is the effect of gravity between the moon and the earth. The second is the effect of gravity between the sun and the earth. And the third, the impact of the earth's gravitational force on itself. The moon has the most gravitational pull on the earth and therefore also has the most significant impact on the tides. In fact the moon's gravitational effect on the earth is over 2 times greater than the sun's because the moon is much closer to the earth than the sun.

For the purpose of understanding how the moon affects the creation of the tides, think of the earth as a perfect sphere surrounded by water. Wherever the moon happens to be, the water directly beneath it will be effectively pulled towards the moon. Where gravity pulls it must also push, so the water on the direct opposite side of the sphere is essentially pushed away from the moon. These forces cause two bulges of water to form. One bulge will form under the moon, where the attraction is the greatest, and one bulge will form on the opposite side, where the attraction of the moon's gravity is the least. These two bulges are known as the high tides, and the water that is displaced by them creates the low tides.

As the moon revolves around the earth, the two bulges will effectively follow it as the moon's force is applied to the area of water directly under it and opposite it. This is what causes two high tides and two low tides at various locations across the earth's surface. [Fig 1.2] These two tides occur twice each day, well almost twice each day…

[Fig 1.2] This graphic shows a visual representation of how the moon and sun create the tidal bulges.

Does High And Low Tide Occur At The Same Time Every Day?

One day on earth is measured as 24 hours. This is the amount of time it takes the earth to revolve around the sun. This is referred to as a solar day. Every 24 hours and 50 minutes the moon completely revolves around the earth. This is known as a lunar day. Due to the extra 50 minutes, our 24 hour clock is not measuring a lunar day. Therefore high tide and low tide generally will not occur at the same time each day nor would two high and low tides always occur over the span of one day as measured by our 24 hour (solar) clock.

How Does the Moon's Phase (or Lunar Phase) Affect the Tides?

We have covered why tides occur when they do, but the water's height differential during tidal fluctuation is equally important for safety when predicting tidal activity. The height differential in tidal fluctuation is referred to as tidal range. There are different titles assigned to the tidal range and frequency at which tides occur. You may have heard of spring tides or neap tides. These types of tides are created based on the lunar (moon) phase.

For example, spring tides occur just after a new or full moon. This is when the sun, moon and earth are for intents and purposes, aligned. Spring tides typically experience the greatest tidal range. Neap tides occur just after the first or third quarters moon so the tidal range fluctuates to a lesser degree. For that reason, most good tide watches also have a moon phase function.

So, What Features Do I Need In A Tide Watch?

Now that you have some background into the science behind tides, we can explain the accuracy and features on modern tide watches. No tide watch is more accurate than the other. There are different types of tide watches which relay the potential tide and tide range. The following information is a breakdown of the features that you might useful in a tide watch to suit your own personal lifestyle requirements.

Analog Tide Watches vs. Digital Tide Watches

This is a personal decision when it comes to deciding what type of tide watch is right for you. It is a misconception that analog tide watches are across the board inferior to modern digital tide watches. Watches you may consider if you prefer a watch with dials in lieu of a computerized display are the Rip Curl Eclipse Tidemaster, for its stainless steel body and water resistance, and Nixon Channel T for its easy-to-read moon phase display.

Real Time Pre-Programmed Tide Charts

Tide charts vary based on location and the amount of data that can be stored on a watch is limited. You should check to see what beaches have tide charts on the watch you are considering. The number of pre-programmed tide charts can vary greatly between brands and even different watches within those brands, so if you plan to use your watch to forecast tides abroad, the number of pre-programmed tide charts will be of interest to you.
Rip Curl
Most Rip Curl Watches (Tidemaster, Oceansearch, Oceantide Series) in Rip Curl's lineup have 200 preset locations, can track custom locations, and have the "Spot-X" function.

The Nixon Lodown has 145 preset locations and has the ability to keep track of custom locations as well. The Supertide covers 230 beaches and custom locations. Other watches throughout Nixon's lineup cover 200 beaches.

The 38mm Shark Classic, which will cost you around $90, and the 48mm Killer Shark, which costs around $95, both have sunrise/sunset data and tidal information for 150 preset beaches worldwide.

Casio watches do not make use of pre-stored tide charts but calculate your location information when you set up your watch. Older models require a user to input their latitude, longitude, and the lunitidal interval of their location in order to properly track tidal information, but some users found this process difficult, which prompted a change. In newer Casio models, one simply has to enter their home city in the tide function of the watch, and the time of the next high tide on the same day that you are setting the watch, and it will use this information to accurately track tidal information for you. Technically the functionality that Casio delivers is similar to the customizable tide charts the other brands provide.

Customizable Tide Charts

Since there is not a tide chart available for every location worldwide, many of higher end tide watches give you the ability to customize an existing tide chart for a local beach that is preset - allowing you to see a modified result for your next high or low tide times and tidal direction. Typically, the tidal range (high tide being at 8 ft. for example) won't be displayed because your watch has no way of modifying your pre-set location to give you an accurate tidal range for your new, custom location. Some also allow you to add completely new locations. This operation on the watch is typically performed by identifying the pre-stored beach closest to you and entering the time offset between the two locations. As long as the beach that you are using a custom setting for is still within the same meridian as the factory set location you have used to find your offset, tidal accuracy will still be maintained because your lunitidal interval still occurs at approximately the same time. In other words, if I have used the Ventura Beach factory set location to find a custom setting for Hollywood beach, provided I have entered the correct offset, the tidal information being displayed would still be accurate because the times at which the sun rises and sets and the times at which the moon rises and sets are roughly the same for the two locations because they are still within the same meridian. Other factors, however, such as the shape of the local shoreline and the topography of the seafloor will still have minute variances that cannot be accounted for.
Rip Curl
The preset tide charts stored in all of Rip Curl's tide watches can be customized to your particular location if you require tidal information for a beach that is not preset in your watch. This is done by using the closest preset location to the custom location that you are trying to set, and then finding the time offset between the two to start keeping accurate tidal information for your new custom location.

Rip Curl's Spot-X Function

Alternatively, if you are using a location that is not near a preset location already stored in the watch, you can still track tidal information for that location using Rip Curl's "Spot X" feature. This function allows you to enter a custom location and track its tide data. It is useful if your local beach isn't already on the preset list of beaches on your watch. This is done by simply finding the next high tide time for the location you wish to use, and then setting the month, date, and hour. Now, you can start keeping accurate tidal information for your new custom location. Spot X follows the world accepted average tide cycle of 6hrs 12mins and 25 seconds from high tide to low tide, so the tidal information for a custom location will always be an approximation of the real-time tidal information for that location. It will still be accurate enough to use for most recreational purposes however. No tidal range information will be displayed for the Spot X location because it cannot account for lunar information such as moon age or phase, only the time of the next tide and the tide direction graph. This information is readily available in your local newspaper or on-line, and it is relatively easy to figure this information out for yourself if you wanted to know roughly how high or low a spring or neap tide would be for example. On a side note: creating a custom location will overwrite the preset that you used to calculate the offset. If you need the pre-set location again, the information can be restored to a default setting, but of course your custom location will be lost. This information will be stored as Spot X (Alternatively, you can rename it to whatever you like) on the bottom of your tide chart and will not overwrite the pre-set location; it is simply stored under the Spot X (or whatever you have decided to call it) heading for that particular region.

The Nixon Lodown is able to track tidal information for a custom location. You must first find the closest preset location stored within the watch. Then, find the next high tide time at your custom location. Reference the closest preset location's high tide time, and find the difference between the two to find your offset time. Input this data into your watches tide function and it will now show the tidal information for your new location. This feature is useful for tracking tidal information for beaches that may not come in the factory preset list of 145 beaches for the Nixon Lodown.

Casio watches are unique in that they do not come with a list of pre-set locations stored within the watch. With a Casio, one just simply adds the data for a function known as the "home city" and the time of the next high tide, and the watch will start to track tidal information for that location.

Freestyle watches do not have the ability to edit locations within their lists or to set up custom locations, but do have durable and comfortable silicone wrist bands, night vision backlighting, and Dual Time displays.​

Difficulty In Setting The Tide Watch Functions
Rip Curl
There are 9 steps to set-up the initial tide function of your watch.

  1. Press MODE/SET to advance to TIDE MODE.​
  2. HOLD MODE/SET in for 2 seconds to enter beach setting.​
  3. To toggle between REGIONS use START/STOP & LAP/RESET.​
  4. When you find desired region press MODE/SET.​
  5. Use START/STOP & LAP/RESET to toggle through to your desired COUNTRY.​
  6. Press MODE/SET to lock in your country.​
  7. Use START/STOP & LAP/RESET to toggle to desired BEACH.​
  8. HOLD MODE/SET in for 2 seconds to save selected beach.​
  9. Once you set your beach you can use the START/STOP & LAP/RESET to toggle through all tide information for today as well as past and future tides. You need no additional info if you are using a pre-set beach, simply select the beach from the list, enter the correct button combination to start the set-up found in the user manual, set the date and time, and you are ready to go.​

Nixon offers a process similar to Rip Curl as long as you are using a pre-set beach. If you are using a custom location, the process is slightly longer but is relatively easy to follow. Detailed and pictured instructions are offered from the company. Click here to view them.

Has a slightly more involved 5-step process.

  1. Press S3 button to select TIDE mode. The corresponding number and name of your selected favourite tide location will be displayed.
  2. After approximately 2 seconds, any one of the thrree data display modes (DATA OF NEXT TIDE / SUNRISE TIME / SUNSET TIME, depends on the display mode left off during the last browsing) will be displayed.​
  3. To change from one data display mode to another, press S4 button once.​
  4. DATA OF NEXT TIDE: Current date Current tide level Upcoming tide levels Previous tide levels Time of the next tide Height of the next tide with high (H) / low (L) tide indicator.​
  5. In DATA OF NEXT TIDE mode, press S1 button or S2 button to display the data of the previous tide and the next tide respectively. The time of the next tide will come with the letter A/P representing A.M./P.M. in 12-hour format.​

Tide Chart Life

Tide chart life is the amount of time in years that a particular watch's tidal information will remain accurate for. There is a lot of variance in tide chart life from manufacturer to manufacturer and even from watch to watch within a specific brand. For that reason you will want to know the tide chart life of a particular tide watch before you buy it. If a watch with a pre-programmed tide chart is important to you and you plan on making a significant investment in this watch, you likely wouldn't want a watch with a tide chart life of less than ten years.
Rip Curl
All of Rip Curl's tide watches have pre-programmed tidal information that is accurate until 2099, and the future tide prediction system will predict any future tide until December of 2022.

Nixon's Tide Charts are accurate until 2020.

Casio watches do not make use of pre-programmed tide charts, and instead figure tidal information based on specific location of the wearer, in real-time. The accuracy of your watches tide graph should remain true for the life of the watch. If inaccuracies start to occur, simply re-enter your home city and it should restore accuracy.

The tide graphs on the Killer Shark and Shark are accurate until 2015, and newer models will be accurate to a later date that has yet to be released by Freestyle.

Future Tide Prediction

If you want to be able to plan traveling excursions based on tide data, you will want a watch that has a future tide prediction feature. Future Tide Prediction is simply the ability to see tidal information for a given location in advance of it actually happening. Because the information is being displayed in advance of it actually occurring and you have no way of visually confirming this in advance, it may be inaccurate. For example, if I wanted to plan a weekend fishing trip in Montauk, I could find out specific tidal information such as range and when a high or low tide might occur on Monday in advance of the trip, giving you plenty of time to plan when and where you need to be to fish at the best times.

Rip Curl
The Tidemaster and Oceansearch series will predict tides until December of 2022.

The Lodown only predicts future tides until 2016.

Freestyle Watches cannot predict future tides.

The Pro-Trek series of watches (as well as the G-shock) cannot predict future tide.

Moon Phase Function

If you want to know a tide's range you will need a watch that tracks moon phase.
Rip Curl
The Tidemaster and Oceansearch series' have moon phase functions. Lunar data is not available with the Spot-X function.

The Lodown and Supertide do not have any lunar capability, so spring and neap tides will be unaccounted for.

The Shark and Killer Shark do not have any lunar capability, so it will not be able to factor things such as a spring tide or neap tide when displaying tidal information.

Certain models within the Pro-Trek line do have lunar capabilities, such as the PRW2500T-7, but not all of them do. It is best to thoroughly look through the description of the watch that you are trying to buy to make certain that your watch has lunar capability. It will be listed clearly under the description about the tide graph for your particular model whether or not it has lunar capability. Most watches from the Pro-trek series will have lunar capability if they have tidal capability.

Display Tide Direction

All watches with a digital tide graph will display the direction and height of the tide, as the graph will have markers measuring in feet on the left side to measure how high or low a tide will be. These are the humps represented on a tide graph.

The Big Decision

Many factors can go into your tide watch purchase decision. Considering how many preset locations you will likely utilize, whether you would need customizable location settings, the longevity of your tide charts installed, whether you would need to view predictions of future tides, and if you would like to track the range of a tide are all functions which can set brands and models of tide watches apart. Which feature or set of features is most important to you? Is RipCurl's "Spot-X" feature more accurate for your custom location tracking or does Nixon's ability to set custom locations relative to its preset locations work better for you? The remoteness of the location you wish to track tides for may dictate which models will be useful for you. You may even decide that an analog watch fits your style because you appreciate the classics. Whatever your final decision may be, your purchase should feel as an extension of your own body and functionality. Hopefully this article helped you better understand the features and analyze what you actually need in a Tide Watch.

This article was written by the team at
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