Digital Tide Clock Science

6/29/2016

How does a digital tide clock differ from a traditional mechanical tide clock?

  Let's start by talking about what a traditional, mechanical tide clock does well. They are pretty good at tracking tides on the Atlantic coast where they have predictable semi-diurnal tides - a high every 24 hours and 25.2 minutes. They do a pretty good job of telling you whether it is a high tide, low tide or somewhere in between. And I say 'pretty good', because they are mechanical devices prone to gradually losing accuracy over time and then must be reset. How often do they need to be reset? That dependends on the precision of their mechanism - which varies.  

Tides that mechanical clocks can track without manual adjustments:
 

  • Semidiurnal : two highs and two lows of similar height. 
    US / Canada Atlantic Coast

Now, let's look at these two tidal patterns below that are prevelant in other parts of North America. As you can see, they aren't predictable using the simple mechanized timer of traditional tide clocks.

 
 

  • Mixed Semidiurnal : two highs and two lows of dissimilar height
    US / Canada Pacific Coast.






     

  • Diurnal : one high and one low per day. 
    Gulf of Mexico

 
How do we tackle predicting these variations?

-- We go digital. --

So, how does a digital tide clock work?
 

    Tides are determined primarily by the moon's gravitational pull and secondarily by the sun's gravitational pull. Smart scientists have figured out where the tide will be at a particular location depending on its orientation to the sun and moon. And since we happen to know the position of the moon and sun accurately for the next few million years or so, we can also predict the tides for quite some time.  

    Now, the digital tide clock doesn't need to be smart enough to make these predictions. It only needs to be smart enough to memorize all these tide levels predicted by a much smarter computer program. This is achieved by storing all the variations of tides at numerous locations, so that given a particular location and date/time, the digi-clock can display the previous tide, next tide and current absolute tide height. With this kind of information, all tide patterns can be tracked - from simple to more complex.

   And because the digital tide clock uses a highly accurate oscillating crystal to keep time, it doesn't suffer from the gradual inaccuracy of mechanical clocks. In fact, it is accurate to within half a minute per year. 

  Given, this takes quite a bit of memory and processing power to pull off. But, recent advances in processors, storage and energy efficiency, allow a relatively inexpensive clock to be delivered to the market. 
 

  Please see our Digital Tide Clock for North America.