by Gritter Griffin
“Interpreting and Using a Tide Table”
The first thing you need to know is that all tide tables for a given area use the average of the lowest of the low tides (the neap tides, remember) over a period of 19 years to determine a zero point. It is from this point that all the tidal rise and fall predictions are measured.
Another way to get this straight in your head is to go to your favorite shallow water fishing spot at the time of a low tide that is noted as “zero” on the tidal chart.
The depth of the water noted as “0” at the time of that low tide under ‘normal’ weather conditions (e.g. excluding any unusual conditions – heavy rain, strong wind, approaching hurricanes, etc) is what is known as the Mean Lower Low Water (MLLW). It is the average of nineteen years of tidal observations for the lowest low tide at “0” during each moon cycle.
Simply put, this is the depth of the water you can expect to find in that area at the lowest low tide when the chart reads “0”. If it is navigable at that time by pole or trolling motor, it will certainly be navigable during nearly any other phase of the tide when the water will be higher than it is now.
This is useful information because now you know that under reasonably normal conditions, if the tidal reading is “0” or above, you can navigate (i.e. fish) in this area of the water.
The exception to this “rule” is when the chart reads as a negative number (for example - 0.8). In this case the water level at that same spot will be 0.8 feet (0.8 ft x 12 in = 9.6 inches) lower than when it was at zero reading. If the area you have targeted is 2 feet deep at a zero reading on the chart, it will be 2 feet minus 9.6 inches (or 16.4 inches) at a -0.8 reading. So it can be helpful to know what the “zero reading” or MLLW is at a particular location.
Tide tables are presented in various forms and some of them appear to be very complex and undecipherable. The important thing to remember is that you are only looking for three specific pieces of information:
Tide tables are listed by name for specific areas of the water. These areas are usually well known and easily recognized areas that are heavily navigated. Each one of these areas has a named tidal station that continuously monitors the rise and fall of the water at that location. Locate the station closest to the area you will be fishing and use the data from that chart.
A graph is produced by these stations and records are kept of the data. It is this data that is used to make tidal predictions for a specific area. The historical highs and lows over nineteen years are averaged to produce the numbers you will find on a tide table.
This is a typical graph from the NOAA site and includes the month of January, 2007. The tidal station is the Empire Jetty at Empire, Louisiana.
Note the first highlighted line. Reading from left to right you can easily see that January 9th is a Tuesday, that the time of day is 07:34 LST (Local Standard Time), that the tide height will be 0.0 and that this is the L (low tide) for the day.
So, in this example if you were fishing an area somewhere in the vicinity of the Empire Jetty station with a reasonably flat bottom and you noted the water in your location to be 12 inches deep on January 9th at 07:34 AM (the “zero” point) you can easily calculate the water depth at any other day and time of the year.
The high tide for that same day occurs at 5:39 PM at is expected to be 0.2 feet (0.2 x 12 in = 2.4 inches) higher than the low. So the water in this exact same area at 5:39 PM will now be 14.4 inches deep.
Now let’s go on to January 17th. Note that the predicted low occurs at 5:12 AM and is noted to be -1.0. If you were to go back to the same area at this time the same water that was previously 12 inches deep on January 9th would now be wet mud. This is because the tide is now -1.0, or 1 foot lower, than the depth noted at the zero reading and there is no water there.
Conversely, if you return to this same spot on January 17th at 7:22 PM, the water will be 1.2 feet higher than it was the zero reading. Now you would find that the water which we previously noted to be 12 inches at a zero reading is now 14.4 inches (1.2 x 12 = 14.4 inches) higher and will now be 26.4 inches deep.
You can use the same method to calculate the depth of the water at any time of the month throughout the year. This is pretty helpful information especially when fishing areas of shallow water. You will know when you need to be out of an area in which the water may drop too low for navigation. You will also know before you even go out on the water if you will be able to fish in a certain area.
This tidal information is also very useful because the amount of water and the speed that it moves through an area can have a significant impact on fish and their feeding patterns.
When there is not very much difference in the height of the high and low tides for the day this tells you that there will not be very much water movement. In other words, the tidal movement will be slow without a very noticeable current.
On the other hand, when there is a significant height difference between the high tide and low tide, the amount of water that moves into and out of the same area will be tremendously increased. It is this increase in the amount of water that must move through the same area in the same amount of time that results in significantly increased velocity of flow, therefore tidal currents which spells “dinner” for fish.
A notebook is one of the most important items in your tackle box because, over time, it will make you a more successful angler than you would ever believe. Your observations of fish feeding behavior during these periods of time when there is almost no tidal flow versus other periods of time when there is a significant change in tidal currents (along with weather, time of year, etc) will be one of the most important aspects of your angling arsenal.
When you can target the time, the location, and the tide that the fish in a certain area are most likely to feed, you will have exponentially increased your chances of success.
We have all had one of those days on the water when we pulled up to a spot and just slayed ‘em. Every cast produced a keeper. The excitement and adrenalin from that experience stays with you forever. These are the stories and experiences that we relive and tell over and over around the ramps and at the dinner table. But how many times were you able to reproduce that day in the same area? How many of your fishing buddies were able to?
The notebook and the tidal information will allow you to do it over and over again.
Fish because you can!