Friday, August 27, 2010

predicting the next tide.

We can look at the beach and see where the water is, and even sometimes where it is going, but for us to camp on a beach we need some solid information. The tide line is for ever moving up and down the beach, and we need to be able to decipher what we see to figure out where our kayaks and ourselves can sleep. We need to determine where the last high tide was, and how high above that the next high tide is. If you look at the photo that I borrowed from a skilled photographer on the web you can see two distinct lines running across that beach from left to right. The line closest to the camera - running diagonally across the frame - this is the high tide. The line slightly further away that is less distinct is the low tide.

The more pronounced line is the last high tide, the one below it is the most recent tide, which was a low tide. This tells us that the next tide coming is a high tide again, and our tide table which we learned to read earlier in the week will tell us if the high tide that is coming is higher or lower than the last one. This is the information we need. The height of the next tide in relation to the last high tide whose remains we can see on the beach.

Just for clarity, I know that the low tide in the picture is newer than the high tide in the picture, because when the high tide comes in it will wash out the remains of the low tide. Therefore it must be newer.

So we can see the last high tide. if we pretend that the height of that tide is 8 feet (above mean low tide) and the next high tide is 6 feet. Then all we have to do is camp above the current high tide line. But if the next high tide is the 'high high' and its height is 9 feet then we need to do some figuring.

So for this example our next high tide is going to be one vertical foot higher than our last, lets go stand on that last high tide line and figure out the next high tide. To do this we are going to need our paddle, a half filled bottle of water, and the ability to accurately judge height or a tape measure.

Put your paddle blade on the tide line with the shaft perfectly vertical. Estimate the distance above the tide line that the next tide will be vertically up the paddle shaft, in this case, one foot. Hold the water bottle at the one foot line, horizontally, so it is pointing at the beach. Use the water in the bottle as a level to make sure the bottle is horizontal to the ground. Then sight over the top of the bottle to the beach, and mark that height - the spot you are looking at over the top of the bottle - I like to use a small piece of drift wood sticking up out of the sand. This is your next high tide line, and your tents and kayaks must be above it.

This is also a good time to touch the two tide lines and see how wet they are. The newer low tide should be wet to the touch, while the high tide should be a bit drier as it has been there longer. Get a feeling for how long it takes for sea grasses to dry in the sun, and you will have an easier time determining what you are looking at.

In the picture there is also scattered sea grass above the high tide line, this could be one of two things. As the month goes on, the tides will move in a cycle getting higher each day, until they reach an apex, and then slowly receding each day, until they reach the lowest point in the cycle and then they start over. This could be an older high tide, with the new high tides receding lower and lower. If your paddling when the cycle is receding, all you have to do is find the last high and camp above it, because the next high high is guaranteed to be lower.

Unless this scattered line is something else. A storm tide. When you get a Storm, High winds can drive waves higher on the beach above the high tide leaving a scattered layer of sea grass. Looking at this photo I would bet this is the case.

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