The miracle of tides by Mark and Hugh
This week's combination of Mark and Hugh's witty words and clever cartoon for the education, provocation and amusement of our New Forest readers
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Tides, perhaps the final mystery
It was a royal who once thought he had power to stop the tide; probably at a place not far from Canute Road in Southampton. Surely no modern-day jet-setting royal would ever display such arrogance? Time and tide wait for no man or woman, these forces are as inevitable as death and taxes. For the moment if we can put any thoughts of a certain Mr G Reaper and Mr R Sunak to one side, perhaps we can dream of the force that holds our worlds together in this vast darkness.
Have you ever wished that someone could explain to you exactly what gravity is? We all know what it does. At one time or another you must have dropped a champagne flute onto the kitchen floor. How many times have we picked up a fallen toddler? Also, no matter how many times our childhood dreams told us we could, we cannot fly. Gravity works all right, but how? We are marooned on this spinning globe in a seemingly endless black vacuum. Our moon is tied to us by the same invisible force that ties us to the sun. The whole thing is a delicious mystery.
Do you remember the fascinating experiment that was carried out on the moon? An astronaut called David Scott of the Apollo 15 mission dropped a feather and a hammer simultaneously. They both landed on the surface of the moon at the same time. Obviously, this was because there is no lunar atmosphere to slow the feather down as would happen on earth. This graphic illustration of physics must have inspired millions of schoolchildren to study harder, well apart from this slacker.
If you want a graphic illustration of the power of gravity take a walk down to Hurst Spit when there is a spring tide. Look on the internet or buy some tables, just look for the highest high and the lowest low. The sheer volume of water that passes through Hurst Narrows twice a day is astonishing. Some might say that it’s puzzling that we don’t harness this power. I have often heard scientists describe gravity as a weak force yet it shifts huge quantities of water around our globe day after day. How much fuel is required? Zero. This massive operation is routinely completed without burning so much as a single drop of oil, one nugget of coal or a solitary stick of wood. As you stand there on Hurst spit you might struggle with the fact that, day after day, we allow this precious resource to go to waste. We are told by educated people that there is no such thing as perpetual motion yet if you and I were to pop down to the spit tomorrow and the day after, the moon’s gravity would continue to shift the same enormous quantity of water. If this isn’t perpetual motion then what is? Wind power is an amazing resource that we are harvesting at ever reduced costs. Solar power too is becoming cheaper. But these natural energy sources are weather dependent whereas the tides, like a camera-struck politician at a Covid briefing, just go on and on.
Double high, the mariner’s dream
The Solent has a double high water and this is due to the Isle of Wight; the incoming tide which runs west to east fills the western Solent through Hurst narrows. Then as the tide curls around Bembridge there is a further surge as the eastern Solent is filled. A bar room expert once told me that this effect was due to the fact that we were situated at the middle of the English Channel. Apparently the see-saw effect gives us the double tide. Isn’t it amazing what knowledge three beers can gift a man who, thirty minutes earlier, walked into the bar as a sober idiot and in a short time will leave as a drunken one.
All you need to do is look at the tide tables for a port opposite us in France and you will see that they do not enjoy a double tide. In fact, I was chatting to the chap in charge of Chichester marina. He said that one day he laid on a pontoon and watched carefully as the tide rose on a nearby reed. He recalled that there was no pause whatsoever; once the tide had reached the highest point it immediately began to fall. Once again, we witness the power of gravity but we fail to explain the enduring and apparently fuel free nature of this force. Can someone explain this in simple terms? Not so much Southampton University, Early Learning Centre thank you.
Time and tide wait for no woman
The tides are created primarily by our moon which has a gravitational force one sixth of that of the earth. The sun also has some effect and it is when the sun and the moon are working together that we experience spring tides. When the forces of the sun and moon work against one another we experience neap tides.
Imagine that it’s a sunny Sunday with very little wind, perfect picnic weather. Your valiant skipper has found a quiet secluded creek. It is high tide at midday and carefully he guides the boat into some reeds where you slide silently to a halt. So far, so blissful and as you nibble at your sandwiches and sip the cool wine you fall back in love with sailing. Finally, it makes sense why he comes home on wintry Sunday afternoons, hands covered with antifoul paint and dust in his hair. The sun, the wine and the shushing sound of the reeds as they sway in the breeze have a deliciously soporific effect; soon you’re nodding. A short while later you are rudely woken by his snoring; the bottle is empty, the greedy devil. Standing up in order to stretch stiff muscles a horrible vision becomes apparent; there is no water, just mud. Prodding him gently with your deck-shoe you mutter “Oi, Captain Ahab, wakey wakey.”
The next high tide will be at gone midnight. It will be a cold, dark and frightening voyage back to the marina and 0300 before you’re tucked up in bed. You remember that the Monday morning alarm is set for 0600. Once again, you fall out of love with sailing.
In our modern world we no longer have mysteries. Tide tables predict precisely the height and time of both high and low tides. Astonishingly clever mathematical calculations give us mastery over nature; provided we both read and understand the results that is. Unfortunately, nature has a few surprises up her sleeve. Anyone who has been fishing in an anchored boat on a windy day can attest to the power of the wind upon the water. If you drop a line into the briny and watch the weight carefully you will notice that initially it will follow the direction of the wind but then after a foot or so it will change direction and follow the tide. Another little trick that works against our oh so carefully calculated predictions is atmospheric pressure. This varies enormously across the world. Sailors continually observe the ‘glass’ or barometer as atmospheric pressure is a good indicator of winds to come. A steep fall in pressure is typically a harbinger of doom.
If again you could refer to the tide tables, please look at the ‘unusual conditions’ section at the back. Here the publication warns of what can happen if certain situations arise. Consider that you are in an area of low atmospheric pressure and, say, a few hundred miles away there is an area of high pressure. These contrasting pressures will have an effect on the height of the sea. The high pressure over yonder will press down upon the sea and the low pressure where you are will allow it to rise. Differences in predicted and actual tides can vary enormously. This might seem academic until you consider parking somewhere like Bosham for a pub lunch; here people lose their cars on a regular basis. Storm surges which are a combination of wind and pressure can raise high tides by up to three metres above the predicted height. The power of nature is an awesome thing and should be respected.
We should count our blessings
There are those who don’t have the New Forest and the Solent on their doorstep as we do. We are so fortunate and we should cherish them both; drink in the beauty of your neighbourhood.
Take a peep, watch gravity at work. It’s amazing.
More tales and cartoons for Lymington and the New Forest from Mark and Hugh
If you'd like to read previous articles on diverse subjects written by Mark and illustrated by Hugh's cartoons, just click here!