I went off this morning to get my forth stabbing courtesy of the NHS. As a wrinkly I've had two vaccinations and now, two boosters. Later I went down to my boat where while pottering about on board, I heard an onlooker on the shore remark to her companion, " Doesn't the Tide come in slowly here." which set me thinking about Tony's recent post about passing on information, or knowledge if you prefer.
Now I'm not presuming to teach anyone to suck eggs, but the thought struck me that possibly forum members living inland or others with no real interest in the ways of the sea may benefit from a brief explanation about Tides that may help them avoid problems or even danger should they find themselves somewhere that Tides will effect them. I'm thinking of Bush Crafters who might be novice sea shore foragers, Beach Anglers or even just visitors to the Seaside.
Tides around our shores vary in their characteristics according to location, although the general rule is there are two high tides and two low tides every 24 hours...in most places..
The Solent on the South Coast and Poole have double high waters and Weymouth Bay for instance has a double low water.. but let's forget about the odd places and look at the general picture.
Going back to what the lady on the shore said, the incoming Tide ( The Flood) was indeed slow at the moment she commented, but the Tide was only in the first hour of flood and would accelerate, the water getting deeper faster as the Tide entered the 6 hour cycle to High Water.
To explain. In the first hour a Tide will make about 8% of it's total depth at High Water. In the second hour the speed of increase is about 17%, in the third hour 25%. So, 3 hours into the Tide (half Tide) the Tide reaches maximum speed of increase. The forth hour also runs at 25% and then the rate slackens, 17% and finally in the last hour before maximum High Water the Tide just makes the final 8% or so.
Once again, percentages are approximate and depend on area, but are a good general guide.
"Imagine someone filling a narrow neck bottle under a tap. Start slowly, making sure the water is going into the bottle, open the tap further as the bottle fills to half full, then slowly close the tap to a trickle as the water rises up the bottle neck to full."
And that's the way Tidal behaviour was explained to me at 16+ years of age when I joined my first ship..sorry about the quaint explanation..But at least I remember it nearly 62 years later..
Being serious though, many people have been caught out on the flat sands or Marshes and even rocky beaches difficult to escape from, because they didn't understand the Tides.
Far out on the sands of Morecombe Bay I bet someone has thought, "The Tide has been coming in for an hour but it's ok, it's only up to my ankles, there's plenty of time to get back to land"
In the next hour the depth of water doesn't just double, it's probably up to their knees and they can't wade as fast as the incoming Tide is deepening....In places like Moprecombe Bay and the Wash on the East Coast a Spring Tide will flood faster than a man can run/wade.
The actual figures for calculating Tides are not carved in stone, for instance there are 12 hours 20 odd minutes between the two high and low Tides each day and in some areas the Tide will 'Hang' and not start to flood or ebb exactly as predicted. Then there is local Barometric pressure to consider which can increase or decrease the depth of the Tide..then there's local wind direction..But if you are aware of the basic aspects of Tides then after consulting local Tide Tables AND listening to any local folk before you venture off foraging or Rock Pooling with the kids, you will be safer.
Now I'm not presuming to teach anyone to suck eggs, but the thought struck me that possibly forum members living inland or others with no real interest in the ways of the sea may benefit from a brief explanation about Tides that may help them avoid problems or even danger should they find themselves somewhere that Tides will effect them. I'm thinking of Bush Crafters who might be novice sea shore foragers, Beach Anglers or even just visitors to the Seaside.
Tides around our shores vary in their characteristics according to location, although the general rule is there are two high tides and two low tides every 24 hours...in most places..
The Solent on the South Coast and Poole have double high waters and Weymouth Bay for instance has a double low water.. but let's forget about the odd places and look at the general picture.
Going back to what the lady on the shore said, the incoming Tide ( The Flood) was indeed slow at the moment she commented, but the Tide was only in the first hour of flood and would accelerate, the water getting deeper faster as the Tide entered the 6 hour cycle to High Water.
To explain. In the first hour a Tide will make about 8% of it's total depth at High Water. In the second hour the speed of increase is about 17%, in the third hour 25%. So, 3 hours into the Tide (half Tide) the Tide reaches maximum speed of increase. The forth hour also runs at 25% and then the rate slackens, 17% and finally in the last hour before maximum High Water the Tide just makes the final 8% or so.
Once again, percentages are approximate and depend on area, but are a good general guide.
"Imagine someone filling a narrow neck bottle under a tap. Start slowly, making sure the water is going into the bottle, open the tap further as the bottle fills to half full, then slowly close the tap to a trickle as the water rises up the bottle neck to full."
And that's the way Tidal behaviour was explained to me at 16+ years of age when I joined my first ship..sorry about the quaint explanation..But at least I remember it nearly 62 years later..
Being serious though, many people have been caught out on the flat sands or Marshes and even rocky beaches difficult to escape from, because they didn't understand the Tides.
Far out on the sands of Morecombe Bay I bet someone has thought, "The Tide has been coming in for an hour but it's ok, it's only up to my ankles, there's plenty of time to get back to land"
In the next hour the depth of water doesn't just double, it's probably up to their knees and they can't wade as fast as the incoming Tide is deepening....In places like Moprecombe Bay and the Wash on the East Coast a Spring Tide will flood faster than a man can run/wade.
The actual figures for calculating Tides are not carved in stone, for instance there are 12 hours 20 odd minutes between the two high and low Tides each day and in some areas the Tide will 'Hang' and not start to flood or ebb exactly as predicted. Then there is local Barometric pressure to consider which can increase or decrease the depth of the Tide..then there's local wind direction..But if you are aware of the basic aspects of Tides then after consulting local Tide Tables AND listening to any local folk before you venture off foraging or Rock Pooling with the kids, you will be safer.
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