I thought I would go out sailing or rowing on the River Authie tomorrow, so I went online to check the time of High Water and found a useful Tide Clock for Fort Mahon that I could incorporate into the blog pages.You’ll find it on this page down near the bottom of the right-hand column.
The tidal range (the difference between high and low tide) can be 20 feet or so on this coast, which explains why there is so much dry sand on the beaches to fly kites, do sand-yachting or just play on at low tide. The tide here takes almost 7 hours to ebb, but only 5 hours to come back in, so it comes back in at quite a speed. As it passes over the sun-warmed sand the water is warmed up – making it nicely warm to paddle and play in.
When the tide clock hand is at the top, it’s high tide at Fort Mahon. When it’s at the bottom, it’s low-water. You can gauge the state of the tide, and whether it’s rising or falling by where the hand is when it’s between high and low-water. (It’s on French time, of course, which is one hour ahead of British time)
For me it’s important, because the boat can be launched easily on the river only when it’s about 2 hours either side of high water. Also, it’s hard work to sail or row downstream when the tide is flooding – or upstream when it’s ebbing.