I’ve been on Anglesey all week, mainly to take a short break from it all. The Olympus was with me but photography wasn’t the priority; taking it easy as well as exploring was. Although I’ve been to Penmon Point and the lighthouse my wife never has so Monday we paid a little visit. As you can see not great weather but I was lucky to capture this little boat rounding the lighthouse on it’s way through the Menai Strait which separates the island of Anglesey from the mainland of Wales.
About 25 km (16 miles) long the shallow strait is influenced by the tides which cause very strong currents to flow in both directions through the strait at different times, creating dangerous conditions. The “Swellies” is considered to be the most dangerous area of the strait and this is located roughly between the two bridges that join Anglesey to mainland Wales. In this area rocks near the surface cause over-falls and local whirlpools, which can be of considerable danger in themselves and cause small boats to founder on the rocks.
The strait varies in width from 400 metres (1,300 feet) to 1,100 metres (3,600 feet), narrowing in the middle to about 500 metres (1,600 feet). Stand on the hills above the strait at the Swellies and you will see different current flows and whirlpools all moving fast roughly about 4.8 knots when the tide is flowing. The effect of the tide approaching from the south-west cause the water to flow north-eastwards as the levels rise. But that same tide flows right around Anglesey and several hours later it starts to flow into the strait from the opposite end. The tide continues to rise in height but the current flow is reversed through the strait.
For sailors who do not wish the long journey round Anglesey passage through the strait is the only answer. But there is danger if the passage is not done at the right time. As Sailing Almanac explains;
The flood enters the Menai Straits initially at the southern end at Caernarfon and quite some time before it enters through the north at Puffin Island – at times 6 hours out of phase and with a tidal difference of almost a metre. This means there’s a virtual moving waterfall as the water chases itself in and out of the Straits. It also means that HW and Slack Water do not coincide, however in order to traverse the Straits, especially through the Swellies, we need to know where this area of slack water is moving. Thanks to the magnificent studies made by the Oceanographic Dept of Bangor University we can plot the moving schedule of this slack water relative to HW Liverpool, as if like a bus time table. At various points along the Straits, we need to catch this movement of slack water in order to traverse the Straits, perhaps even with just a knot of tide in our favour. Any more, is a recipe for trouble.
And that to me seems like an Adventure. I hope you agree?
- The Isle of Anglesey (englishhistoryauthors.blogspot.com)
- This Day in the Yesteryear: Britannia Bridge Opens (1850) (euzicasa.wordpress.com)
- Pont Menai (morfadulas.com)