Understanding the Tides

It may be of no great surprise to learn that at Belhaven Bay the tide comes in and out during each day. There are however, seas in the world where this does not occur; next time you travel to the Mediterranean, have a long look at the shore and see what happens there. But if you want to know more about how the tides work and learn about  local tide times, read on…

The Tidal Regime

The biggest factor affecting the tide is our moon. The moon has a gravitational pull that affects most large waterbodies on the planet, causing the water to both rise and fall. This typically results in there being 2 High Waters, separated by 2 Low Waters over each 24 hour period – as a rough guide at least. So, if it is High Water at midnight (00.00hours), the tide then recedes to a Low Water mark by 06.00am, before rising again to the next High Water at midday, and then lastly receding for the second time to a Low Water at 18.00hours.

Things are complicated a bit by two further considerations. First, each day, the time for each peak and trough of High / Low water moves forward by some 45 minutes. So, using our example above, on Day 2 High Water would not be at midnight but 00.45hours, and so on. Secondly, during the moon’s 4 weekly cycle, it sometimes has a stronger effect on the water than at other occasions, producing what are misleadingly called ‘Spring Tides’. This is when the tide moves (relatively) further up the shore, and (at Low Tide), further down the shore. These phases relate to when the moon is either full, or when there is no moon (or, as it is correctly termed a ‘new moon’).

Guess what, in between these of lunar phases there are two periods – when the moon is only ½ full, when its pulling power is diminished. The consequence is the tides move only a small distance between their High and Low Water points – these are called ‘Neap Tides’. The final piece in the jigsaw to understanding the variations of the tide concerns the relative angle of the earth in relation to the sun. At two times each year – known as the Spring (about March 20th) and Autumn (About September 23rd) Equinoxes, the relative alignment of the earth to the sun (and the moon) exaggerates the strengths of the tide further still – and these are the two times in the year when typically the highest tides occur.

What About the Wind?

The description so far, whilst accurate, does not include one other important factor – the strength and direction of the wind. A storm-force wind, blowing onto the shore, can turn a Spring Tide into a devastating storm tide, reaching far above expected levels, and be extremely destructive. So always consider whether the wind is blowing onto, or away from the shore, along with how strong it is, when judging what the tide is likely to be like.

Tidal Information for Belhaven

Most newspapers have tidal information. Also, many websites provide up-to-date details, try www.bbc.co.uk/weather/coast/tides/Scotland and then select ‘Dunbar’ from the drop-down list of options. Or try www.easytide.ukho.gov.uk/easytide/EasyTide, again selecting Dunbar when prompted.

Why Should I Care?

Depending upon your interests, access to the wide sandy bay may or may not be an issue. If you get it right and arrive at Low Water, you’ll be met by a wide expanse of golden sand, for your delectation. If you get it wrong the area available for you to horse ride, kite-buggy, etc. will be severely impeded.

The Bridge at Shore Road at Low and High Water...

Can I Get Cut Off By the Tide?

If you are out on Belhaven Bay during one of those few times when High Water is particularly strong, you may find the salt-marsh that lies between the beach and Linkfield Car park (the big car park) becomes covered by water for an hour or so. This is increasingly a rare occurrence, however, so if you have the pleasure of experiencing it, either prepare for a wet wade, or enjoy your temporary desert island experience! Much more common is for people to mis-judge getting back across the metal bridge near the Shore Road car park. This gets cut-off by most high waters, so allow at least a couple of hours either side of High Water to use this bridge safely. If you do miss the bridge, you’ll have to walk back via Linkfield car park and then follow the bay round back to Shore Road.