Here’s an unstoppable scientific way to build the perfect sand castle-the night edition of West France

Matthew Robert Bennett, Professor of Environmental Geography, Bournemouth University

On the beach, some sunbathe and some read, but quite a few vacationers embark on the construction of a sand castle. But how do you make the castle solid and majestic at the same time? Fortunately, there are scientific formulas that may help you. Explanation with Matthew Robert Bennett, a professor of environmental science and geography.

Unless you like reading and water sports, building a sand castle is an essential part of your sea vacation, but how do you make it solid and majestic at the same time? Fortunately, there are scientific formulas that may help you.

It all started in 2004 when the tour operator asked my team to investigate the problem. As a sedimentary scholar, an expert on rock deposits left by water, wind and glaciers, I started by thinking about the most suitable beach type to build a sand castle. We compared the sands of the 10 most popular beaches (at that time) in the UK. You can build a castle on any beach, but Torquay beat my ranking with its stunning red sand, followed by Bridlington, followed by Bournemouth, Great Yarmouth and Tenby. At the bottom of the ranking was Lil Beach.

But even after the beach is selected, you still need to find the ideal place. This question is a function of personal preference. Some people prefer to settle not far from the parking lot so that they can clean up in the event of a shower, while others prefer to be near a cafe. Yet others opt for isolated locations, perhaps better protected from the wind by natural capes.

Torquay Harbor. (Photo: averoxus / wikipedia, CC BY-SA)

If you want to build a real fortress, you should erect the building upright. And for that, you need hard sand! The hardness of sand depends on two factors: the properties of the particles that make up the sand and the water that binds the sand together. The larger the angle of the particles, the better they fit. However, the more sand grains are carried by the element, the smoother it becomes. This is why fine shell debris is a wise choice for building a castle. Finally, the finer the grain, the better it retains moisture. And the water issue is very important in the immediate issue!

If the sand contains too much water, the castle will drip, and if it is too little, it will crumble. Therefore, you have to find the right ratio so that your castle stands straight and for a long time. Everything is a function of the surface tension of water, the “water meniscus”, and this phenomenon of placing a glass of water on a damp, smooth support can appear stiff.

Magic formula

Our experience has shown that for every eight buckets of dry sand you need one bucket of water to make a perfect sand castle. Or, if desired, there is the following magical formula: water = 0.125x sand. But don’t panic if you don’t have scientific equipment. All you have to do is find the location of the sand strip between the high and low tide lines, which is easily found by mountains of seaweed and marine debris. However, keep in mind that this area moves during the day depending on the ebb and flow of the tide.

High tide line. (Photo:

The following tips are about the quality of the tool. In my experience, there is a direct correlation between the age of the builder, the size of the shovel, and how early the boredom begins. Adults are very frustrated with mini shovels, and children want to use larger shovels, but they struggle. Plan different tools to keep your team atmosphere in harmony. The size and shape of the bucket is also important. I prefer simple, round buckets to castle-shaped buckets with spire. A round bucket will allow you to create lots of turns and details to achieve your dream monument by exercising your imagination.

And when building, think about the fictional story of the castle and its outdated fairy-tale cohort, as well as the actual story of the sand you’re dealing with. Each grain is certainly a fragment of rock, encapsulating disappearing mountains, ancient rivers, swamps, dinosaur-infested seas, climate, and a long history of past events. All elements tell the story of our planet.

Finally, a word about the size of the castle. Sure, you can walk through a discreet castle with clean towers, ramparts and moats, but the ones that make the difference on the beach and are the most successful are also the most impressive. Think big! Pebbles, shells, driftwood and feathers can decorate your work. And to be honest, the sand castle is made to be admired. And there’s a bit of science behind the perfect castle, but most importantly, enjoy building it.

The original version of this article was published in conversation..