Build the perfect sandcastle

What makes the perfect sandcastle? Is it the tallest one or the most intricate? The longest lasting or the best decorated?

How to build the perfect sandcastle - buckets and spades on the sand of Bournemouth Beach, near Bournemouth Pier

Photo: RNLI/Nathan Williams

At the RNLI, we agree with Professor Matthew Bennett of Bournemouth University: The best sandcastle is the one you have the most fun building.

But that doesn’t mean you can’t take pride in your creation.

Matthew is a professor of sedimentology, and he uses the science of sandcastles to get families excited about the grand scale of geological history. We hit the beach with Matthew’s tips, some RNLI lifeguards, and our buckets and spades, to see for ourselves how to get to the top turret of sandcastle achievement.

Step 1: Find the perfect beach

We went to Bournemouth Beach as it’s our local sunspot, it had lifeguards on patrol when we did our test in May, and its sand has been named third best in the UK (joint with Great Yarmouth and Tenby) for architectural feats. That’s according to a study of the UK’s 10 most popular beaches, carried out by Matthew and his team in 2005. Second place went to Bridlington. In at number one: Torquay.

Matthew says: ‘Torquay came out top for lots of reasons, but primarily it was because of the particularly fine sand composition, which gave the sand greater strength in load-bearing tests. It’s also very pretty, as it’s red because of the Permian/Triassic sandstone in it, so it also scored well in aesthetics.

‘Looking around the coast, you want a beach with quite a bit of shell fragments in it. You also want finer grains.’

The study was UK-only, so we took to Twitter to ask about Ireland. Bundoran was well regarded, while Portrush (part of the UK but not on the most-popular list) was also nominated as Ireland’s best sandcastle beach.

So you want to find a beach with fine-grained sand (sorry, Brighton). If it’s an unusual colour and there’s a spectacular view, that’s a bonus. And we recommend choosing a lifeguarded beach.

Step 2: Find the perfect moisture level

In Matthew’s tests, the ideal ratio came out as 1 part water to 8 parts sand.

But you might not have brought your measuring jug/chemistry set to the beach with you. The best part of the beach to find sand that’s pre-mixed with the right amount of water will be somewhere between the high tide line and the low tide line.

Step 3: Bring the perfect tools

There are different kinds of bucket, and many types of spade. Matthew recommends a simple, round bucket, ‘not the ones with the fancy turrets which when turned out produce a castle in itself’.

It can be difficult to unmould a castle from a fancier bucket, and you’re also losing some of the creativity and individuality that contribute to a truly great sandcastle.

When it comes to spades, Matthew adds: ‘There is a direct correlation between age, spade size, and the speed at which boredom sets in.’ Big kids (ie mums and dads) will get greater satisfaction moving proper loads with garden spades, while little hands will do fine with a nice bright plastic implement from the beach-side store.

Step 4: Lay the perfect foundation

Every fortification needs a solid base. Before you start building, make sure that the area of sand you’re building on is level, strong and firm. If you’re building on an area of dry sand above the high tide line, make a base layer of 8:1 wet sand and pack it down firmly.

Step 5: Adopt the perfect method

Opinions differ. The pros build upwards in layers, but that can be tricky. The easiest way for amateur architects to create a keep they can be proud of is to build a big pile of sand (with the correct moisture ratio) and carve it into submission.

Start at the top, so there’s less chance of you kicking away some beautiful basework while working on your battlements. If your project's particularly ambitious, you might want to consider bringing along a spray bottle full of water, so you can mist as you go if your surface sand starts drying out.

Don’t forget to bring plenty water for your party to drink as well. Construction is thirsty work.

Step 6: Tell the perfect story

Every good castle has a story. It could be Game of Thrones-style clan warfare or just playing at being lord of the manor. But don’t forget the real-life epic beneath your fingertips (and loitering grittily in your sandwiches): the story of the sand itself.

Torquay’s winning sands were part of a subtropical desert nearly 300 million years ago. If the sand on your beach looks a little red and rusty, it could well have once been part of a desert. Desert conditions lead to greater oxidation, and redder sand.

As the main attraction in a tourist town, the sand we’re building with on Bournemouth Beach is mainly imported from the Isle of Wight, so as well as the story of the dinosaur-vintage rock it’s made of, you’ve also got a very modern story of town planning and ingenuity.

Every beach, and every grain, has its own story. If you’re on Dog’s Bay Beach in Roundstone, Co. Galway, your sand will be pure white because it’s made mainly of shells rather than stone. Your castle is built from the remains of the vanquished.

Step 7: The perfect ornamentation

Pebbles, shells, driftwood and feathers … look around your beach for things to pimp your sandcastle. But if you add plastic flags or any other man-made architectural follies (like our Lifeguards flag), please remember to take them with you when you leave the beach.

Happy ever after

No matter how big your moat, nor how intricate your drawbridge, after a morning on the beach we all agreed that Professor Matthew Bennett is right. It is about the fun.

Matthew says: 'It’s the family involvement, the dads, the mums, the grandparents as well as the kids all getting involved to create something together. That’s what’s special. But it can also be used as a way to engage people in the science of geology.’