How to make the perfect sandcastle? Ditch the bucket and spade and use your hands
They're on sale at every self-respecting seaside shop but the bucket and spade - considered essential kit for a trip to the beach - are actually not as good as your own fair hands when it comes to constructing a sandcastle.
The perfect sandcastle: Researchers say the key is to use your hands rather than a bucket and spade
This is because neither is ideal for producing the highly compacted sand that is crucial for giving the structures strength.
The advice comes from scientists who carried out a number of experiments on how to construct the perfect sandcastle.
They began by looking at how much water is needed to produce a one that will not collapse from being too soggy or crumble from being too dry.
Physicist Peder Moller said: ‘We used some fancy instruments but effectively we put some sand in a cup and inserted a spoon and started to twist the sands a bit and measured how hard it was to twist.
‘We found that one bucket of water to 50 buckets of sand gave the highest strength.’
The team also found the optimum size for a sandcastle tower
At this ratio, the water forms strong bridges between the sand grains.
Their experiments, described in the journal Scientific Reports, show that the size of the sand grains to have little effect on the overall result.
However, compaction is very important, with sand that is well-packed up to 30 per cent stronger.
This is where the advice about buckets and spades comes in.
While it is easy to compress sand in a bucket, the structure becomes much looser on tipping out, said Dr Moller, of the Laboratoire de Physique Statistique de ENS in Paris.
And thumping the sand with a spade produces an uneven result.
Dr Moller said: ‘Buckets and spades can be great for larger constructions.
‘But compacting with a spade is not optimal since it tends to introduce fractures in the sand’s structure rather than compact it.
‘Ideally I would use spades and buckets to build a mound that has all the height of your dream castle while compacting (with hand) during piling.
‘Then finally carve away the residual sand that hides the magnificent castle inside.’
The scientists also calculated the maximum height for cylindrical sandcastles with bases of various sizes.
For instance, if the base has a diameter of 16inches, the sandcastle will topple if it is more than 8ft in height.
To build a sandcastle twice as high as one you’ve made already, you will need make the base roughly three times wider.