Sand Castles Coast

Look on any sandy beach on a sunny day, and you can guarantee

that there will be dozens of aspiring architects at work.

As with any other property

the key to its success is its location.

Many resorts would have you believe that their sand is the best for building sand castles.

So along our journey we've chosen three great holiday spots to put that to the test.

Here in Weymouth, then Lyme Regis and finally Torquay.

With the help of Professor Matthew Bennett of Bournemouth University,

we're going to put the sand from each resort through a series of experiments

to reveal which beach has the best chance of making the ultimate sand castle.

What's the most important thing to look for when you're looking for the perfect sand to make a sand castle?

OK, I think it's probably water, because the water, the right mix of sand and water,

is the thing that's gonna make it stand up or fall down.

So kind of stick the sand together.

Right, so it's this property of cohesion, is the posh word

for that stickiness of the water, because it binds the grains together.

Now by lots of experimentation we reckon that the best

ratio of water to sand is eight parts sand to one part water,

but if you're wanting to build sand castles on the beach

you need to know where to look.

-Do you think you can actually spot this consistency on the beach then?

-Yeah.

-So where shall we start?

-Try and make a sand castle here and see what happens.

This is feeling a lot more like your eight-to-one mix.

OK.

-That's fantastic.

-The key thing is the smoothness of the sides.

-It's lovely and smooth.

-Just right there.

Now we're off to Lyme Regis and Torquay in our quest to find

the perfect sand castle sand.

Lyme Regis Council put a lot of effort into researching different types of sand for their new beach.

They believe they've found the perfect complement to their sea front,

but is it any good for sand castles?

We take a little bit of French sand...

We'll examine the quality of the French sand grains

to see how it compares to the Weymouth sand we tested earlier.

The first thing that's obvious is that the Weymouth sand is much more homogenous.

-That's right.

-It's similar grains throughout, very fine.

I'll just compare it now with the French sand here at Lyme Regis.

It's got a range of sizes - quite angular.

This helps the French sand bind together a little bit more.

All the different shapes interlock.

But what do the people whose opinion really counts

think about the new-look Lyme Regis sand?

It's quite grainy, it's quite sharp.

-Any hot tips then for building sand castles?

-Pour water over it.

Add a bit to the base as well, makes it solid to stick the castles on.

-Right, so you've got to have solid foundations.

-Absolutely.

Torquay recently boasted that it had the best sand castle sand in Britain.

It's a claim we're going to put to the test in the final stage of our sand castle quest.

After putting Torquay's sand through the same experiments as Lyme Regis and Weymouth,

we have discovered that Torquay and Weymouth are

neck and neck in terms of grain size and the angle of internal friction,

but Lyme Regis is not far behind.

Now for the ultimate battle of strength.

We're using measured amounts of water to increase the weight on top of our sand castles.

Which one will crumble first?

SHE GASPS

Oh, there's definitely a crack there.

This is going to be the fourth kilo.

-Yes!

-Yes!

-I told you.

-Lyme Regis, look at that!

'The French and Lyme Regis have been knocked out already.

'With only my Torquay and Matthew's Weymouth sand castles left,

'it's down to a straight shootout between the two of us.'

Mmmm... Aaaaah! SHE LAUGHS

Let's see how many more Torquay can take.

-Wow!

-Seven kilos!

-Whay!

-Yes!

Eight kilos. Torquay is the out and out winner.

-It took eight kilos to flatten it.

-Eight kilos...

What a mess!