Size Matters

Dr Miodownik says that mathematical probability, rope type and bubble size all come into it. The bigger the bottle, the higher the mathematical probability of a natural defect, so he recommends using a jeroboam.

Forget about vintage, it's bubble size that counts. "The bigger the bubbles, the higher the pressure inside the bottle, the more likely it is to break on impact. The best option is probably to go for a cheap bottle of cava with big bubbles."

And increase this effect by giving the bottle a good shake.

A rope which has any elasticity in it will absorb the energy, so steer clear, says Dr Miodownik. Better than rope would be a length of wire.

While most ship bows are made of rigid steel, some parts will be even more solid than others - so x-ray the bow, locate the groins (main support structures) and take aim for these.

Then there is who - or what - will do the throwing. Ahead of Ventura's launch, a Royal Marine who specialises in ropework and mountaineering conducted a recce of the ship. Later this month, Royal Caribbean International will do away with the human element altogether when they launch their own large cruise liner.

Their godmother will press a button to activate a special machine to smash the champagne.

But this is by no means foolproof. When Jodie and Jemma Kidd helped launch Ocean Village Two a year ago, the automated mechanism failed to smash the bottle. A crew member on board had to step in and do the honours.