Why Do Spanish Ships Have Glass Bottoms?

Today is St Valentine's Day. A day to celebrate Britain's love for playing the game of naval conkers with our friends from Spain. For it was on St Valentine's day in the year 1797 that a small British fleet met a much larger force from Spain offshore from Cape St Vincent on the coast of Portugal. During the engagement, the Royal Navy deployed a very large number of its best cast iron conkers and convincingly defeated the Spaniards.

The Battle of Cape St Vincent was just a single action in what became a thoroughly comprehensive thumping of the Spanish by the Royal Navy. With British assistance, over the course of a couple of hundred years, the Spanish navy involuntarily redeployed a very large part of its fleet to its "submarine" division.

Spanish submarines of the 18th Century were not entirely dissimilar to its formerly magnificent fleet of surface galleons. The main distinguishing features being the absence of masts and the very large collection of wooden splinters on their decks. 18th Century Spanish submarines were also noted for the ease with which they descended to the sea bottom and their innate incapability of rising to the surface again.

But, nonetheless they were a magnificent sight to behold. Beautiful wood carvings and ornate deck accoutrements. Thus, when the Spanish government realized the need to replenish the fleet, it sought to recoup some small part of its investment in the old fleet with one design modification. Henceforth Spanish ships of the line would be built with glass bottoms - so that Spanish sailors could see the old Spanish fleet.

But, back to our story of the St Valentine's day action at Cape St Vincent. The Spanish fleet was shrouded in fog as the British fleet under Admiral Sir John Jervis on board HMS Victory approached. Lookouts on board the vanguard vessel reported back to the flagship on the strength of the enemy.

"There are eight sail of the line, Sir John"
"Very well sir"

As the fleet drew further into the fog another signal arrived:
"There are twenty sail of the line, Sir John"
"Hmmm, fetch my scarlet waistcoat, they shall not see English blood if I should fall. Sail on!"

Moments later,
"There are twenty seven sail of the line, Sir John"
"Oh, buggah; better fetch my brown trousers too."

On that memorable day a British fleet of 15 ships defeated a Spanish fleet of 27 ships. British losses included 73 dead compared to 1000 killed on the Spanish fleet. Admiral Sir John Jervis was handsomely rewarded in cash and honours. The Spanish admiral, Don Jose de Cordoba was disgraced and discharged from service. Another reason to celebrate St Valentine's Day perhaps - unless you are Spanish that is.