Thursday, October 21, 2010

Southern Live Oak: Density that was Destined for Greatness

"I'm George, George McFly. I'm your density. I mean...your destiny." When the shy high school student George McFly confused the word 'density' for 'destiny' while trying to woo his future wife in "Back to the Future," he may have been on to something.

Today marks the 213th anniversary of a day when density changed the destiny of the United States of America. On Oct. 21, 1797, the USS Constitution - one of America's first naval vessels - slipped into the waters of Boston Harbor.

The 44-gun frigate nicknamed "Old Ironsides" was a ship unlike any other in the world at the time. Back in the days when ships were built of wood, the Constitution was built from a special mix of woods which were layered to strengthen the hull. Two of the most essential of the woods used in construction were southern live oak and white oak, both woods with very high densities.

Southern live oak was a secret weapon of the U.S. Navy. The super-dense wood grows only in the southeastern U.S., making it exclusive to the founding fathers. By combining it with the highly-dense white oak, the ship's builders made the hull even more impenetrable from enemy fire.

To understand why these dense woods were so important and gave the U.S. Navy such an advantage, we have to consider density for a moment. Imagine you are baking chocolate chip cookies and the recipe calls for one cup of packed brown sugar. First, you pour brown sugar into a measuring cup until it reaches the one cup mark. If you stick your finger in the sugar, it will sink in. Since the recipe calls for a cup of packed sugar, you force the sugar down and add more until you have a cup of closely packed sugar.
Now if you stick your finger in the sugar, it will be much harder to penetrate the top layer. You've just done a density experiment!

By forcing more sugar into the same volume - one cup - you've increased the density of the brown sugar. Density is defined as the mass of an object (brown sugar) divided by a certain volume (one cup) . As the mass increases for the same volume - as we pack more sugar into the same one cup - the density increases. And just as our denser packed brown sugar was harder to penetrate than the loose sugar, denser wood is harder for cannonballs to penetrate than less dense wood.

This density came in to play when the U.S. entered the War of 1812 against Great Britain. On Aug. 19, 1812, the Constitution engaged in its most famous battle against the British ship Guerriere. The two warships met at sea and opened fire at close range. Thanks to the special dense wood of the Constitution's hull, the cannon fire from the Guerriere bounced off the Constitution, falling harmlessly into the sea.

The sight of the cannon fire failing to penetrate the Constitution's hull reportedly incited one sailor to shout, "Huzzah! Her sides are made of iron!" giving the ship it's famous nickname. The Constitution then destroyed the Guerriere's masts, disabling the ship and winning the battle. Though this was a small battle at the start of the war, it was a propaganda victory for the young U.S.

Today, the Constitution, now the U.S. Navy's oldest commissioned vessel, is tasked as a floating museum. Visitors to Boston Harbor, where the Constitution is docked, can step on board to see for themselves the dense oak that changed the destiny of a young nation.

1 comment:

  1. Not only is Southern Live Oak "Dense" , It has other characteristics, that other dense woods do not, such as interlocked grain. This contributes to shock resistance (Cannon Balls,Splitting AX ETC). Steve Cross