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Big warship (Georgios Kollidas/Getty Images/iStockphoto)
Big warship (Georgios Kollidas/Getty Images/iStockphoto)

COLLECTED WISDOM

Hitting a ship used to be a long shot Add to ...

Welcome aboard the brigantine Collected Wisdom, home to the most bloodthirsty band of cutthroats on the Spanish main. We were planning to attack a galleon or two today, but the sea is the teensiest bit choppy so we’re waiting for nicer weather.

The question

How did navy guns compensate for the bucking and rolling of the ship as they attempted to hit enemy targets prior to radar and automatic gyroscopic compensation? Peter B. Scully of Toronto wants to know.

The answer

“In the days of sailing ships, shots were fired at very close ranges,” write Dewi and Peter Williams of Kanata, Ont.

The idea was to have the opponents sail alongside each other and “blast away until one was so badly damaged that the captain would strike his colours – haul down the flag.”

Even so, many shots missed. At such short distances, they say, the rolling of the gunship would definitely have affected the range. “If a gun were fired at the top of an upswing of the gunship, then the shot might go right over the enemy. If fired at the bottom of the swing, the shot might plunge into the ocean.”

To compensate for this, says David H. Olivier of Brantford, Ont., experienced gunners would time their firing to the rise and fall of the ship.

In the days of sail, he writes, these naval battles were fought at ranges of about 550 metres or less. “As wooden sailing ships and cannons gave way to steam-powered, armoured warships equipped with artillery, these ranges increased. As a result, the science of gunnery came to rely on mathematics.”

Knowing the distance a shell would travel given a set amount of propellant (gunpowder, cordite etc.) and using increasingly sophisticated optical range finders, he writes, it was possible to use the elevation of the gun to (roughly) reach the target.

“The British and the Germans favoured different systems of ranging. The British would fire single shells until they achieved a ‘straddle’ – one shot slightly short and one slightly long – then zero in between those two results. The Germans used a ‘ladder’ system, whereby their guns would fire at preset increases in range until they determined the correct elevation.”

By the first decade of the 20th century, he writes, this was an extremely complicated procedure, and before the First World War some British warships were experimenting with primitive mechanical computers to determine ranges.

“Nevertheless, gunnery remained an inexact science. At the Battle of the Falkland Islands in December, 1914, two British battle cruisers were able to shell and sink their outgunned and outranged German opponents without any serious opposition. When the battle was over, it was determined that the British hit ratio was less than 2 per cent.”

Further notice

A final word in our discussion on how to find out how much propane is in your barbecue tank.

Keith Morrison of Vancouver says a full tank weighs around 18 kilograms. The weight of the empty container (tare weight) is stamped on the tank. The tare weight of Mr. Morrison’s tank is 7.7 kg. So, weigh your cylinder. Any weight above the tare weight will give you an indication of the propane remaining.

Help wanted

How did the Romans do mathematical calculations using Roman numerals? William Clark of North Vancouver wants to know.

Why are the bridges of cruise ships at the front and the bridges of tankers at the rear? asks Ed Cavin of Vancouver.

Follow us on Twitter: @GlobeDebate

 

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