May 18, 2014

The Maddison Project: Take 2


Medieval_.jpgMedieval illumination showing a mariner consulting a compass aboard a ship. It is the first known depiction of the use of compass on board a ship. The illustration is from a 1403 manuscript copy of Jehan de Mandeville (John Mandeville), Le livre des merveilles (originally published c.1355-57). The 1403 manuscript is held by the Bibliotheque national de France in Paris,



ANGUS MADDISON, the eminent economist, said there were three things that contributed significantly to improved sailing ships and increased trade in the 13th century. They came after about 1,000 years of scientific, economic, and political stagnation following the collapse of the Roman Empire.

The three significant improvements were:

1. The magnetic compass -- somewhat like the old windrose, but with a pointer directed continuously to the north.

2. The Venetian sandglass. This was designed to measure time accurately over a short time, and enabled the true speed of a vessel to be recorded.

3. The wooden traverse board, which made it possible to keep a reasonable dead reckoning account.

The traverse board  had a face with eight holes in each compass point, and eight pegs attached in the center. At each half-hour of a four-hour watch, a peg was placed in the hole indicating the course of the ship during that interval. In another part of the board, the average speed for that half-hour was recorded with a peg.

"About the same time, portolans (charts with an indication of ports, anchorages, tides, depths, and winds) began to appear," said Maddison. "They provided sailing instructions derived from the experience of earlier mariners. They showed coastal outlines and distances between ports, with an array of alternative courses (rhumb lines). If none of these lines was appropriate for the intended voyage, they nevertheless helped the mariner design and pursue his own trajectory, using a ruler and a pair of dividers. The portolans were made of vellum (a single sheepskin up to 5 feet long and half as wide) with directions inscribed in black and red ink.

"These changes increased the productivity of Venetian ships, which had previously not ventured the trip to Egypt between October and April, when the sky was frequently overcast. With these instruments, the ship could make two return voyages a year from Venice to Alexandria, instead of one."

According to Maddison, the 12th century saw innovations in shipbuilding technique that reduced costs and improved efficiency. In Roman times, he said, the hull had been constructed first. By this, I believe he meant the outer shell. "Ships were held together by a careful watertight cabinetwork of mortise and tenon. The second stage was the insertion of ribs and braces."

But from the 11th century onward, the keel and ribs were made first "and a hull of nailed planks was added, using fiber and pitch to make the hull watertight. Somewhat later, the stern-post rudder replaced trailing oars as a more effective means of steering. The power of rudders was strengthened by the use of cranks and pulleys, so it was much easier to maintain course in bad weather."

Another important change involved changes in the rigs of sailing vessels. In the Mediterranean, the Arab lateen sail became the rig of choice, instead of the age-old squaresail. Lateen sails made it possible to sail in a wider range of wind conditions, especially against the wind, and reduced the time spent idling in port or at anchor waiting for a fair wind.

In the 15th century the focus of maritime progress moved to Portugal, which was exploring the Atlantic islands and the coast of Africa. "There were big changes in rigging that permitted sails to harness wind energy with much greater efficiency than earlier Mediterranean vessels. With more masts and a much more complex array of sails, ships become more maneuverable and faster. They could tack into the wind with greater ease. The Venetian galley, whose motive power depended on oarsmen, become obsolete. A new type of vessel -- the caravel -- was more robust and able to operate successfully in the stormier seas and currents of the Atlantic." 

Today's Thought
There is no greater disloyalty to the great pioneers of human progress than to refuse to budge an inch from where they stood.
-- Dean W. R. Inge
A local junior-school teacher was trying to teach the concept of distance. She asked whether her pupils thought they lived close to school, or far away.

Nobody was willing to hazard a guess except little Susan, who was quite adamant that she lived very, very close to school.

“How are you certain?” asked the teacher.

“Well, every time I come home my mother says: ‘Hell, are you home already?’”

(Drop by every Monday, Wednesday, Friday for a new Mainly about Boats column.)

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