EUREKA Sep 19, 23:42
Apropos our heading to Trapani this week, it seems worth mentioning that Sicily was the birthplace, in about 287 B.C., of Archimedes. While few facts of his life are known, tradition has made at least two stories famous.
Archimedes
In one, he was asked by Hiero II, the Greek ruler of Sicily, to determine whether a crown was pure gold or was alloyed with silver. Archimedes was perplexed, until one day, observing the overflow of water in his bath, he suddenly realized that since gold is more dense (i.e., has more weight per volume) than silver, a given weight of gold represents a smaller volume than an equal weight of silver, and that a given weight of gold would therefore displace less water than an equal weight of silver. Delighted at his discovery, he ran home without his clothes, shouting “Eureka,” which means “I have found it.” He found that Hiero's crown displaced more water than an equal weight of gold, thus showing that the crown had been alloyed with silver (or another metal less dense than gold).
In the other story Archimedes is said to have told Hiero, in illustration of the principle of the lever, “Give me a place to stand, and I will move the world.” Even that ties in to the Cup -- reminding some of us of a few former AC designers who made similar promises at the outset of their campaigns, but, sadly, were able to leverage neither their standing nor their syndicate's ample resources.
No doubt the naval architects and other AC technical types can explain better than I the significance of Archimedes' discoveries about density and buoyancy -- and how they directly relate to the America's Cup. Suffice to say that two of the three main factors of the AC Class Rule-formula are directly related: a yacht's Displacement and it's waterline Length while floating in still water and in measurement trim. (The third factor is Sail Area.)
A yacht's Displacement will vary slightly but significantly with the density (ok, specific gravity) of the local water. Accordingly the Length will vary -- if the yacht sinks lower its waterline grows longer; floats higher, shorter. Hence the need for a correction factor when the measurers "float the boat" in waters of differing salinity, which, of course, affects the specific gravity of the water. Needless to say, the salinity of sea (and lake) water varies significantly from place to place around the world.
All that to say nothing of the technical teams being guided by Archimedes' principles in designing the yachts to fit within the Rule in the first place.
In Malmö our ACC Technical Director ("TD") might have been dubbed Ken "Newton" McAlpine. It was there that Ken and his measurement team used, for the first time in the history of the Cup, a gravity factor. Why?
Sir Isaac Newton
The earth is not a perfect sphere but a bit squashed at the poles and bulging at the beltline (seems age has a way of doing that to the best of us). Accordingly, the closer you are to the Poles the closer you are to the center of the earth; and the closer to the earth's dense core, the more gravitational attraction. So, nearer the Poles things weigh more than near the Equator (all other things being equal like your height above sea level and the local geophysics). [22 Sep update -- please also note the interesting comment by Frank Albina, below, about the centrifugal force factor.]
In a nutshell, when the yachts were re-weighed in Malmö it was soon realized that at least those which had not been changed in any way all weighed slightly more than they had in Valencia, hence the use of a scientifically-derived 50kg gravity-correction factor in Sweden for Acts 6 and 7.
No wonder we feel lighter here in Valencia than we did in Hamburg. And we thought it was the Spanish cuisine.
The TD has already announced that there will be no "gravity-correction factor" for Trapani. It has essentially the same gravity as Valencia where the yachts were all originally measured.
The ACC rule, however, has always had a correction factor for the specific gravity of the water in which a yacht is measured. Archimedes must have made a bigger impression on the rules writers than did Sir Isaac.
Perhaps, then, while in Trapani we should celebrate Sicily's famous native-son/mathematician by referring to the TD, with even more reverence if not gravitas than usual, as Ken "Archimedes" McAlpine.
Finally, and we have researched this thoroughly -- there is no truth whatsoever to a supposed historical footnote being offered around by that ersatz student of Sicilian history, Peter "Luiggi" Reggio, that right after Archimedes hollered, "Eureka," his wife muttered, "Whatever floats your boat."
Source (for the important stuff): "Archimedes." The Columbia Electronic Encyclopedia, Sixth Edition. Columbia University Press., 2003. Answers.com GuruNet Corp. 19 Sep. 2005.
TD Ken McAlpine checking the gravity in Malmö. Now the measurers
take into account Newton's Laws as well as Archimedes' principles.
Archimedes
In one, he was asked by Hiero II, the Greek ruler of Sicily, to determine whether a crown was pure gold or was alloyed with silver. Archimedes was perplexed, until one day, observing the overflow of water in his bath, he suddenly realized that since gold is more dense (i.e., has more weight per volume) than silver, a given weight of gold represents a smaller volume than an equal weight of silver, and that a given weight of gold would therefore displace less water than an equal weight of silver. Delighted at his discovery, he ran home without his clothes, shouting “Eureka,” which means “I have found it.” He found that Hiero's crown displaced more water than an equal weight of gold, thus showing that the crown had been alloyed with silver (or another metal less dense than gold).
In the other story Archimedes is said to have told Hiero, in illustration of the principle of the lever, “Give me a place to stand, and I will move the world.” Even that ties in to the Cup -- reminding some of us of a few former AC designers who made similar promises at the outset of their campaigns, but, sadly, were able to leverage neither their standing nor their syndicate's ample resources.
No doubt the naval architects and other AC technical types can explain better than I the significance of Archimedes' discoveries about density and buoyancy -- and how they directly relate to the America's Cup. Suffice to say that two of the three main factors of the AC Class Rule-formula are directly related: a yacht's Displacement and it's waterline Length while floating in still water and in measurement trim. (The third factor is Sail Area.)
A yacht's Displacement will vary slightly but significantly with the density (ok, specific gravity) of the local water. Accordingly the Length will vary -- if the yacht sinks lower its waterline grows longer; floats higher, shorter. Hence the need for a correction factor when the measurers "float the boat" in waters of differing salinity, which, of course, affects the specific gravity of the water. Needless to say, the salinity of sea (and lake) water varies significantly from place to place around the world.
All that to say nothing of the technical teams being guided by Archimedes' principles in designing the yachts to fit within the Rule in the first place.
In Malmö our ACC Technical Director ("TD") might have been dubbed Ken "Newton" McAlpine. It was there that Ken and his measurement team used, for the first time in the history of the Cup, a gravity factor. Why?
Sir Isaac Newton
The earth is not a perfect sphere but a bit squashed at the poles and bulging at the beltline (seems age has a way of doing that to the best of us). Accordingly, the closer you are to the Poles the closer you are to the center of the earth; and the closer to the earth's dense core, the more gravitational attraction. So, nearer the Poles things weigh more than near the Equator (all other things being equal like your height above sea level and the local geophysics). [22 Sep update -- please also note the interesting comment by Frank Albina, below, about the centrifugal force factor.]
In a nutshell, when the yachts were re-weighed in Malmö it was soon realized that at least those which had not been changed in any way all weighed slightly more than they had in Valencia, hence the use of a scientifically-derived 50kg gravity-correction factor in Sweden for Acts 6 and 7.
No wonder we feel lighter here in Valencia than we did in Hamburg. And we thought it was the Spanish cuisine.
The TD has already announced that there will be no "gravity-correction factor" for Trapani. It has essentially the same gravity as Valencia where the yachts were all originally measured.
The ACC rule, however, has always had a correction factor for the specific gravity of the water in which a yacht is measured. Archimedes must have made a bigger impression on the rules writers than did Sir Isaac.
Perhaps, then, while in Trapani we should celebrate Sicily's famous native-son/mathematician by referring to the TD, with even more reverence if not gravitas than usual, as Ken "Archimedes" McAlpine.
Finally, and we have researched this thoroughly -- there is no truth whatsoever to a supposed historical footnote being offered around by that ersatz student of Sicilian history, Peter "Luiggi" Reggio, that right after Archimedes hollered, "Eureka," his wife muttered, "Whatever floats your boat."
Source (for the important stuff): "Archimedes." The Columbia Electronic Encyclopedia, Sixth Edition. Columbia University Press., 2003. Answers.com GuruNet Corp. 19 Sep. 2005.
TD Ken McAlpine checking the gravity in Malmö. Now the measurers
take into account Newton's Laws as well as Archimedes' principles.
by TFE
