Thursday, June 23, 2016

Navigator's Week: Effective Nautical Interpretation

Today's entry in Navigator's Week comes to us from Robert Fryman, PhD, an adjunct professor at Georgia Perimeter College, reenactor with HMS Acasta, and veteran of the United States Coast Guard.

Effective nautical interpretation of the “Age of Sail” requires that the docent/reenactor go beyond proper clothing and appearance and the description of life at sea.  This is acutely important when describing and explaining the technological differences which exist between operating a vessel in the present as compared to the period from 1700 to 1815.  The procedures of navigation are illustrative of this, particularly as modern GPS systems have removed today’s travelers from the basic skills of map reading and plotting a course, yet such abilities would have been common place for sailors of the 18th and early 19th centuries.  Acquiring an applied knowledge of navigation skills therefore better prepares the interpreter/reenactor with not only a working understanding of the tools of navigation, but also an enhanced appreciation for sailors to perform complicated calculations without the benefit of electronic devices.

Detail from portrait of Master William Bligh,
John Webber, c. 1776, National Portrait Gallery (Australia)

Such an understanding of the tools and procedures of navigation was an integral component in the development of my interpretive persona as a member of the HMS Acasta.  I was able to approach this with a fundamental grounding in navigation gained while serving with the U.S: Coast Guard, but while the basic algorithms for plotting speed, distance, and position have remained the same, the tools for their calculation have not.  From reading period accounts of navigation procedures, the tools used for calculating the aforementioned variables, apart from the octant of sextant, included the sector, Günter Rule, dividers, parallel ruler, and tables of sines, cosines, and logarithms.  The sector and the Günter Rule were the equivalent of the 20th century slide rule, and both contained a number of different scales.  The user perform mathematical computations by placing the tips of a pair dividers on the appropriate scale.  Tables of sines, cosines, and logarithms were commonly found as appendices of mathematical treatises, such as the 1796 edition of John Love’s Geodesia and other publications including the American Coast Pilot, reducing the need for the navigator necessarily to be familiar with how to determine these values.

Detail from "His Royal Highness Prince William Henry," book illustration
for Hervey's Naval History, 1779, British Museum

While I re-learned the art of navigation from the 18th century perspective, I was suddenly struck by the differences that existed in the amount of formal training in mathematics that the sailor in 1790 received compared to that of your average middle school student of today, who by the 8th grade has already been taught Algebra and, in some instances Geometry.  This does not imply that today’s students are more intelligent than their 18th century counterparts, but rather serves to illustrate the impact of inexpensive electronic calculators in accelerating exposure to more advanced forms of mathematics than was previously possible.  I often present students in my Physical Science classes with a stimulated navigation problem where they must determine their position using paper reproductions of sectors.  The result of this exercise was that they gained an understanding of how people were able to solve problems using “primitive” technology while I was able to gain a new perspective on mathematical training of the 18th century sailor.

Through re-learning how to navigate using 18th century tools and equipment I was able to not only to better use the instruments and thus be better equipped to describe and explain their use and function to the public, but also gain a perspective onto the world of the 18th century sailor and his background which allowed him to perform such complicated calculations to venture to new lands.  This new information helps to explain to visitors the impact which modern technology has on the world of nautical navigation.

1 comment:

  1. I don't know if this study of navigation would have helped me figure out in high school Geometry why anyone would ever come up with sine, cosine and logarithms as of practical use, BUT-- now I think it may be fun to learn (tentatively!)for the navigational reason.