In the later periods, the mariners succeeded in developing charts depicting distant shorelines and common features of the sea during voyages. According to historical records, such charts developed in the earlier period were marked with simple outlines of coastlines made to support written or oral directions. In addition to these, compasses, astrolabes, and callipers were the tools that were in use by ocean navigators in earlier times.
Primarily, this compass was used to determine the direction of the wind when the sun was not visible. Similarly, the cross-staff, astrolabe, and quadrant were in use to help sailors determine latitude in several stages of maritime navigation.
Phoenicians are the first Western civilization known to have developed the art of navigation at sea thousands of years ago. Phoenicians relied on primitive charts as well as observations of the Sun and stars to navigate their vessels to destinations. In the later period, the Phoenicians and their successors, the Carthaginians, also invented a tool known as the sounding weight.
Made of stone or lead, this bell-shaped tool had a very long rope attached to the tallow inside. Sailors used to lower this weight into the bottom of the sea to determine how deep the waters were, and, using this measurement, to estimate how far they were from the land. In addition, the tool, with the help of the tallow inside, could pick up sediments from the seabed, which enabled expert sailors to decide the location of their vessel. However, centuries passed before the use of a standard method to measure the distance and speed during navigation at sea.
A number of new techniques and methods were experimented with from time to time, making marine navigation more meaningful. Until the fifteenth century, coastal navigation was mostly in practice, since the open sea voyages were limited to regions of predictable winds and currents.
Further ventures by the sailors were enabled by the development of scientific and mathematically-based methods and tools in the following years. The invention of the sextant, the chip log and Chronometers, etc. And, the modern era saw the replacement of ancient navigational tools with electronic and technological equivalents and also the determination of standard measures including Prime Meridian. With the help of new technologies, from Gyroscopic Compass to GPS, now marine navigation has become more systematic and easy.
Years after the use of several techniques to determine the position and speed of a vessel, British mathematician Edmund Gunter succeeded in enhancing navigational tools including a new quadrant to define latitude at sea. The length equals about 1, meters at the poles and 1, meters at the equator. The term knot as it refers to the speed of ship, dates back to the s. A knot measures nautical miles per hour.
For example, a ship that is sailing at 10 knots, will do 10 nautical miles in an hour. Seventeenth-century mariners starting measuring the speed of their ships by using a common log. This tool was a coil of rope with equally spaced knots, attached to a piece of wood shaped like a slice of pie and weighted.
Dividing that The average of frequent measurements taken throughout the day proved to be a highly accurate reflection of how fast a ship was moving. The data was used to help them navigate by dead reckoning, the method used before the advent of modern instruments.
Today, maritime speed is determined by ultrasonic sensors or Doppler measurement, and the second divisor in the rate equation has been replaced by For more information about Amphibious Achievement, see the story about them in the June 19, , Boston Globe.
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