Chapter 1 introduction to marine navigation definitions 100. The Art And Science Of Navigation

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110. The Time Sight

The theory of the time sight had been known to mathe- maticians since the development of spherical trigonometry, but not until the chronometer was developed could it be used by mariners.

The time sight used the modern navigational triangle. The codeclination, or polar distance, of the body could be deter- mined from the almanac. The zenith distance (coaltitude) was determined by observation. If the colatitude were known, three

sides of the triangle were available. From these the meridian angle was computed. The comparison of this with the Green- wich hour angle from the almanac yielded the longitude.

The time sight was mathematically sound, but the navigator was not always aware that the longitude determined was only as accurate as the latitude, and together they merely formed a point on what is known today as a line of position. If the observed body was on the prime vertical, the line of position ran north and south and a small error in latitude generally had little effect on the longitude. But when the body was close to the meridian, a small error in latitude produced a large error in longitude.

The line of position by celestial observation was un- known until discovered in 1837 by 30-year-old Captain Thomas H. Sumner, a Harvard graduate and son of a United States congressman from Massachusetts. The discovery of the “Sumner line,” as it is sometimes called, was consid- ered by Maury “the commencement of a new era in practical navigation.” This was the turning point in the de- velopment of modern celestial navigation technique. In Sumner’s own words, the discovery took place in this manner:

Having sailed from Charleston, S. C., 25th November, 1837, bound to Greenock, a series of heavy gales from the Westward promised a quick passage; after passing the Azores, the wind prevailed from the Southward, with thick weather; after passing Longitude 21°W, no observation was had until near the land; but soundings were had not far, as was supposed, from the edge of the Bank. The weather was now more boisterous, and very thick; and the wind still Southerly; arriving about midnight, 17th December, within 40 miles, by dead reckoning, of Tusker light; the wind hauled SE, true, making the Irish coast a lee shore; the ship was then kept close to the wind, and several tacks made to preserve her position as nearly as possible until daylight; when nothing being in sight, she was kept on ENE under short sail, with heavy gales; at about 10 AM an altitude of the sun was observed, and the Chronometer time noted; but, having run so far without any observation, it was plain the Latitude by dead reckoning was liable to error, and could not be entirely relied on. Using, however, this Lati- tude, in finding the Longitude by Chronometer, it was found to put the ship 15' of Longitude E from her position by dead reckoning; which in Latitude 52°N is 9 nautical miles; this seemed to agree tolerably well with the dead reckoning; but feeling doubtful of the Latitude, the observa- tion was tried with a Latitude 10' further N, finding this placed the ship ENE 27 nautical miles, of the former posi- tion, it was tried again with a Latitude 20' N of the dead reckoning; this also placed the ship still further ENE, and still 27 nautical miles further; these three positions were then seen to lie in the direction of Small’s light.

It then at once appeared that the observed altitude must have happened at all the three points, and at Small’s light, and at the ship, at the same instant of time;



Figure 110. The first celestial line of position, obtained by Captain Thomas Sumner in 1837.

and it followed, that Small’s light must bear ENE, if the Chronometer was right. Having been convinced of this truth, the ship was kept on her course, ENE, the wind being still SE., and in less than an hour, Small’s light was made bearing ENE 1/2 E, and close aboard.

In 1843 Sumner published a book, A New and Accurate Method of Finding a Ship’ s Position at Sea by Projection on Mercator’s Chart. He proposed solving a single time sight twice, using latitudes somewhat greater and somewhat less than that arrived at by dead reckoning, and joining the two positions obtained to form the line of position.

The Sumner method required the solution of two time sights to obtain each line of position. Many older navigators preferred not to draw the lines on their charts, but to fix their position mathematically by a method which Sumner had also devised and included in his book. This was a tedious but popular procedure.

111. Navigational Tables

Spherical trigonometry is the basis for solving every navigational triangle, and until about 80 years ago the nav-

igator had no choice but to solve each triangle by tedious, manual computations.

Lord Kelvin, generally considered the father of modern navigational methods, expressed interest in a book of tables with which a navigator could avoid tedious trigonometric solutions. However, solving the many thousands of triangles involved would have made the project too costly. Computers finally pro- vided a practical means of preparing tables. In 1936 the first volume of Pub. No. 214 was made available; later, Pub. No. 249 was provided for air navigators. Pub. No. 229, Sight Reduction Tables for Marine Navigation, has replaced Pub. No. 214.

Modern calculators are gradually replacing the tables. Scientific calculators with trigonometric functions can easi- ly solve the navigational triangle. Navigational calculators readily solve celestial sights and perform a variety of voyage planning functions. Using a calculator generally gives more accurate lines of position because it eliminates the rounding errors inherent in tabular inspection and interpolation.

112. Electronics And Navigation

Perhaps the first application of electronics to naviga- tion involved sending telegraphic time signals in 1865 to


check chronometer error. Transmitting radio time signals for at sea chronometer checks dates to 1904.

Radio broadcasts providing navigational warnings, be- gun in 1907 by the U.S. Navy Hydrographic Office, helped increase the safety of navigation at sea.

By the latter part of World War I the directional prop- erties of a loop antenna were successfully used in the radio direction finder. The first radiobeacon was installed in 1921. Early 20th century experiments by Behm and Lan- gevin led to the U.S. Navy’s development of the first practical echo sounder in 1922.

Today, electronics touches almost every aspect of navi- gation. Hyperbolic systems, satellite systems, and electronic charts all require an increasingly sophisticated electronics suite. These systems’ accuracy and ease of use make them in- valuable assets to the navigator. Indeed, it is no exaggeration to state that, with the advent of the electronic chart and dif- ferential GPS, the mariner will soon be able to navigate from port to port using electronic navigation equipment alone.

113. Development Of Radar

As early as 1904, German engineers were experimenting with reflected radio waves. In 1922 two American scientists, Dr. A. Hoyt Taylor and Leo C. Young, testing a communica- tion system at the Naval Aircraft Radio Laboratory, noted fluctuations in the signals when ships passed between stations on opposite sides of the Potomac River. In 1935 the British be- gan work on radar. In 1937 the USS Leary tested the first sea- going radar. In 1940 United States and British scientists com- bined their efforts. When the British revealed the principle of the multicavity magnetron developed by J. T. Randall and H. A. H. Boot at the University of Birmingham in 1939, micro- wave radar became practical. In 1945, at the close of World War II, radar became available for commercial use.

114. Development Of Hyperbolic Radio Aids

V arious hyperbolic systems were developed from World War II, including Loran A. This was replaced by the more accurate Loran C system in use today. Using very low frequencies, the Omega navigation system provides world- wide, though less accurate, coverage for a variety of applications including marine navigation. Various short range and regional hyperbolic systems have been devel- oped by private industry for hydrographic surveying, offshore facilities positioning, and general navigation.

115. Other Electronic Systems

The Navy Navigation Satellite System (NAVSAT) fulfilled a requirement established by the Chief of Naval Op- erations for an accurate worldwide navigation system for all naval surface vessels, aircraft, and submarines. The system was conceived and developed by the Applied Physics Labo- ratory of The Johns Hopkins University. The underlying concept that led to development of satellite navigation dates to 1957 and the first launch of an artificial satellite into orbit. NAVSAT has been replaced by the far more accurate and widely available Global Positioning System (GPS).

The first inertial navigation system was developed in 1942 for use in the V2 missile by the Peenemunde group under the leadership of Dr. Wernher von Braun. This system used two 2-degree-of-freedom gyroscopes and an integrating accelerom- eter to determine the missile velocity. By the end of World War II, the Peenemunde group had developed a stable platform with three single-degree-of-freedom gyroscopes and an integrating accelerometer. In 1958 an inertial navigation system was used to navigate the USS Nautilus under the ice to the North Pole.


116. Governmental Roles

Navigation only a generation ago was an independent process, carried out by the mariner without outside assis- tance. With compass and charts, sextant and chronometer, he could independently travel anywhere in the world. The increasing use of electronic navigation systems has made the navigator dependent on many factors outside his con- trol. Government organizations fund, operate, and regulate satellites, Loran, and other electronic systems. Govern- ments are increasingly involved in regulation of vessel movements through traffic control systems and regulated areas. Understanding the governmental role in supporting and regulating navigation is vitally important to the mari- ner. In the United States, there are a number of official organizations which support the interests of navigators. Some have a policy-making role; others build and operate

navigation systems. Many maritime nations have similar organizations performing similar functions. International organizations also play a significant role.

117. The Coast And Geodetic Survey

The U.S. Coast and Geodetic Survey was founded in 1807 when Congress passed a resolution authorizing a sur- vey of the coast, harbors, outlying islands, and fishing banks of the United States. President Thomas Jefferson ap- pointed Ferdinand Hassler, a Swiss immigrant and professor of mathematics at West Point, the first Director of the “Survey of the Coast.” The survey became the “Coast Survey” in 1836.

The approaches to New York were the first sections of the coast charted, and from there the work spread northward and southward along the eastern seaboard. In 1844 the work



was expanded and arrangements made to chart simultaneous- ly the gulf and east coasts. Investigation of tidal conditions began, and in 1855 the first tables of tide predictions were published. The California gold rush necessitated a survey of the west coast. This survey began in 1850, the year California became a state. Coast Pilots, or Sailing Directions, for the At- lantic coast of the United States were privately published in the first half of the 19th century. In 1850 the Survey began accumulating data that led to federally produced Coast Pilots. The 1889 Pacific Coast Pilot was an outstanding contribution to the safety of west coast shipping.

In 1878 the survey was renamed “Coast and Geodetic Survey.” In 1970 the survey became the “National Ocean Survey,” and in 1983 it became the “National Ocean Ser- vice.” The Office of Charting and Geodetic Services accomplished all charting and geodetic functions. In 1991 the name was changed back to the original “Coast and Geo- detic Survey,” organized under the National Ocean Service along with several other environmental offices. Today it provides the mariner with the charts and coast pilots of all waters of the United States and its possessions, and tide and tidal current tables for much of the world. Its administrative order requires the Coast and Geodetic Survey to plan and direct programs to produce charts and related information for safe navigation of the Nation’s waterways, territorial seas, and national airspace. This work includes all activities related to the National Geodetic Reference System; survey- ing, charting, and data collection; production and distribution of charts; and research and development of new technologies to enhance these missions.

118. The Defense Mapping Agency

In the first years of the newly formed United States of America, charts and instruments used by the Navy and mer- chant mariners were left over from colonial days or were obtained from European sources. In 1830 the U.S. Navy es- tablished a “Depot of Charts and Instruments” in Washington, D. C. It was a storehouse from which available charts, sailing directions, and navigational instruments were issued to Naval ships. Lieutenant L. M. Goldsborough and one assistant, Passed Midshipman R. B. Hitchcock, constituted the entire staff.

The first chart published by the Depot was produced from data obtained in a survey made by Lieutenant Charles Wilkes, who had succeeded Goldsborough in 1834. Wilkes later earned fame as the leader of a United States expedition to Antarctica. From 1842 until 1861 Lieutenant Matthew Fontaine Maury served as Officer in Charge. Under his command the Depot rose to international prominence. Maury decided upon an ambitious plan to increase the mar- iner’s knowledge of existing winds, weather, and currents. He began by making a detailed record of pertinent matter included in old log books stored at the Depot. He then inau- gurated a hydrographic reporting program among shipmasters, and the thousands of reports received, along

with the log book data, were compiled into the “Wind and Current Chart of the North Atlantic” in 1847. This is the an- cestor of today’s Pilot Chart. The United States instigated an international conference in 1853 to interest other nations in a system of exchanging nautical information. The plan, which was Maury’s, was enthusiastically adopted by other maritime nations. In 1854 the Depot was redesignated the “U.S. Naval Observatory and Hydrographical Office.” In 1861, Maury, a native of Virginia, resigned from the U.S. Navy and accepted a commission in the Confederate Navy at the beginning of the Civil War. This effectively ended his career as a navigator, author, and oceanographer. At war’s end, he fled the country. Maury’s reputation suffered from his embracing the Confederate cause. In 1867, while Maury was still absent from the country to avoid arrest for treason, George W. Blunt, an editor of hydrographic publications, wrote:

In mentioning what our government has done to- wards nautical knowledge, I do not allude to the works of Lieutenant Maury, because I deem them worthless. . . . They have been suppressed since the rebellion by order of the proper authorities, Maury’s loyalty and hydrography being alike in quality.

After Maury’s return to the United States in 1868, he served as an instructor at the Virginia Military Institute. He continued at this position until his death in 1873. Since his death, his reputation as one of America’s greatest hydrog- raphers has been restored.

In 1866 Congress separated the Observatory and the Hydrographic Office, broadly increasing the functions of the latter. The Hydrographic Office was authorized to carry out surveys, collect information, and print every kind of nautical chart and publication “for the benefit and use of navigators generally.”

The Hydrographic Office purchased the copyright of The New American Practical Navigator in 1867. The first Notice to Mariners appeared in 1869. Daily broadcast of navigational warnings was inaugurated in 1907. In 1912, following the sinking of the Titanic, the International Ice Patrol was established.

In 1962 the U.S. Navy Hydrographic Office was redes- ignated the U.S. Naval Oceanographic Office. In 1972 certain hydrographic functions of the latter office were transferred to the Defense Mapping Agency Hydrograph- ic Center. In 1978 the Defense Mapping Agency Hydrographic/Topographic Center (DMAHTC) as- sumed hydrographic and topographic chart production functions. DMAHTC provides support to the U.S. Depart- ment of Defense and other federal agencies on matters concerning mapping, charting, and geodesy. It continues to fulfill the old Hydrographic Office’s responsibilities to “navigators generally.”


119. The United States Coast Guard

Alexander Hamilton established the U.S. Coast Guard as the Revenue Marine, later the Revenue Cutter Service, on August 4, 1790. It was charged with enforcing the customs laws of the new nation. A revenue cutter, the Harriet Lane, fired the first shot from a naval unit in the Civil War at Fort Sumter. The Revenue Cutter Service be- came the U.S. Coast Guard when combined with the Lifesaving Service in 1915. The Lighthouse Service was added in 1939, and the Bureau of Marine Inspection and Navigation was added in 1942. The Coast Guard was transferred from the Treasury Department to the Depart- ment of Transportation in 1967.

The primary functions of the Coast Guard include mar- itime search and rescue, law enforcement, and operation of the nation’s aids to navigation system. In addition, the Coast Guard is responsible for port safety and security, merchant marine inspection, and marine pollution control. The Coast Guard operates a large and varied fleet of ships, boats, and aircraft in performing its widely ranging duties.

Navigation systems operated by the Coast Guard in- clude the system of some 40,000 lighted and unlighted beacons, buoys, and ranges in U.S. waters; the U.S. stations of the Loran C system; the Omega navigation system; ra- diobeacons and racons; differential GPS (DGPS) services in the U.S.; and Vessel Traffic Services (VTS) in major ports and harbors of the U.S.

120. The United States Navy

The U.S. Navy was officially established in 1798. Its role in the development of navigational technology has been singular. From the founding of the Naval Observatory to the development of the most advanced electronics, the U.S. Navy has been a leader in developing devices and techniques designed to make the navigator’s job safer and easier.

The development of almost every device known to navigation science has been deeply influenced by Naval policy. Some systems are direct outgrowths of specific Naval needs; some are the result of technological im- provements shared with other services and with commercial maritime industry.

121. The United States Naval Observatory

One of the first observatories in the United States was built in 1831-1832 at Chapel Hill, N.C. The Depot of Charts and Instruments, established in 1830, was the agency from which the U.S. Navy Hydrographic Office and the U.S. Na- val Observatory evolved 36 years later. Under Lieutenant Charles Wilkes, the second Officer in Charge, the Depot about 1835 installed a small transit instrument for rating chronometers.

The Mallory Act of 1842 provided for the establish- ment of a permanent observatory. The director was

authorized to purchase everything necessary to continue as- tronomical study. The observatory was completed in 1844 and the results of its first observations were published two years later. Congress established the Naval Observatory as a separate agency in 1866. In 1873 a refracting telescope with a 26 inch aperture, then the world’s largest, was in- stalled. The observatory, located in Washington, D.C., has occupied its present site since 1893.

122. The Royal Greenwich Observatory

England had no early privately supported observatories such as those on the continent. The need for navigational advancement was ignored by Henry VIII and Elizabeth I, but in 1675 Charles II, at the urging of John Flamsteed, Jo- nas Moore, Le Sieur de Saint Pierre, and Christopher Wren, established the Greenwich Royal Observatory. Charles limited construction costs to £500, and appointed Flam- steed the first Astronomer Royal, at an annual salary of £100. The equipment available in the early years of the ob- servatory consisted of two clocks, a “sextant” of 7 foot radius, a quadrant of 3 foot radius, two telescopes, and the star catalog published almost a century before by Tycho Brahe. Thirteen years passed before Flamsteed had an in- strument with which he could determine his latitude accurately.

In 1690 a transit instrument equipped with a telescope and vernier was invented by Romer; he later added a vertical circle to the device. This enabled the astronomer to deter- mine declination and right ascension at the same time. One of these instruments was added to the equipment at Greenwich in 1721, replacing the huge quadrant previously used. The development and perfection of the chronometer in the next hundred years added to the accuracy of observations.

Other national observatories were constructed in the years that followed: at Berlin in 1705, St. Petersburg in 1725, Palermo in 1790, Cape of Good Hope in 1820, Parra- matta in New South Wales in 1822, and Sydney in 1855.

123. The International Hydrographic Organization

The International Hydrographic Organization (IHO) was originally established in 1921 as the Internation- al Hydrographic Bureau (IHB). The present name was adopted in 1970 as a result of a revised international agree- ment among member nations. However, the former name, International Hydrographic Bureau, was retained for the IHO’s administrative body of three Directors and a small staff at the organization’s headquarters in Monaco.

The IHO sets forth hydrographic standards to be agreed upon by the member nations. All member states are urged and encouraged to follow these standards in their sur- veys, nautical charts, and publications. As these standards are uniformly adopted, the products of the world’s hydro- graphic and oceanographic offices become more uniform. Much has been done in the field of standardization since the



Bureau was founded. The principal work undertaken by the IHO is:

• To bring about a close and permanent association be- tween national hydrographic offices.

• To study matters relating to hydrography and allied sciences and techniques.

• Tofurthertheexchangeofnauticalchartsanddocu- ments between hydrographic offices of member governments.

• Tocirculatetheappropriatedocuments. • To tender guidance and advice upon request, in par- ticular to countries engaged in setting up or

expanding their hydrographic service. • To encourage coordination of hydrographic surveys

with relevant oceanographic activities. • To extend and facilitate the application of oceano-

graphic knowledge for the benefit of navigators. • To cooperate with international organizations and scientific institutions which have related objectives.

During the 19th century, many maritime nations estab- lished hydrographic offices to provide means for improving the navigation of naval and merchant vessels by providing nautical publications, nautical charts, and other navigation- al services. There were substantial differences in hydrographic procedures, charts, and publications. In 1889, an International Marine Conference was held at Washing- ton, D. C., and it was proposed to establish a “permanent international commission.” Similar proposals were made at the sessions of the International Congress of Navigation held at St. Petersburg in 1908 and again in 1912.

In 1919 the hydrographers of Great Britain and France cooperated in taking the necessary steps to convene an in- ternational conference of hydrographers. London was selected as the most suitable place for this conference, and on July 24, 1919, the First International Conference opened, attended by the hydrographers of 24 nations. The object of the conference was “To consider the advisability of all maritime nations adopting similar methods in the preparation, construction, and production of their charts and all hydrographic publications; of rendering the results in the most convenient form to enable them to be readily used; of instituting a prompt system of mutual exchange of hydrographic information between all countries; and of providing an opportunity to consultations and discussions to be carried out on hydrographic subjects generally by the hydrographic experts of the world.” This is still the major purpose of the International Hydrographic Organization.

As a result of the conference, a permanent organization was formed and statutes for its operations were prepared. The International Hydrographic Bureau, now the International Hy- drographic Organization, began its activities in 1921 with 18 nations as members. The Principality of Monaco was selected because of its easy communication with the rest of the world and also because of the generous offer of Prince Albert I of

Monaco to provide suitable accommodations for the Bureau in the Principality. There are currently 59 member governments. Technical assistance with hydrographic matters is available through the IHO to member states requiring it.

Many IHO publications are available to the general public, such as the International Hydrographic Review, In- ternational Hydrographic Bulletin, Chart Specifications of the IHO, Hydrographic Dictionary, and others. Inquiries should be made to the International Hydrographic Bureau, 7 Avenue President J. F. Kennedy, B.P. 445, MC98011, Monaco, CEDEX.

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