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History of Hydrographic Surveying
The original U.S. Coast Survey emblem was used on charts beginning in the 1830s.


Although the history of hydrography is nearly as old as sailing, in the United States it officially began on February 10, 1807. The Coast Survey ‒ the oldest scientific agency in the U.S. ‒ was established when President Thomas Jefferson and Congress authorized a “survey to be taken of coasts of the United States."

The first Superintendent of the Coast Survey was Ferdinand Rudolph Hassler, who brought together mathematicians, cartographers, geodesists, meterologists, hydrographers, topographers, sailors, laborers, and administrators to survey and chart the coast of the United States.


The first official hydrographic survey in the U.S. was conducted along the south shore of Long Island in 1834. Five years later, in 1839, the U.S. government produced its first nautical chart.
Drawing of a sailor getting ready to toss a leadline from the mast of a sailing ship.

Early hydrographic surveys consisted of depths measured by sounding pole and hand lead line, with positions determined by three-point sextant fixes to mapped reference points. Lead lines were ropes, or lines, with depth markings and lead weights attached, and these lines were lowered and read manually in a labor-intensive and time-consuming process. While the initial depth soundings may have been accurate, they were limited in number, and thus, coverage between single soundings was lacking.


3-D cutaway showing vessels engaged in wire drag operations.  Wire can be seen being dragged under water. In 1904, weighted wire-drag surveys were introduced into hydrography, wherein a wire attached to two vessels was dragged between two points. If the wire (set at a certain depth by a system of weights and buoys) encountered an obstruction, it would become taut and form a "V," revealing the depth and position of submerged rocks and other obstructions.
Black and White picture of Herbert Grove Dorsey next to his invention--Dorsey Fathometer. The 1930s saw the development and implementation of single-beam echo sounders that used sound to measure the distance of the sea floor directly below a vessel. By running a series of lines at a specified spacing, single beam echo sounders and fathometers greatly increased the speed of the survey process by allowing more data points to be collected. However, this method still left gaps in quantitative depth information between survey lines.
Depth finding techniques over the years: 1)Leadline (pre-1940) being used by ship; 2) Single Beam (1940's-1980's) Echo sounder sounding continuously under ship. 3) Multibeam(1990's to present) swath being sounded under ship. In  the 1950s, 1960s, and 1970s, a number of evolutionary concepts were advanced that fundamentally changed how we look at and map the seafloor. Side scan sonar technology offered a qualitative means of obtaining the sonic equivalent of an aerial photograph and improved the ability to identify submerged wrecks and obstructions. Multibeam swath systems made it possible to obtain quantitative depth information for 100 percent of the bottom in a survey area.

Hydrographic surveying techniques and procedures continue to evolve and The Office of Coast Survey continues to research and evaluate emerging technologies.

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