Surveys are conducted by the U.S. Navy and civilian government agencies. By their nature, surveys are systematic examinations of the oceans' condition. Although the methods used to conduct these studies have evolved over the last two centuries, expressions such as "sailing in uncharted waters" and "seizing the weather gauge" still attest to their importance.
Early Surveys
All mariners know that accurate information about winds, tides, currents, and ocean bottom depth raise the likelihood of a safe passage. In naval terms, superior "environmental intelligence" can allow one side to gain advantage over the other. In the nation's early years, this knowledge was held by individual seafarers and naval officers, or published, with varying degrees of accuracy, by foreign countries and private commercial operations. In 1807, Congress authorized the creation of a Survey of the Coast to obtain and map basic information about the nation's islands, shoals, and anchorages. The U.S. Navy established the Depot of Charts and Instruments in 1830 to supply accurate nautical charts, books, and navigational instruments to the Navy and American shipping interests. The navy published its first charts in 1837, four maps of the fishing banks off the coast of Massachusetts.
In the 1840s, the practice of oceanographic surveying took a significant step forward on both the naval and civilian sides. Recognizing the need to keep all hydro-graphic (pertaining to nautical surveys and charts) materials in one place, in 1842 Congress authorized building a central repository for the Depot's collections. The Depot's superintendent, navy officer Matthew Fontaine Maury, made several key advances in the science of hydrography. First, he and his staff reviewed all of the hundreds of ships' logs in their care. By systematically comparing conditions for the same location in different seasons, Maury could suggest navigational routes that maximized speed and safety. The resulting Wind and Current Charts were soon the reference of choice worldwide. Maury also created a template for a standardized log that all navy captains were required to complete for every voyage and to submit to the Depot. Merchant and foreign vessels received copies of Wind and Current Charts as well in exchange for keeping Maury's logs. Within five years the Depot had received 26 million reports.
Meanwhile, Alexander Dallas Bache took the helm of the U.S. Coast Survey in 1843. Bache raised the level of scientific inquiry in the name of more accurate charts and navigation. His study of the gulf stream, begun in 1845, sought new measures to determine the dynamics of what he suspected was an ever-changing current. For more than a decade, survey ships repeatedly measured temperature at the surface and varying depths, described the bottom depth and character, recorded direction and speed of the currents and the surface and at varying depths, and examined plant and animal life along the way.
Technological Advances
Maury and Bache had laid the groundwork for American scientific exploration of the ocean. Their principle of repeated, systematic observation remains the guiding philosophy; only the tools have changed. In some instances, surveys have supported the deployment of new technologies. For example, entrepreneurs who wanted to set up a telegraph connection across the Atlantic required information about the ocean floor. The resulting survey produced the first published depth chart of the Atlantic Ocean, and in 1858 the first telegraphic messages were sent across the ocean via cable lying on the seabed.
New missions sometimes required new technologies. In the 1870s, Coast Survey officer Charles Sigsbee modified a prototype invented by Sir William Thomson (later Lord Kelvin) to construct a machine that used wire instead of rope to take depth soundings. Sigsbee's sounding machine was used to produce a bathymetric (deep-water depth) chart of the Gulf of Mexico in 1874–1875, the first modern and accurate map of any portion of the deep ocean. Sigsbee and biologist Alexander Agassiz collaborated to replace the rope used to raise and lower equipment with lines made of steel wire. Following this idea, Coast Survey officers developed steel wire lines that allowed vessels to anchor at abyssal depths.
By the 1870s, fish and shellfish stocks showed signs of decline and disputes arose among fishermen over the fairness of some of the new netting and dredging techniques. The Coast Survey worked with the newly created U.S. Fish Commission (1871) to conduct dredging operations of their own to survey fish populations. Coast Survey and Fisheries Commission ships discovered hundreds of marine species on their biological research expeditions crossing the world. In 1878, the Coast Survey merged with the Geodetic (size and shape of the earth) Survey to become the U.S. Coast and Geodetic Survey (C&GS), which began to produce the most complete and accurate maps yet of the United States.
During the last quarter of the nineteenth century, Navy oceanographers turned their attention to Central America, where they assisted in locating suitable sites for a canal linking the Gulf of Mexico and the Pacific Ocean, sparing ships the long and dangerous trip around the tip of South America. Nor had the government given up the idea of a Northwest Passage—a route linking the Atlantic and Pacific via the Arctic Sea. Several expeditions were sent to explore the ice; navy civil engineer Robert Peary reached the North Pole in 1909. The disastrous sinking of the Titanic in 1912 also focused new attention on monitoring ice from the polar sea.
During World War I (1914–1918), German submarines posed a new and frightening threat, sinking forty-five U.S. ships while cruising in American waters. American researchers pursued the idea of underwater listening devices as a way to track the U-boats, although the first workable system was not built until after the war. Sonar, the use of sound echoes to locate underwater features and submerged objects, revealed the sea bottom's topography in much greater detail than possible before. In the 1920s, C&GS vessels began to use echo-sounding equipment alongside the traditional wire line to determine accurate values for the velocity of sound in seawater. Survey ships mapped the terrain of the continental shelf, information that would prove valuable for hunting German submarines during World War II (1939–1945). On the eve of World War II, the navy explored the effects of water temperature and salinity on sound transmission underwater, further refining its ability to locate underwater targets.
World War II, and the renewed threat of submarine warfare, spurred more innovative firsts, including deep-sea cameras and electronic navigation systems that used reflected radio waves (radar). Intended originally as a tool in precision aerial bombing, radar was being used by the C&GS to conduct hydrographic surveys by the war's end. Demand for accurate charts had skyrocketed in the wake of Pearl Harbor. The navy's Hydrographic Office dispatched survey ships with onboard printing equipment to accompany the Pacific fleet—43 million charts were printed and issued in one year.
The decades after World War II were notable for collaboration between civilian government agencies, the C&GS, the navy, and academic institutions. One landmark expedition took place in 1955, when the C&GS ship Pioneer was engaged by the navy to survey the West Coast out to several hundred miles offshore. The Scripps Institute of Oceanography attached a newly designed tow to the Pioneer that would measure magnetic properties of the seabed. The project mapped previously unknown long, magnetic stripes that lay along the ocean floor. This discovery, along with the identification of the Mid-Atlantic Ridge Rift Valley in 1959, and C&GS scientists' studies of underwater earthquakes, ultimately led Princeton University professor Harry H. Hess to outline a theory of plate tectonics in the early 1960s.
The 1960s were a time of rapid advancement in oceanographic surveys. The C&GS built a fleet of new survey ships and spent more than a decade mapping large areas of the North Pacific basin for the Seamap Project. New technical advances included the Deep Tow instrument system, which takes multiple measures of the deep sea environment; multibeam sounding systems, which can take simultaneous readings of a swath of ocean floor to generate a map almost instantly; and the submersible re-search vessel Alvin, which can take scientists to unprecedented ocean depths. Research also focused on the inter-action between ocean and atmosphere, which was reflected in the creation of the National Oceanic and Atmospheric Administration (1970) that now encompasses the C&GS as well as the National Weather Service.
Technological advances of the late twentieth century included satellite communication and observation, global positioning, microchip technology, computers small enough to be taken into the field, and more sophisticated modeling techniques. One widely used practical application is the navy's Optimum Track Ship Routing program that uses meteorological and oceanographic data to create a near-real-time forecast of the safest and most efficient passage across the seas. Future surveys are likely to take advantage of microchip technology and satellite communication to obtain large-scale, real-time maps that use remote sensors to transmit data from a vast expanse of ocean. For instance, passive acoustic monitors positioned in the water all over the globe already have been used to detect deep-sea volcanic eruptions and the migratory paths of the blue whale. These technologies, along with even greater computer processing capability, may take oceanographers ever closer to obtaining a pulse of the planet.
Bibliography
Charts from the U.S. Coast Survey. Available from http://chartmaker.ncd.noaa.gov.
Labaree, Benjamin W., et al. America and the Sea: A Maritime History. Mystic, Conn.: Mystic Seaport Museum, 1998.
National Oceanic and Atmospheric Administration. Home page at http://oceanexplorer.noaa.gov.
Naval Oceanographic Office Home page at http://www.navo.navy.mil.
Pinsel, Marc I. 150 Years of Service on the Seas: A Pictorial History of the U.S. Naval Oceanographic Office from 1830 to 1980. Washington, D.C.: Department of the Navy, Oceanographic Office, 1982.
U.S. Department of Commerce, National Oceanic and Atmospheric Administration. Discovering Earth's Final Frontier: A U.S. Strategy for Ocean Exploration, The Report of the President's Panel on Ocean Exploration. Washington, D.C.: October 2000.
