When a man has mastered the ability to travel by sea, he began to wonder what is the depth clearance under the keel and how to measure the depth. Initially, only coastal shipping was practiced. Cargo ship sailing, fishery, underwater scientific research, recreational diving as well as resource exploration and operation of submarine cables and pipelines laying were developing dynamically in this part of the continental shelf. That is why accurate bathymetric information was of great importance to masters, scientists, fishermen, ship-owners and all seafarers.
Cartographic compilation of even a primitive nautical chart was a huge challenge. It was a painstaking process and required, first and foremost, a large amount of data, which was primarily obtained through not efficient measurements. As technology progresses, new techniques and methods of ocean exploration have developed. The technology, systems, devices and instruments of underwater exploration have gone through a long way of change, modernization and improvements, ultimately creating the potential for a bottom surface visualization as three-dimensional spatial models. A significant role has been played by multibeam echosounder which revolutionized the hydrographic surveys and proved to be efficient means of hydrographic and oceanographic surveys.
Many surveying companies and maritime institutions are now using multibeam systems for their operations, either offshore or in coastal and inland waters. Since the time the first multibeam echosounder appeared (late 1970s) the technology has advanced enormously. Modern systems now boast far greater angular coverage (typically 120°-150°) and form hundreds of beams. Dual-head multibeam systems can potentially cover the entire sector (180°) underneath the ship. However surveyors must be aware that the outer beams of these acoustic systems return the most errors causing that the effective swath width is shorter than what the manufacturers declare. The paper presents the methods of estimating of effective (usable) swath width of dual-head multibeam echosounder EM 3002D. Results of the hydrographic survey performed by the polish navy survey ship ORP ‘Arctowski’ have been showed in the article.