History and Progression

Multibeam echosounders, also known as Swathe (British English) or Swath (American English) echosounders, originated in the late 1950s, originally for military applications. They were developed in the 1970s by the US Navy

United States Navy

The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

, in conjunction with General Instruments to map large swaths of the ocean floor

Seabed

The seabed is the bottom of the ocean.- Ocean structure :Most of the oceans have a common structure, created by common physical phenomena, mainly from tectonic movement, and sediment from various sources...

 to assist the underwater navigation of its submarine

Submarine

A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

 force. Starting in the 1970s, companies such as General Instruments (now SeaBeam Instruments, part of L3/Klein) in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, Krupp Atlas (now Atlas Hydrographic

Atlas Hydrographic

ATLAS Hydrographic is a hydrographic and oceanographic systems company, part of the ATLAS Elektronik group that is owned by ThyssenKrupp and EADS....

) and Elac Nautik (now part of L3 Communications) in Germany

Germany

Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

, Simrad (now Kongsberg Maritime

Kongsberg Maritime

Kongsberg Maritime is a Norwegian technology enterprise within the Kongsberg Gruppen . Kongsberg Maritime deliver systems for positioning, surveying, navigation and automation to merchant vessels and offshore installations...

) in Norway

Norway

Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...

 and RESON in Denmark

Denmark

Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...

 developed systems that could be mounted to the hull of large ship

Ship

Since the end of the age of sail a ship has been any large buoyant marine vessel. Ships are generally distinguished from boats based on size and cargo or passenger capacity. Ships are used on lakes, seas, and rivers for a variety of activities, such as the transport of people or goods, fishing,...

s, and then small boat

Boat

A boat is a watercraft of any size designed to float or plane, to provide passage across water. Usually this water will be inland or in protected coastal areas. However, boats such as the whaleboat were designed to be operated from a ship in an offshore environment. In naval terms, a boat is a...

s (as technologies improved and operating frequencies increased).

The first commercial multibeam is now known as the SeaBeam Classic and was put in service in May 1977 (Farr, Marine Geodesy, Volume 4, Issue 2 1980 , pages 77 – 93) on the Australian survey vessel HMAS Cook. This system produced up to 16 beams across a 45-degree swath.

The second SeaBeam Classic installation was on the French Research Vessel Jean Charcot sometime after the Cook. The SB Classic arrays on the Charcot were damaged in a grounding and the SeaBeam was replaced with an EM120 in 1991. Although it seems that the original SeaBeam Classic installation was not used much, the others were widely used, and subsequent installations were made on many vessels.

SeaBeam Classic systems were subsequently installed on the US academic Research Vessels Thomas Washington (Scripps Institution of Oceanography, University of California), the Robert D. Conrad (Lamont-Doherty Earth Observatory of Columbia University) and the Atlantis II (Woods Hole Oceanographic Institution.)

The (retronym

Retronym

A retronym is a type of neologism that provides a new name for an object or concept to differentiate the original form or version of it from a more recent form or version. The original name is most often augmented with an adjective to account for later developments of the object or concept itself...

) term "SeaBeam Classic" was coined after the manufacturer developed newer systems such as the SeaBeam 2000 and the SeaBeam 2112 in the late 1980s.

As technology improved in the 1980s and 1990s, higher-frequency systems suitable for high-resolution mapping in shallow water were developed, and such systems are widely used for shallow-water hydrographic surveying

Hydrography

Hydrography is the measurement of the depths, the tides and currents of a body of water and establishment of the sea, river or lake bed topography and morphology. Normally and historically for the purpose of charting a body of water for the safe navigation of shipping...

 in support of navigational charting

Nautical chart

A nautical chart is a graphic representation of a maritime area and adjacent coastal regions. Depending on the scale of the chart, it may show depths of water and heights of land , natural features of the seabed, details of the coastline, navigational hazards, locations of natural and man-made aids...

. Multibeam echosounders are also commonly used for geological

Marine geology

Marine geology or geological oceanography involves geophysical, geochemical, sedimentological and paleontological investigations of the ocean floor and coastal margins...

 and oceanographic

Oceanography

Oceanography , also called oceanology or marine science, is the branch of Earth science that studies the ocean...

 research, and since the 1990s for offshore oil and gas exploration

Exploration

Exploration is the act of searching or traveling around a terrain for the purpose of discovery of resources or information. Exploration occurs in all non-sessile animal species, including humans...

 and seafloor cable routing.

In 1989, Atlas Electronics (Bremen, Germany) installed a second-generation deep-sea multibeam called Hydrosweep DS on the German research vessel Meteor. The Hydrosweep DS (HS-DS) produced up to 59 beams across a 90-degree swath, which was a vast improvement and was inherently ice-strengthened. Early HS-DS systems were installed on the Meteor (Germany), the Polarstern (Germany), the Maurice Ewing (US) and the Sagar Kanya (India) in 1989 and 1990 and subsequently on a number of other vessels including the Thomas Thompson (US) and Hakurei Maru (Japan.)

As the cost of components has decreased, the number of multibeam systems sold and in operation worldwide has increased significantly. Smaller, portable systems can be operated on a small launch or tender vessel unlike the older systems that required considerable time and effort to attach to a ship's hull. Some multibeam echosounders such as the Teledyne Odom ES3 also incorporate a motion sensor at the face of the acoustic transducer, allowing even faster installation on small vessels. Multibeam echosounders like this are allowing many smaller hydrographic survey companies to move from traditional single beam echosounders to swath systems.

Theory of Operation

A multibeam echosounder is a device typically used by hydrographic surveyors to determine the depth of water and the nature of the seabed. Most modern systems work by transmitting a broad acoustic pulse from a specially designed transducer

Transducer

A transducer is a device that converts one type of energy to another. Energy types include electrical, mechanical, electromagnetic , chemical, acoustic or thermal energy. While the term transducer commonly implies the use of a sensor/detector, any device which converts energy can be considered a...

across the full swath acrosstrack then forming a receive beam that is much narrower (around 1 degree depending on the system) to establish a two way travel time of the acoustic pulse. If the speed of sound in water is known for the full water column, the depth and position of the return signal can be determined from the receive angle and the two-way travel time.

In order to determine the transmit and receive angle of each beam, a multibeam echosounder requires accurate measurement of the motion of the sonar relative to a cartesian coordinate system. The measured values are typically heave, pitch, roll, and heading.

External links

• Echoscope
• Teledyne Odom
• Seabeam Instruments
• Atlas Hydrographic
• Kongsberg Multibeams
• Reson SeaBat
• Elac Multibeam Sonars
• MB-System open source software for processing multibeam data
• News and application articles of multibeam equipment on Hydro International; Product Survey Multibeam Shallow Water; Product Survey Multibeam Deep Water
• Tritech International Ltd