Sonar is a technology that has been around for decades and relies on a fairly simple principle, but most people don’t recognize just how critical this technological advancement was to the Allied Forces in World War II. Who discovered sonar, and when was it first implemented?
Although the concept of sonar was theorized as early as 1822, sonar would not be converted into active, usable technology until 1916, when Canadian physicist Robert William Boyle produced a prototype that could effectively detect and range objects using sound.
There’s a lot of history behind sonar, and many great minds were involved in the invention of this technology that we take for granted today. The rest of this article will discuss the history of sonar and when it was first used.
The History of Sonar
The first recorded use of the technology behind sonar being used by humans was recorded in 1490 by Da Vinci when a tube placed in water was apparently able to detect approaching vessels when an ear was placed to the tube.
An application for this principle wasn’t considered until after the sinking of the Titanic disaster in 1912. Scientists and inventors were looking for a way to prevent that tragedy from ever happening again, and it was less than a year later that an echo-ranging device for use underwater was filed by Lewis Fry Richardson.
One year following, German physicist Alexander Behm followed suited and got a patent for his echo sounder.
Meanwhile, in Canada, Reginald Fessenden put his hand at designing a system that could communicate underwater, was capable of depth sounding, and could echo range at a distance of 2 miles (3.2 km).
The Fessenden oscillator, as it was called, couldn’t determine the precise bearing of an object, but it could indicate the presence of a potential hazard in the water. 10 British H-class submarines were launched with this designed oscillator on board.
Types of Sonar
Sonar is broken up into two types: active sonar and passive sonar. Active sonar both sends and receives a signal. It generates a wave of sound that travels outward and is reflected back by an object.
When the receiver picks up this signal, it can analyze the signal to determine the range, bearing, and relative motion of the object.
Passive systems work differently in that they don’t send out a signal. Rather, they listen for noise produced by a target. The specific noises produced can be analyzed to reveal what their characteristics are.
Robert William Boyle
Seeing that the technology of sound detection had a long way to go, Robert William Boyle, a Canadian physicist, tackled the project along with physicist Albert Wood in 1916.
The project was very hush-hush, so much so that the British Admiralty lied directly to the public in an interview with the Oxford English Dictionary about the project, claiming that the project acronym ASDIC was short for Allied Submarine Detection Investigation.
In reality, the project was actually called the Anti-Submarine Division and was a direct response to the need to detect submarines more effectively following the devastating military prowess of the German U-boat.
Boyle’s work for the ASD relied on the use of quartz piezoelectric crystals, which were capable of emitting ultrasound that would reflect back where it hit a target object. This principle was discovered by Paul Langevin, who invented his own sonar device in 1915.
Although Langevin’s invention came too late to help with the threat of U-boats in World War I, his design still proved instrumental in the creation of future sonar apparatuses.
His work on piezoelectric crystals was used by Boyle to create the very first practical underwater detection system. Before the invention of ASIC sonar technology, sonars were entirely passive, only capable of listening for target objects instead of actively sending out a signal to detect their range and bearing.
The HMS Antrim was christened with this new apparatus in 1920 and became the first ship to use a functional, active sonar system.
Sonar and Military History
Although the technology had been around for some time, the use of ASDIC sonar technology would prove to be a bit clumsy during the opening conflicts of World War II.
The sonar could effectively target submarines and were more aware of their approach, but the difficulty lay in the use of depth charges.
In order to destroy a submarine, the attacking ship needed to pass directly overhead before it could fire a depth charge.
Due to the design of the sonar technology at the time, ship captains would lose sonar contact with the submarine moments before firing, enabling the submarine to take evasive action before being hit.
Over time, more advanced strategies for effectively cutting off a submarine’s escape method were created to address the threat.
American Involvement in Sonar Technology
In 1917, J. Warren Horton served the government as an expert in technical engineering. He applied the formative science of electronics to the concept of detecting underwater signals, creating a primitive hydrophone that could pick up sound.
During the first World War, he was sent to England, overseeing the installation of bottom-mounted hydrophones in the Irish Sea. These mounts were crucial for detecting incoming vessels.
Horton would also be a crucial ally in World War II as well, developing systems that were capable of detecting enemy missiles, including mines and torpedoes.
A decade later, other American engineers began developing their own version of this technology, which was dubbed sonar (sound, navigation, and ranging) in reference to the sister technology of radar.
This technology remained largely unmodified until 1945 when advancements in the technology made the apparatus more efficient.
How Sonar Is Used
Sonar was originally considered to detect icebergs and hostile submarines, but it also has a plethora of other uses. In the military, sonar is used in many different systems that are capable of detecting, identifying, and determining the relative position of a submarine.
The technology is also used in homing torpedoes, mines, and for mine detection.
Several nonmilitary uses for sonar are prevalent as well, including finding fish, depth sounding, and mapping the surface of the ocean floor. Doppler navigation and acoustic locating are both tools used by divers.
The principle behind sonar has been known for centuries, but it wasn’t until tragedy struck that the need for an apparatus to detect underwater objects became apparent.
Two major concerns, the risk of iceberg collisions and the threat of the U-boat, contributed to the development of passive sonar systems that were able to detect objects at range underwater.
In primitive sonar systems, the bearing of the object in question wasn’t always clear, prompting the need for a way of determining the relative position of the object in the water.
It was not until piezoelectric quartz crystals were considered that an active sonar system was developed, and active sonar apparatuses like those developed by Boyle could send out a signal and analyze the ‘ping’ from an object to determine its range, bearing, and relative motion to the apparatus.
Over the years, sonar technology has become much more sophisticated and very useful for detection, ranging, and mapping of the ocean floor.