Sonobuoys have been in use for nearly a century, but the technology behind the underwater tool continues to evolve. An effective but short-lived investigative tool, sonobuoys are vital components to the US military, researchers, and those in the oil and gas industry. Curious to know how it works? Take a look at the following to see how this unique piece of equipment works.

What are sonobuoys?

People have long used buoys or floats to mark locations on the water. A sonobuoy is simply a float that uses sonar technology in the ocean for a number of different reasons. Sonobuoys were originally made to detect enemy submarines during World War I. The US Navy still uses this technology today for many of the same reasons.

In general, there are three different types of sonobuoys: active, passive, and special purpose. All three have a particular purpose and are used for different reasons. Some of the purposes include recording underwater earthquake activity, listening to mammal calls, and investigating parts of the ocean not available to scuba divers.

How do sonobuoys work?

Sonobuoys are generally housed in boats and ejected from aircraft or vessels into the ocean. A float houses a radio transmitter that sits on the surface of the water, while hydrophone sensors are released underwater. A hydrophone sensor is simply an underwater microphone that records sound. The sensors transmit sound information to the radio transmitter, which, in turn, transmits the information to the users.

Active sonobuoys emit sound in the water and record return echoes. Aircraft can use this information to track and trace submarines. A passive sonobuoy, as its name implies, does not emit any sound. Rather, it tracks sound underwater without revealing its own location.

There are also sonobuoys that are not used for military purposes. Special purpose sonobuoys are most often used by search and rescue groups or investigators. These instruments are designed to travel to different depths and collect various types of information, which helps track down crash sites and sinking ships. Some buoys read salinity levels and barometric pressures, while others include GPS tracking equipment. Essentially, however, all sonobuoys use some form of hydrophone sensors to make acoustic readings.

sonobuoys today

These types of underground instruments, which use SONAR technology, have not always been efficient. In fact, most researchers discounted their use at first, finding them quite ineffective. Most of the research came to a temporary halt after World War I.

Today, however, technology has evolved to where sonobuoys are quite effective, taking on a more slender shape. These instruments can travel to greater depths and can transmit signals, via the radio transmitter, over greater distances, allowing aircraft to stay farther from the site. Some devices only transmit information, while others are made to store information until it is retrieved. These instruments have been designed to resist corrosion, underwater storms, and animal interference. Sonobuoys have become plentiful instruments since the day they were created.