When Did Ships Start Using Radar?

Are you wondering when ships started using radar? Learn the history of radar in naval conflict in this helpful article!

When Did Ships Start Using Radar?

Radar is a technology that has been around for over a century and relies on an extremely simple concept, although modern ship radars have an impressive array of functions. But where did this story of radio detection begin, and when did ships start using radar?

The first radar was the XAF, created 8 years after the discovery of the radio reflection phenomenon, and was installed on the USS New York (BB-24) in 1939.

Within a few years of the discovery, radar was the proverbial talk of the town in ranging and detection technology and would become a crucial part of the Pacific Theater in World War II. The rest of this article will discuss the history of radar and the first ships that used the technology.

A Simple Phenomenon

Radar (Radio Detection and Ranging), like many great scientific advancements, was discovered as a result of a simple observation about the natural world.

James Clerk Maxwell, Scottish mathematician, and scientist, set the stage for the discovery of radio waves with his publication of “A Dynamical Theory of the Electromagnetic Field. Here, he demonstrated how magnetic fields travel and predicted the existence of radio waves.

Although Maxwell was ahead of the game with his theory, the creation of radar relied on the observation of one simple phenomenon: radio waves ‘bounce’ back off metallic objects.

Leo C. Young and Dr. Alfred Hoyt Taylor made the first observations of this phenomenon (in the U.S., anyway), noting that as two ships passed each other, there would be interference caused by the pinging of radio waves off the hull of the ship.

German inventor Christian Hülsmeyer is credited with the invention of radar, although the Telemobiloscope, as it was called, wouldn’t be classed as a radar by our modern definitions. It was more like a RAD than a radar since it lacked the ranging ability to pinpoint a ship’s location.

Initially, this technology was used to detect the presence of metallic objects like ships to help prevent collisions, but as tensions began to rise and the military aggression of the Axis powers sparked global conflict, radar would become a crucial part of military technology.

Radar and Military Technology

In America, the idea of detecting and pinpointing targets from a long distance away proved to be an attractive technology to develop for future military conflicts, made even more appealing after the discovery that radio waves from aircraft could also be detected. The development of radar technology came hand in hand with the development of modern sonar.

The need for detection of aircraft and ships was matched by the need to address the threat of the German U-boat. Sonar worked similarly to the principle of radio waves, except that it used sound to ‘bounce’ back from an object to determine its position.

Radar and sonar were vital components leading to the United States’ victory in the Pacific Theater to address Japanese advancements and in the European Theater to mitigate the threat of the German U-boat.

In 1930, the U.S. Naval Research Laboratory began experimenting with radar technology. Their findings led the Committee on Naval Appropriations in the U.S. House of Representatives to offer $100,000 to the Naval Research Laboratory to convert the idea into a functional apparatus.

The XAF Radar

The result of this funding was the XAF, an experimental radar constructed in 1939. The XAF was installed on the battleship New York. The results were impressive, with this experimental apparatus vastly exceeding expectations.

It was capable of detecting aircraft at a range of 100 nautical miles and ships as far away as 15 nautical miles. The XAF also saw use in gunnery practice and offered enough precision to target enemy vessels, even in inclement weather conditions or at night.

Following the incredible successes of radar technology on the New York, the commanding officer immediately recommended that the technology be broadly applied to all aircraft carriers, despite the immense cost of developing the technology.

Believe it or not, the XAF radar antenna lived through the World War II conflict, despite its home ship being sunk in the Battle of Midway.

For several decades, it was displayed in Willard Park near the Washington Navy Yard’s waterfront. Today, it’s housed in the Historical Electronics Museum in Linthicum, Maryland.


The next generation of radar technology was developed by the Radio Corporation of America. The CXAM, as it was called, was whipped up in less than a year and was installed in 1940 on American aircraft carrier Yorktown, battleship California, and four additional cruisers.

The CXAM-1, an improved version of the CXAM, was put into development and placed on numerous ships.

Radar’s Role in World War II

Radar was on its way to being a staple of military ships, and by the time the Japanese attacked Pearl Harbor in 1941, 20 units were already installed on designated ships. These units would soon prove their merit in the Pacific theater to stop the Japanese encroachment on Pacific territory.

The Battle of the Coral Sea

The United States entered World War II as a direct response to the Japanese attack on Pearl Harbor. The Battle of the Coral Sea was a critical victory for the U.S. Navy, and radar played a significant role to that end.

It fundamentally changed the rules of naval conflict forever. Ships no longed had to have visual contact of an enemy vessel to open fire, and the Battle of the Coral sea was the first naval battle in history wherein the ships couldn’t see one another.

The battle was fought over several days after the Japanese occupation of Tulagi, and following a surprise attack by the aforementioned U.S. carrier Yorktown, the Japanese advanced to address the threat of the Allied naval forces gathered at the Coral Sea.

The ships were within 70 nautical miles of one another but couldn’t detect the other fleet through the darkness. Both sides aimed to take out the enemy’s aircraft carrier, but both airstrikes hit other targets. The U.S. sank the Shōhō, a Japanese light carrier, while the Japanese sank a U.S. destroyer and the fleet’s oiler.

2 days later, both sides landed an airstrike on the enemy aircraft carrier, forcing both parties to retreat. Although the Battle of the Coral Sea could be considered a Japanese victory in terms of ships sunk and damage dealt, it was the first time in the broad naval conflict of World War II that a major Japanese advance had been halted.

Final Thoughts

Radar and its sister technology sonar would continue to prove vital to the war effort, and after the war was over, the technology continued to be developed to become more accurate and efficient. It’s astounding to think of the pivotal role radar played in the first ships and certainly exemplifies the old saying that necessity is the mother of invention.

The very first ship radar was installed on, the New York, would become something of a superstar herself in the Pacific Theater, playing a significant role in the Battle of the Coral Sea before meeting her end in the Battle of Midway.

In a way, it’s fitting that the first radar, the XAF, is still preserved as a part of naval and radar technology to this day, a testament to the technology that was discovered precisely when it was needed.