Indicator net facts for kids
Imagine huge, strong nets made of light steel. These were called indicator nets. During World War I and World War II, navies used them to protect their important bases. They would anchor these nets deep in the sea, hoping to catch enemy submarines, called U-boats. Even if a U-boat got tangled, it often managed to escape before it could be attacked with depth charges.
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What are Indicator Nets?
Indicator nets were like giant underwater fences. They were mainly used by the Royal Navy (the British navy) to stop enemy submarines from sneaking into their waters. These nets were very long, sometimes as much as 100 meters (about 330 feet) each!
How Indicator Nets Worked
These nets were not usually used alone. They were often placed alongside large areas of mines and where warships were patrolling. Sometimes, mines were even attached directly to the nets. This made it much harder for a submarine to survive if it got caught.
When a submarine got tangled in a net, a special marker buoy would float to the surface of the water. This buoy would show that an enemy submarine was below. It was like a big "X marks the spot" for the navy.
Famous Encounters
One of the first times an indicator net helped destroy a U-boat was near Dover, England. On March 4, 1915, a German submarine called the U-8 got caught in a net.
The British also used indicator nets with special fishing boats. These boats were armed with guns and depth charges. If a submarine got caught in their net, the boats would attack it. Many of these boats were used in the Mediterranean Sea. They helped block the Strait of Otranto, a narrow passage.
On May 12, 1917, an Austro-Hungarian submarine called SM U-6 got caught in one of these nets. The captain tried to surface and cut the net free. But the net had tangled its propellers, so it couldn't escape. The crew had to sink their own submarine, but luckily, everyone was rescued.
Indicator Nets Today
After World War I, the British kept working on improving indicator nets. The Americans didn't focus on them as much until 1939, when the British shared their knowledge.
During the attack on Pearl Harbor in 1941, Japanese mini-submarines managed to get into the harbor. They used their small size and special net cutters to get past the existing submarine nets. After this attack, a new, lighter type of indicator net was quickly put in place at Pearl Harbor.
Today, new types of robots are used in the water, like unmanned surface vehicles (boats without people) and unmanned underwater vehicles (underwater drones). Because of these new technologies, indicator nets are being thought about again as a way to defend important areas.
See also
- Anti-submarine indicator loop
