Finding people lost at sea, especially beneath the surface, relies on specialized techniques because standard location systems like GPS don't work in water.
Key Search Methods at Sea
When searching for objects or people underwater, rescuers cannot depend on traditional methods used on land or in the air. This is due to the fundamental properties of water.
Why GPS Doesn't Work Underwater
- Water Density: The density of water is significantly higher than air.
- Electromagnetic Waves: GPS systems use electromagnetic waves to determine location.
- Signal Blockage: The high density of water effectively blocks these electromagnetic waves, preventing GPS signals from penetrating deeply enough to be useful underwater.
Relying on Sonar
Because electromagnetic waves are blocked, rescuers must turn to other methods. Rescuers need to rely on sonar, which uses sound waves.
- How Sonar Works: Sonar (Sound Navigation And Ranging) systems emit sound pulses into the water.
- Detecting Objects: When these sound waves hit an object (like a submerged person or debris), they bounce back as echoes.
- Mapping the Environment: By analyzing the returning echoes, sonar systems can determine the location, shape, and distance of objects underwater, helping search teams map the seabed or locate targets.
Overview of Search Technologies
| Technology | Principle Used | Works Underwater? | Notes |
|---|---|---|---|
| Sonar | Sound Waves | Yes | Primary tool for underwater search. |
| GPS | Radio Waves | No | Blocked by water density. |
| Visual Search | Light Waves | Limited | Only effective in clear, shallow water. |
In addition to sonar for underwater searches, surface searches often involve:
- Aircraft (planes and helicopters) using visual observation or radar.
- Boats and ships conducting grid searches.
- Monitoring emergency beacons (like EPIRBs) if activated, though these are primarily for surface location.
Ultimately, finding someone lost at sea, particularly below the surface, requires specialized acoustic technology like sonar to overcome the limitations imposed by the marine environment on other forms of wave-based detection.
