An Acoustic Release is used for the recovery of valuable underwater sensors and equipment. The release will hold onto the anchor of a buoyant instrument until it is commanded to release it. An acoustic release has the ability to both receive and transmit signals to a surface instrument. It uses battery power and is typically designed to last for 1-2 years. Acoustic releases can be used in all water depths, and are available in a range of sizes to suit almost any application.
Acoustic releases may be pre-programmed to release at a pre-determined time. Alternatively, a shipboard transmitter can be used to communicate with the acoustic release. The release will reply to the transmitter, indicating how far from the ship it is located and that it is still operating. This can help monitor the system and check that the release is still operating. More advanced systems will allow for the communication and receipt of the sensor data by the vessel. When the equipment is ready to be recovered, the transmitter will first locate the release, and will then transmit a special coded signal to command it to release. The acoustic release will let go of the anchor and float to the surface for recovery.