If a ship sinks, what device is designed to float free of the mother ship and transmit a distress signal?

The device that is specifically designed to float free from the mother ship and transmit a distress signal in the event of a sinking is known as an emergency position indicating radio beacon (EPIRB). This equipment is crucial in marine safety, as it sends out a distress signal that is transmitted to satellites to enable search and rescue operations.

An EPIRB operates automatically when it comes into contact with water, which ensures that it can function effectively even when the ship is in distress and the crew may not have the opportunity to activate it manually. It emits a distress signal that provides vital information about the vessel's location, significantly increasing the chances of a successful rescue.

While other options, such as the specific frequencies used by EPIRBs or bridge-to-bridge communication devices, are relevant in maritime communication, they do not specifically address the design and purpose of a device intended to float free and signal distress when a ship is sinking. The primary function of the emergency position indicating radio beacon is the critical aspect that makes it the correct choice in this scenario.