In a whistle signal system, what does four short whistle blasts mean?

In a whistle signal system, four short whistle blasts indicate that the rope is free. This signal is essential for communication, especially in situations involving the movement or handling of ropes and equipment. It informs crew members that the line or rope they were managing is no longer under tension, allowing them to proceed with subsequent tasks safely. Understanding this signal is crucial for maintaining safety and coordination during operations, ensuring that everyone involved is aware of the status of the equipment being used.

The other choices do not correspond to the established meanings of whistle signals. For instance, "Need help" and "Emergency move" typically have different signal conventions that alert crew members to specific emergencies or requests for assistance. "Up" generally refers to a command to raise an item or load, which is not what the four short blasts convey.