What is the length of a prolonged blast sound signal?

A prolonged blast sound signal is defined as lasting for a duration of 4 to 6 seconds. This length is significant in the context of maritime communication, specifically for signaling intentions or providing warnings to other vessels in close proximity, especially in conditions of reduced visibility or heavy traffic. The duration helps ensure that the signal is noticed and understood by nearby boaters, promoting safety on the water.

Other options do not meet the criteria established for a prolonged blast, which is crucial for effective communication at sea. A blast lasting shorter than the specified range could be perceived as a different signal, potentially leading to confusion or misinterpretation about a vessel's intentions. Therefore, adhering to the 4 to 6 seconds standard is essential for clarity and safety in maritime navigation.