What is the DANGER SIGNAL and when should it be used?

The DANGER SIGNAL is specifically defined in the International Regulations for Preventing Collisions at Sea (COLREGs), and it consists of five short blasts on a whistle or horn. This signal is used when a vessel's intentions are uncertain or when there is a potential danger to other vessels. By sounding five short blasts, a vessel communicates to others that its maneuvering is not clear and that caution should be exercised, as it may lead to a dangerous situation.

This signal is particularly important in situations where visibility is poor or when vessels are navigating in close quarters, where misunderstandings could lead to collisions. It serves as an important safety measure to ensure that all vessels are aware of potential hazards and can take the necessary precautions.

In contrast, the other options represent different sound signals used for varied purposes under the regulations. While they may also be important, they do not fulfill the same role as the DANGER SIGNAL, which is specifically about indicating uncertainty in intentions.