What do three short blasts signify?

Three short blasts on a vessel's horn or whistle signify "I am operating astern propulsion." This communication is critical in maritime navigation, serving to inform other boaters of the specific movement and intentions of a vessel. When a boat's operator sounds three short blasts, it explicitly conveys to nearby vessels that they are about to move in reverse. This warning is particularly important in busy waterways where boaters need to be aware of each other's actions to prevent collisions and ensure safe maneuvering.

The operation of astern propulsion can involve various scenarios, such as maneuvering out of a slip or avoiding an obstacle. By clearly signaling this intention, the operator helps maintain safety and navigate effectively in marine environments. Understanding these sound signals is vital for all boat operators to ensure proper communication and prevent misunderstandings on the water.