What sound signal does a PDV making way through water in restricted visibility use?

A power-driven vessel (PDV) that is making way through water in restricted visibility is required to use a specific sound signal to indicate its presence to other vessels. The correct sound signal in this scenario is one short blast. This signal serves to inform other vessels that the PDV is underway and is taking active navigation measures to avoid collisions.

The use of this sound signal is established in the International Regulations for Preventing Collisions at Sea (COLREGs), specifically emphasizing the importance of communication between vessels in situations where visual contact may be limited. In restricted visibility, it is crucial for vessels to be aware of one another's positions and intentions, and the one short blast conveys that the vessel is moving forward. Thus, when a PDV is making way, it emits one short blast.

In contrast, other signals serve different purposes. For example, one prolonged blast is used to signal a PDV that is not making way or is about to turn; two short blasts may indicate that a vessel is turning to port; and three prolonged blasts typically signify that a vessel is at anchor. Each of these signals communicates specific intentions or actions, highlighting the importance of sound signals as part of navigational safety in restricted visibility conditions.