INTERNATIONAL ONLY Your vessel is backing out of a slip in a harbor. Visibility is restricted. Which signal are you required to sound?

Correct Answer: Option D — one prolonged blast only

Rule 34(a) applies to vessels in sight of one another. However, Rule 35(g) governs vessels in restricted visibility. A vessel backing out of a slip is not specifically required to sound a signal unless she is a power-driven vessel underway, which would sound one prolonged blast at intervals.