Sailing vessels during periods of reduced visibility should sound which pattern?

• A. Two prolonged and one short
• B. One prolonged and two short
• C. One long
• D. Three short

Answer: (B)

In reduced visibility, ships rely on whistle signals to convey presence and intent so others can avoid a collision. The pattern of one prolonged blast followed by two short blasts is the standard signal used to indicate a vessel is operating in restricted visibility and is communicating its presence and intended caution. The longer blast grabs attention at a distance, while the two short blasts create a distinctive sequence that others recognize as the appropriate warning signal in poor visibility. A single long blast or three short blasts do not carry the same, specific meaning, so they’re not as effective for this situation.