Restricted Visibility Signals Practice Questions

1. A power-driven vessel is underway in fog but has stopped and is not making way. What signal does she sound under Rule 35(b)?

• A.One prolonged blast every 2 minutes
• B.Two prolonged blasts in succession every 2 minutes✓
• C.One prolonged blast followed by two short blasts every 2 minutes
• D.Three short blasts every 2 minutes

Why: Rule 35(b) prescribes two prolonged blasts in succession, with an interval of about 2 seconds between them, repeated at intervals not exceeding 2 minutes. This distinguishes a stopped (not making way) power-driven vessel from one making way (one prolonged blast, Rule 35(a)).

2. You hear one prolonged blast followed by three short blasts in fog. What type of vessel is most likely producing this signal?

• A.A vessel at anchor
• B.A vessel being towed, or the last vessel in a tow if manned✓
• C.A pilot vessel on duty
• D.A power-driven vessel making way

Why: Rule 35(d) assigns one prolonged blast followed by three short blasts to the vessel being towed, or if more than one vessel is being towed, the last vessel in the tow if manned. This allows other vessels to determine the length of the tow ahead. It is sounded after the towing vessel's signal if practicable.

3. A pilot vessel on duty in restricted visibility may sound which additional identity signal on the whistle?

• A.Three short blasts
• B.Four short blasts✓
• C.Two prolonged blasts
• D.One prolonged followed by one short blast

Why: Rule 35(i) states that a pilot vessel on pilotage duty may, in addition to the prescribed fog signals for power-driven vessels or sailing vessels, sound an identity signal of four short blasts. This supplement lets other mariners identify the vessel as a pilot boat even in zero visibility.

4. A vessel restricted in ability to maneuver (RAM) is underway in restricted visibility. What fog signal must she sound?

• A.One prolonged blast every 2 minutes
• B.Two prolonged blasts every 2 minutes
• C.One prolonged followed by two short blasts every 2 minutes✓
• D.One prolonged followed by three short blasts every 2 minutes

Why: Under Rule 35(c), a RAM vessel underway sounds one prolonged blast followed by two short blasts at intervals not exceeding 2 minutes. This signal is shared with NUC, sailing, fishing, constrained-by-draft, and towing vessels. A RAM vessel anchored uses the standard anchor bell of Rule 35(g).

5. A 120-meter vessel is at anchor in restricted visibility. How must she supplement the forward bell signal?

• A.She sounds one prolonged blast after the bell
• B.She sounds three short blasts after the bell
• C.She strikes a gong rapidly in the after part immediately after ringing the forward bell✓
• D.She sounds a whistle signal in addition to the bell

Why: Rule 35(g) states that for vessels 100 meters or more in length, the bell is rung rapidly for 5 seconds in the forepart of the vessel, and a gong is struck rapidly for 5 seconds in the after part immediately after the bell. This gives anchored vessels in fog a forward and aft audio signal so approaching vessels can determine their aspect.