Restricted Visibility: What the OOW Must Do

Restricted visibility is one of the most frequently examined topics in MCA oral exams for deck officers at every level. Examiners ask about it because it represents a situation where seamanship, regulation knowledge, situational awareness and decision-making all come together under genuine time pressure. A candidate who gives a strong restricted visibility answer demonstrates real watchkeeping competence.

Why Restricted Visibility Is a Major Oral Exam Topic

Restricted visibility — whether caused by fog, rain, snow, dust or smoke — significantly increases the risk of collision. The regulatory framework governing vessel conduct in restricted visibility is clear, but applying it correctly in a real situation requires more than memorising rule text. Examiners probe whether candidates can demonstrate the judgment and priorities of an experienced officer.

Immediate Priorities

When visibility deteriorates or you navigate into an area of restricted visibility, your immediate priorities are to assess the situation quickly and take action before conditions become critical. Do not wait until visibility has deteriorated severely. The earlier you identify the change in conditions, the more options you have.

Key immediate actions include: reducing to a safe speed, posting an additional lookout, switching to manual steering if appropriate, notifying the Master, posting a listening watch on the VHF, and ensuring all lights are properly displayed.

Safe Speed

Safe speed in restricted visibility is not a fixed figure. It is the speed at which the vessel can take proper and effective action to avoid collision and be stopped within an appropriate distance. Factors include the prevailing visibility, the density of traffic, the manoeuvrability of the vessel, the limitations of radar equipment, and whether radar is being used.

Lookout

Rule 5 requires a proper lookout at all times by sight and hearing. In restricted visibility, this means posting a dedicated bow lookout — not relying on the officer of the watch alone. The lookout must have no other duties that would distract them from watching and listening. A listening watch for sound signals is particularly important when radar range is reduced.

Radar and ARPA Use

In restricted visibility, radar becomes your primary collision avoidance tool. Ensure radar is properly set up and adjusted for the conditions. Use ARPA to track targets and assess closest point of approach (CPA) and time to CPA (TCPA). Plot contacts systematically — do not rely on brief observations. Radar does not remove the obligation to sound fog signals or to keep a proper lookout.

Sound Signals

In restricted visibility, the appropriate fog signal for a power-driven vessel making way is one prolonged blast at intervals of not more than two minutes. Vessels not under command, vessels restricted in their ability to manoeuvre, and vessels at anchor use different signals. Ensure you can describe the correct signal for your vessel and understand what signals from other vessels indicate.

Navigation Lights

Navigation lights must be displayed in restricted visibility regardless of the time of day. Ensure all lights are functioning correctly and are displayed in accordance with the applicable rules for your vessel type.

Calling the Master

The Master should be called whenever the vessel enters restricted visibility or when visibility deteriorates significantly. This is not a sign of weakness — it is a professional requirement and reflects good seamanship. Stand orders and night orders should specify the conditions under which the Master is to be called, and restricted visibility is almost universally included.

Common Candidate Mistakes in Restricted Visibility Answers

• Not mentioning calling the Master
• Describing safe speed as a specific fixed value rather than a contextual assessment
• Omitting sound signals entirely
• Not mentioning posting a dedicated bow lookout
• Focusing entirely on radar without mentioning other obligations

How to Practise Restricted Visibility Scenarios

Restricted visibility questions are best practised through scenarios — not just by reading the rules. Use oral practice sessions to simulate a developing situation: you are on watch, visibility is three miles and deteriorating, you have a radar contact at eight miles on a slightly converging bearing. Work through your response aloud, in order, as if it were real.