Why Restricted Visibility Changes Everything
Restricted visibility is the condition in which the collision regulations are most often broken and casualties most commonly occur. The Master's obligation is not merely to react when fog closes in — it is to anticipate, plan, and make command decisions before visibility degrades. Passage planning for restricted visibility is therefore an extension of the Master's duty of care, embedded in SOLAS V (safe navigation) and the COLREGS, and examined at command level.
The Planning Obligation
A voyage plan is required under SOLAS V/34. For a yacht Master, 'ample time' and 'due regard' mean that restricted visibility must be treated as a foreseeable hazard and addressed in the plan — not improvised. The plan should identify:
- Stretches of passage with elevated fog probability: seasonal patterns, coastal anchorages, river approaches, traffic separation schemes.
- Decision points (waypoints of commitment): positions at which proceeding further commits the vessel to a port approach or narrow channel in potentially reduced visibility, and the point at which turning back or anchoring remains seamanlike.
- Safe anchorages and bolt-holes: identified in advance with depths, holding, and approach bearings — not chosen under pressure with visibility at 200 metres.
- Traffic density and separation schemes: a yacht entering a TSS in restricted visibility faces COLREGS Rule 19 interactions with vessels she cannot see and that cannot see her. The plan must address whether transit timing can avoid peak traffic periods.
- Radar conspicuous marks and clearing bearings: identified in advance so the watchkeeper can navigate by radar alone if needed.
- Speed and stoppage distance: the plan should note that Rule 19(b) requires safe speed — explicitly adjusted for the conditions — and the Master should know the vessel's stopping distances at various speeds.
The Command Decision
Voyage planning for restricted visibility ultimately forces one command-level decision: proceed, wait, or divert. This cannot be left to the officer of the watch. The Master must define in the plan (or in standing orders) the visibility threshold below which:
- Speed is reduced and the Master is called.
- The anchor is let go or a bolt-hole is entered.
- A port approach is abandoned and an alternative sought.
COLREGS Rule 19 applies the moment visibility is restricted — not when it reaches zero. Planning must reflect this.
Radar and Sound Signals
The plan should confirm that radar is operational and set up correctly before departure, that the vessel's sound signalling equipment complies with COLREGS Rule 35, and that all crew know their fog signal duties. On a small yacht the Master should not be simultaneously navigating, plotting, and operating the foghorn.
Record and Briefing
The completed plan, including restricted-visibility contingencies, should be recorded and briefed to all watchkeeping officers before departure.