Every vessel shall at all times proceed at a safe speed so that she can take proper and effective action to avoid collision and be stopped within a distance appropriate to the prevailing circumstances and conditions.
In determining a safe speed, the following factors shall be among those taken into account:
(a) By all vessels:
The state of visibility.
The traffic density, including concentrations of fishing vessels or any other vessels.
The manoeuvrability of the vessel, with special reference to stopping distance and turning ability in the prevailing conditions.
At night, the presence of background light, such as from shore lights or from backscatter of her own lights.
The state of wind, sea, and current, and the proximity of navigational hazards.
The draught in relation to the available depth of water.
(b) Additionally, by vessels with operational radar:
The characteristics, efficiency, and limitations of the radar equipment.
Any constraints imposed by the radar range scale in use.
The effect on radar detection of the sea state, weather, and other sources of interference.
The possibility that small vessels, ice, and other floating objects may not be detected by radar at an adequate range.
The number, location, and movement of vessels detected by radar.
The more exact assessment of the visibility that may be possible when radar is used to determine the range of vessels or other objects in the vicinity.
Under Rule 6, every vessel must proceed at a safe speed at all times, allowing for prompt and effective actions to avoid collisions and to stop within an appropriate distance. Determining a safe speed involves considering specific factors related to visibility, traffic density, maneuverability, environmental conditions, and the proximity of navigational hazards.
For All Vessels: Factors include visibility, traffic density (especially in areas with fishing or other vessel concentrations), maneuverability (e.g., stopping distance and turning ability), nighttime lighting (such as shore or vessel backscatter lights), environmental conditions (wind, sea state, currents), and water depth relative to the vessel’s draft.
For Vessels with Operational Radar: Additional radar-specific factors include radar equipment limitations, potential range restrictions, the impact of weather and sea conditions on radar clarity, the possibility of undetected smaller objects, and radar-aided visibility assessments.
Maintaining a safe speed also implies continual adjustments based on changing conditions. For instance, reduced visibility may require vessels to slow to maneuvering speed, giving crew more time to assess and avoid risks. Similarly, densely trafficked areas necessitate slower speeds to allow for quick course changes.
Practical Importance of Safe Speed: Safe speed is often lower than full speed, as it allows the vessel more reaction time, greater control for stopping, and minimized collision impact if one does occur. Speed adjustments should be made independently, without awaiting permission, as the responsibility for maintaining safe speed rests with the vessel operator. Technological aids like radar, ARPA, ECDIS, and GPS are helpful but have limitations and should not replace vigilant observation and situational awareness.
In summary, Rule 6 mandates that vessels proceed at a speed safe for current and anticipated conditions, balancing vessel control, safety, and effective collision avoidance.
