Rule 6: Safe speed

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:

• 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 back scatter 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.
• 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.