Seaman's Handbook

PART B. Steering and Sailing Rules : Safe Speed

Every vessel shall at all times proceed at a safe speed so that she can take proper and effective action to avoid a 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 in to account:

(a) By all vessels.
  1. the state of visibility;
  2. the traffic density including concentrations of fishing vessels or any other vessels;
  3. the manoeuvrability of the vessel with special reference to stopping distance and
    turning ability in the prevailing conditions;
  4. at night the presence of background light such as from shore lights or from back
    scatter of her own lights;
  5. the state of wind, sea and current, and the proximity of navigational hazards;
  6. the draught in relation to the available depth of water.
(b) Additionally, by vessels with operational radar:
  1. the characteristics, efficiency and limitations of the radar equipment;
  2. any constraints imposed by the radar range scale in use;
  3. the effect on radar detection of the sea state, weather and other sources of
    interference;
  4. the possibility that small vessels, ice and other large floating objects may not be
    detected by radar at an adequate range;
  5. the number, location and movements of vessels detected by radar;
  6. 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.