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
  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.