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:
(a) By all vessels:
(i) the state of visibility;
(ii) the traffic density including concentrations of fishing vessels or any other vessels;
(iii) the manoeuvrability of the vessel with special reference to stopping distance and turning ability in the prevailing conditions;
(iv) at night the presence of background light such as from shore lights or from back-scatter of her own lights;
(v) the state of wind, sea and current, and the proximity of navigational hazards;
(vi) the draught in relation to the available depth of water.
(b) Additionally, by vessels with operational radar:
(i) the characteristics, efficiency and limitations of the radar equipment;
(ii) any constraints imposed by the radar range scale in use;
(iii) the effect on radar detection of the sea state, weather and other sources of interference;
(iv) the possibility that small vessels, ice and other floating objects may not be detected by radar at an adequate range;
(v) the number, location and movement of vessels detected by radar;
(vi) 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.
This Rule is another one of the important Rules. Paragraphs (a) and (b) and their sub-paragraphs are self-explanatory. However, the rule needs some further explanation.
Every vessel: This includes vessels constrained by their draught (CBD) or restricted in their ability to manoeuvre (RAM), which may not be justified in maintaining a high speed when other vessels are in close proximity, because of their limited manoeuvrability.
Safe Speed: This is intended to be a used in a relative sense. If a ship is involved in a collision, it does not necessarily follow that she was going too fast. In clear visibility, collisions can generally be attributed to a bad lookout or to wrong decisions and actions subsequent to detection, rather than to a high speed.
At all times: A relatively high speed might be accepted as being initially safe for a vessel using radar in Restricted Visibility in open waters, provided prompt action is taken to bring the speed down, when radar information shows this to be necessary. Remember, as OOW, the engines are at your disposal and you do not need to call the Master first. In order to maintain a safe speed “at all times”, a continuous appraisal of changes in circumstances and conditions should be made and any necessary alteration of speed must be instantly put into effect.
Proper and Effective Action: A vessel may be unable to take proper and effective action due to the speed being too high, or in some circumstances, too low. At high speed stopping distance may be an issue and at low speed deviation from the course steered.