Risk of collision
(a) Every vessel shall use all available means appropriate to the prevailing circumstances and conditions to determine if risk of collision exists. If there is any doubt such risk shall be deemed to exist.
Every vessel shall use every available means to find out if the risk of collision exists. If in doubt, assume the worst that it exists. Even slightest of doubt means the risk exist.
(b) Proper use shall be made of radar equipment if fitted and operational, including long-range scanning to obtain early warning of risk of collision and radar plotting or equivalent systematic observation of detected objects.
Use radar to detect objects at long range and watch what are they doing. Think (Determine) if the risk of collision exists.
(c) Assumptions shall not be made on the basis of scanty information, especially scanty radar information.
Do not make assumptions. Radar information may not be COMPLETE.
(d) In determining if risk of collision exists the following considerations shall be among those taken into account:
Some of the factors to consider. Do not end here as there may be more factors.
(I) such risk shall be deemed to exists if the compass bearing of an approaching vessel does not appreciably change;
Relative bearing of the APPROACHING object does not change much. Few degrees +/- means risk exists.
(II) such risk may sometimes exists even when an appreciable bearing change is evident, particularly when approaching a very large vessel or tow or when approaching a vessel at close range.
Sometimes bearing change may be large in numbers but the target size may make it insufficient.