Rule 7 covering Risk of Collision, which warns that "assumptions shall not be made on the basis of scanty information, especially scanty radar information:"

(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

(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

(c) Assumptions shall not be made on the basis of scanty information, especially scanty radar information.

(d) In determining if risk of collision exists the following considerations shall be among those taken into account:

(i) such risk shall be deemed to exist if the compass bearing of an approaching vessel does not appreciably change;

(ii) such risk may sometimes exist even when an appreciable bearing change is evident, particularly when approaching a very large vessel or a tow or when approaching a vessel at close range.

Part A - General (Rules 1-3) & Part B- Steering and Sailing Section 1 - Conduct of vessels in any condition of visibility (Rules 4-10)

Rule 1 states that the rules apply to all vessels on the high seas and connected waters.
Rule 2 covers the responsibility of the master, owner and crew to comply with the rules.
Rule 3 includes definitions of applicable water craft (vessels).
Rule 4 says the section applies in any conditions of visibility.
Rule 5 every vessel shall at all times maintain a proper look-out by sight and hearing.
Rule 6 deals with safe speed.

Rule 7 risk assumptions shall not be made on scanty (radar) information.
Rule 8 covers action to be taken to avoid collision.
Rule 9 vessels proceeding along a narrow channel should keep to starboard.
Rule 10 deals with the behaviour of vessels in or near traffic separation schemes. 

Sections II & III Conduct of Vessels in Sight of one another

Part C - LIGHTS & SHAPES (Rules 20-31)

Part D - SOUND AND LIGHT SIGNALS - DEFINITIONS (Rules 32-37)

Part E - EXEMPTIONS - Rule 38

Part F - Convention compliance verification provisions Rules 39 - 41

Annex I - Positioning and technical details of lights and shapes

Annex II - Additional signals for fishing vessels fishing in close proximity
Annex III - Technical details of sounds signal appliances
Annex IV - Distress signals indicating distress and need of assistance

International Maritime Organization (IMO)

4 Albert Embankment, London SE1 7SR

United Kingdom
+44 (0) 20 7735 7611

LINKS & REFERENCE

http://www.solarnavigator.net/boats/collision_at_sea_regulations_colregs.htm

https://www.bluebird-electric.net/COLREGS_International_Regulations_for_Preventing_Collisions_at_Sea_1972.htm

http://www.solarnavigator.net/boats/collision_at_sea_regulations_colregs.htm

https://www.bluebird-electric.net/COLREGS_International_Regulations_for_Preventing_Collisions_at_Sea_1972.htm