COLREG Rule 7 — Risk of Collision
Every vessel shall use all available means to determine if risk of collision exists; if in doubt, such risk shall be deemed to exist.
In practice
OOW uses radar plotting (ARPA target tracking) to determine CPA / TCPA continuously. AIS supplements but does not replace radar. Constant compass bearing on a closing target = collision risk per Rule 7.
Regulatory detail & full definition
COLREG Rule 7 — Risk of Collision: '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.' Specific guidance: proper use of radar including long-range scanning, systematic observation of compass bearings, and special caution on a constant compass bearing of an approaching vessel. The rule's burden of proof is one-sided — when in doubt, presume risk exists, and act on the higher-priority rules accordingly.
Authoritative source: COLREG 1972 ↗
Related
Source: COLREG 1972 Rule 7
High confidence
Editorial confidence: how we grade.