COLREGS Rule 7 — Risk of Collision

Rule Text

What it means on the water

• →Use ALL available means — bearing compass, radar range and bearing, AIS, binoculars.
• →Constant compass bearing to an approaching vessel = risk of collision (classic CPA = 0).
• →If in doubt, risk of collision must be assumed to exist.
• →Scanty information (incomplete radar plot) cannot support an assumption of no risk.
• →Even an appreciable bearing change does not guarantee safety: a large vessel or tow at close range may still pose risk.

Common exam mistakes

• ✗Thinking a slight bearing change means no risk — Rule 7 says risk may still exist at close range.
• ✗Assuming risk is absent just because radar is not showing a collision course — you must actually plot and analyze.
• ✗Missing the 'if in doubt, risk shall be deemed to exist' standard — this is a mandatory presumption.

USCG exam questions — Rule 7

These questions are drawn from the same pool used in real USCG licensing exams. Correct answers and explanations are shown.

1. 1. Under Rule 7, risk of collision shall be deemed to exist when:

   • A.The compass bearing to another vessel decreases below 30 degrees on the bow
   • B.The compass bearing to an approaching vessel does not appreciably change✓
   • C.Any vessel is within 2 nautical miles and closing
   • D.Two vessels are on reciprocal courses within 5 nautical miles of each other

   Why: Rule 7(d) states that risk of collision shall be deemed to exist if the compass bearing of an approaching vessel does not appreciably change. A steady bearing with decreasing range is the classic CPA-zero scenario. The 2-mile or angle thresholds in other options are not part of the rule.

2. 2. Rule 7 cautions that scanty radar observations shall be:

   • A.Used only as a supplement to visual bearings
   • B.Not relied upon without corroborating visual observations
   • C.Plotted before any conclusions are drawn✓
   • D.Reported immediately to the master

   Why: Rule 7(c) states that if there is any doubt, risk of collision shall be deemed to exist, and that scanty radar observations shall not be relied upon — they must be plotted or otherwise subjected to systematic observation. A single bearing is insufficient; a series must be taken to establish a trend.

3. 3. Under Rule 7, risk of collision shall be deemed to exist if:

   • A.The compass bearing of an approaching vessel does not appreciably change✓
   • B.The other vessel is proceeding at a speed greater than your own
   • C.The other vessel is larger in tonnage than your vessel
   • D.The distance between vessels is less than one nautical mile

   Why: Rule 7(d) states that risk of collision shall be deemed to exist if the compass bearing of an approaching vessel does not appreciably change. A steady bearing combined with decreasing range is the classic indicator of a collision course.

4. 4. Rule 7 states that assumptions shall not be made on the basis of:

   • A.Scanty information, especially scanty radar information✓
   • B.Failure to obtain a VHF response from another vessel
   • C.The absence of a lookout on the other vessel
   • D.An inability to identify the other vessel's flag state

   Why: Rule 7(c) explicitly states that assumptions shall not be made on the basis of scanty information, especially scanty radar information. (The separate maxim that "if there is any doubt such risk shall be deemed to exist" belongs to Rule 7(a), not 7(c).) Either way, mariners must err on the side of caution.

5. 5. Which of the following is an acceptable means of determining if risk of collision exists under Rule 7?

   • A.Using all available means including radar plotting✓
   • B.Calling the other vessel on VHF Channel 16 to request their intentions
   • C.Checking the vessel's AIS destination field
   • D.Comparing vessel speeds as reported in Lloyd's Register

   Why: Rule 7(b) states that proper use shall be made of radar equipment if fitted and operational, including long-range scanning and radar plotting or equivalent systematic observation, to obtain early warning of risk of collision. All available means must be employed.

6. 6. You observe a vessel on your radar at a constant bearing with decreasing range. Under Rule 7, you should:

   • A.Deem that risk of collision exists and take appropriate action✓
   • B.Wait until the vessel is within half a mile before acting
   • C.Sound one prolonged blast to alert the other vessel
   • D.Maintain course and speed since the burdened vessel must give way

   Why: A constant compass bearing with decreasing range is the classic CBDR case, and Rule 7(d)(i) provides that risk of collision shall be deemed to exist if the compass bearing of an approaching vessel does not appreciably change. Rule 7(a) reinforces this by requiring that if there is any doubt, risk shall be deemed to exist, so the prudent action is to assume risk exists and take early, appropriate action.

Frequently asked questions

How do you determine risk of collision under Rule 7?

Rule 7 requires use of all available means — primarily compass bearing observation and radar. If the compass bearing to an approaching vessel is not appreciably changing, risk of collision shall be deemed to exist. If there is any doubt after assessment, risk must also be assumed to exist. You may not make assumptions based on limited information.

Does an appreciable bearing change mean it is safe?

Not necessarily. Rule 7 notes that risk may still exist even when bearing is changing, especially when approaching a very large vessel, a tow, or any vessel at close range. A widening CPA on radar is more definitive than bearing observation alone.

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