Part D — Sound and Light Signals
COLREGS Rule 36 — Signals to Attract Attention
Rule 36 allows a vessel to make any light or sound signal to attract the attention of another vessel, provided the signal cannot be mistaken for a signal prescribed in the Rules and does not impair lookout. A searchlight is explicitly permitted.
Rule Text
If necessary to attract the attention of another vessel, any vessel may make light or sound signals that cannot be mistaken for any signal authorized elsewhere in these Rules, or may direct the beam of her searchlight in the direction of the danger, in such a way as not to embarrass any vessel. Any light used to attract the attention of another vessel shall be such that it cannot be confused with any aid to navigation.
What it means on the water
- →Any light or sound signal may be used to attract attention.
- →The signal must NOT be mistakable for a prescribed Rule signal.
- →A searchlight may be directed at the danger to attract attention.
- →Attention signals must not impair lookout or embarrass any other vessel.
- →The signal must not be confused with an aid to navigation (e.g., buoy lights).
Common exam mistakes
- ✗Thinking there is a specific signal prescribed for 'attracting attention' — Rule 36 allows any signal, provided it cannot be confused.
- ✗Missing the restriction that the signal cannot mimic prescribed signals or aids to navigation.
- ✗Forgetting that a searchlight is explicitly listed as an option.
USCG exam questions — Rule 36
These questions are drawn from the same pool used in real USCG licensing exams. Correct answers and explanations are shown.
1. Under Rule 36, when may a vessel use any light or sound signal to attract the attention of another vessel?
- A.Only in restricted visibility
- B.Only when in imminent danger of collision
- C.At any time, provided the signal cannot be mistaken for any signal authorized by the Rules✓
- D.Only to supplement a distress signal
Why: Rule 36 permits any vessel to use a light or sound signal to attract another vessel's attention at any time, as long as the signal cannot be confused with an authorized signal. It also allows a searchlight to illuminate a nearby vessel but prohibits directing the searchlight so as to embarrass or impede another vessel.
2. Rule 36 permits the use of a searchlight to illuminate another vessel. What restriction applies?
- A.The searchlight must only be used in restricted visibility
- B.The searchlight must not be used in a manner that could embarrass or impede any other vessel✓
- C.The searchlight beam must not exceed 200,000 candela
- D.Only pilot vessels may use a searchlight under Rule 36
Why: Rule 36 expressly states that any light used to attract attention 'shall not be such as could be mistaken for any aid to navigation' and a searchlight must not be used 'in such a manner as to embarrass or impede any other vessel.' Blinding the bridge team of another vessel with a searchlight is specifically prohibited.
Frequently asked questions
- What can you use to attract the attention of another vessel under Rule 36?
- Rule 36 allows any light or sound signal provided it cannot be mistaken for a signal prescribed elsewhere in the Rules and cannot be confused with an aid to navigation. A searchlight may be directed toward the danger. The signal must not impair lookout or embarrass any other vessel.
- Is a flashing searchlight a valid Rule 36 attention signal?
- Yes — directing a searchlight in the direction of the danger is explicitly mentioned in Rule 36. However, the light must not be confused with any aid to navigation (such as a lighthouse with a similar characteristic flash), and it must not impair the lookout of the vessel using it or dazzle any other vessel.
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