COLREG - Fog Signal Pattern Lookup
Required sound signal pattern in restricted visibility per COLREG Rule 35 by vessel type and operational status.
- Sound signal pattern
- Frequency
Formula, assumptions, limits
COLREG Rule 35 prescribes fog signals by vessel type and status. Signals are sounded at intervals not exceeding 2 minutes (or 1 minute for vessels at anchor or aground). The whistle (or fog horn) is the primary signal device; bells and gongs supplement for anchored and aground vessels.
Sound signal patterns
Vessel/StatusPatternInterval
Power-driven, making wayOne prolonged blastat most 2 min Power-driven, stoppedTwo prolonged blastsat most 2 min Sailing, fishing, towing, RAM, NUCOne prolonged + two shortat most 2 min Vessel being towed (last vessel of tow)One prolonged + three shortat most 2 min Anchored vessel Bell rapidly 5 secat most 1 min Anchored vessel >=100 mBell forward + gong aftat most 1 min Aground vesselThree bell strokes + bell rapidly + three bell strokesat most 1 min Pilot vessel on dutyAbove signals + four short blastsat most 2 min
Prolonged blast = 4 to 6 seconds. Short blast = approximately 1 second.
In short
Required fog signal pattern per COLREG Rule 35.