V) Precautions in Navigating in Poor Visibility

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What is restricted visibility ?

Restricted visibility conditions mean those in which the visibility is Three Nautical Miles or less, or is not more than that designated separately by the Master. Conduct of vessel’s navigation in restricted visibility is covered in COLREG Rule 19.

Action of the OOW in restricted visibility conditions
The officer of the watch shall take the following actions under restricted visibility conditions or if such conditions are expected:
• Inform Master, report existing conditions
• Intensify watch of surrounding conditions, e.g. by posting additional lookout(s)
• Comply with latest International Regulations for Preventing Collision at Sea
• Inform engine room and sound appropriate fog signals.
• Take other necessary action mentioned in the “Navigation in Restricted Visibility Checklist"

Master's action under restricted visibility conditions
When receiving the report from OOW, that restricted visibility conditions are present or expected, the Master shall confirm the navigation situation and if necessary, shall take the command of the ship.

Master shall take appropriate measures as needed such as posting additional Lookout(s), Reduction to safe speed etc.


The check list “Navigation in Restricted Visibility Checklist" shall be used and recorded.




Below is the example of precautions made by Hongkong Vessel Traffic Center in Navigating in Hongkong Waters during Restricted Visibility



Safe Navigation in Poor Visibility

Masters, coxswains and persons-in-charge of vessels are requested to strictly comply with the International Regulations for Preventing Collisions at Sea, 1972 when navigating within Hong Kong waters, especially in poor visibility.


Receive Information

When the visibility in Hong Kong waters is less than two nautical miles, the Vessel Traffic Centre (call-sign "MARDEP") will broadcast visibility reports on V.H.F.'-.J @IJJG!/, channels 12) 14 and 67. These shall be broadcasted on each hour until such time the visibility has improved to more than two nautical miles.








Report Accident

In the event of an accident, it should be reported  immediately to the Vessel Traffic Centre, either on V.H.F. (channel 12, 14, 67) or by telephone (No. 2233 7801 or 2233 7808).






Appropriate Actions to Avoid Collision

  • o Be positive, made in ample time with good seamanship.
  • o Any alteration of course and/ or speed shall be large enough to be readily apparent to other vessel.
  • o Avoid close-quarters situation.








Appropriate Actions in Fog, Restricted Visibility
o Exercise extreme caution.
o Use and listen to sound signals.
o Conduct proper radar observation.
o The Speed Restriction Exemption Permit issued by Marine Department would be voided when the visibility is below one nautical mile.
o Anchor at appropriate location or defer sailing until visibility improves.






Proper Lookout
o By sight and hearing as well - as by all available means
  including radar.







 Safe Speed

o So that vessels can take proper and effective action to avoid collision.
o Circumstantial factors and operational characteristics of radar should be taken into account.









Safe Distance

Pass other vessels at a safe distance.