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  • Colreg’s (ROR)
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    • Part A- General
      • Rule 1 – Application
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    • Part B- Steering and Sailing
      • Section 1 (Rule 4 -10)
        • Rule 4 – Application
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        • Rule 6 – Safe Speed
        • Rule 7 – Risk of collision
        • Rule 8 – Action to avoid collision
        • Rule 9 – Narrow Channels
        • Rule 10 – Traffic separation schemes
      • Section 2 (Rule 11 – 18)
        • Rule 11 – Application
        • Rule 12 – Sailing vessels
        • Rule13 – Overtaking
        • Rule 14 – Head on situation
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        • Rule 16 – Action by give-way vessel
        • Rule 17 – Action by stand-on vessel
        • Rule 18 – Responsibilities between vessels
      • Section 3 (Rule 19)
        • Rule 19 – Conduct of vessels in restricted visibility
    • Part C- Lights and Shapes
      • Rule 20 – Application
      • Rule 21- Definitions
      • Rule 22 – Visibility of lights
      • Rule 23 – Power-driven vessels underway
      • Rule 24 – Towing and pushing
      • Rule 25 – Sailing vessels underway and vessels under oars
      • Rule 26 – Fishing vessels
      • Rule 27 – Vessels N.U.C or R.A.M
      • Rule 28 – Vessels constrained by their draught
      • Rule 29 – Pilot vessels
      • Rule 30 – Anchored vessels and vessels aground
      • Rule 31 – Seaplanes
    • Part D- Sound and Light Signals
      • Rule 32 – Definitions
      • Rule 33 – Equipment for sound signals
      • Rule 34 – Manoeuvring and warning signals
      • Rule 35 – Sound signals in restricted visibility
      • Rule 36 : Signals to attract attention
      • Rule 37 – Distress signals
    • Part E- Exemptions (Rule 38)
      • Rule 38 – Exemptions
    • Part F – Verification of compliance with the provisions of the Convention
      • Rule 39 – Definitions
      • Rule 40 – Application
      • Rule 41 – Verification of compliance
    • Annexes
      • Annex 1 – Positioning and technical details of lights and shapes
      • ANNEX II – Additional Signals for Fishing Vessels Fishing in Close Proximity
      • ANNEX III – Technical Details of Sound Signal Appliances
      • ANNEX IV – Distress Signals
  • Glossary
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Twilight

Twilight is the light received from the sun, when the sun is below the horizon, i.e. before the sunrise and after the sunset.Twilight completely ceases in the evening, when the sun is 18° vertically below the horizon. After that, there is total darkness.In the mornings, twilight commences when the sun is 18° vertically below the horizon and ceases at sunrise.The entire period of twilight has 3 stages, Civil, Nautical and Astronomical.Astronomical commences when the sun is 18° below the horizon.Nautical - 12° below the horizon.Civil - 6° below the … [Read more...]

By Cult of Sea Filed Under: Navigation Tagged With: astronomical, civil, lower lat, nautical, navigation, theoretical sunrise, theoretical sunset, twilight

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