RESTRICTED VISIBILITY NAVIGATION

1. RESTRICTED VISIBILITY NAVIGATION

3. Collision Avoidance In Restricted Visibility

4. Collision Avoidance In Restricted Visibility Visibility may be restricted by heavy rain, snow, blown spray, low cloud, mist and fog, and in some parts of the world blown sand, and smoke. Fog is defined as excess water vapour in the air, reducing visibility to 1 nautical mile or less.

5. Rule 19Conduct of Vessels in Restricted Visibility

7. (a) This Rule applies to vessels not in sight of one another when navigating in or near an area of restricted visibility.

9. (b) Every vessel shall proceed at a safe speed adapted to the prevailing circumstances and conditions of restricted visibility. A power-driven vessel shall have her engines ready for immediate manoeuvre.

10. (c) Every vessel shall have due regard to the prevailing circumstances and conditions of restricted visibility when complying with the Rules of Section I of this Part.

11. The rules of Section 1 apply in any condition of visibility. The particular rules are those appertaining to:5. Lookout, 6. Safe Speed 7. Risk of Collision8. Action to Avoid Collision9. Narrow Channels10. Traffic Separation Schemes.

12. (d) A vessel which detects by radar alone the presence of another vessel shall determine if a close-quarters situation is developing and/or risk of collision exists.

13. If so, she shall take avoiding action in ample time, provided that when such action consists of an alteration of course, so far as possible the following shall be avoided:

14. (i) an alteration of course to port for a vessel forward of the beam, other than for a vessel being overtaken,

16. (ii) an alteration of course towards a vessel abeam or abaft the beam.

18. (e) Except where it has been determined that a risk of collision does not exist, every vessel which hears apparently forward of her beam the fog signal of another vessel, or which cannot avoid a close-quarters situation with another vessel forward of her beam, shall reduce her speed to the minimum at which she can be kept on her course.

19. She shall if necessary take all her way off and in any event navigate with extreme caution until danger of collision is over.

20. Navigation In Restricted Visibility

22. Navigation • It is important that during restricted visibility, that the position of the vessel is known at all times • This is especially because of the lack of any visual references, unless the vessel is within sight of a navigational aid.

23. Navigation • This is also due to the lack of situational awareness that could come about about using the head up display on the radar, and manoeuvring as required by the Collision Regulations to avoid risk of collision.

24. Parallel Indexing • The principal method of monitoring navigation in restricted visibility is the use of parallel indexing

25. 185 T 0.3 nm 0.3 nm 150 T 0.2 nm

26. Parallel Indexing • The Variable Range Marker is first set up on the same distance as is required to safely pass off the radar conspicuous object being used. • In the example it is set up 0.3nm • This is known as the cross index range

27. Parallel Indexing • The Electronic Bearing Line is set up on the same bearing as the course that is required to be made good

28. Parallel Indexing • It is important that the radar conspicuous objects used in parallel indexing are positively identified from the chart or chart plotter and checked on the radar. • If parallel indexing is attempted on a moving object, it will lead you off course and possibly into danger.

29. 185 T 0.3 nm 0.3 nm 150 T 0.2 nm

30. Parallel Indexing • 1. The vessel is steered, so as to bring the radar conspicuous target against the Electronic Bearing Line.

31. Parallel Indexing • If the target crosses and comes inside the Electronic Bearing Line alter to starboard to increase the distance off. • If the target moves further away from the Electronic Bearing Line, alter to port to put it back on.

32. Parallel Indexing • 2. The course is steered to keep the radar target on the line.

33. 185 T 0.3 nm 0.3 nm 150 T 0.2 nm

34. Parallel Indexing • 3. The vessel is now approaching the alteration of course point. • The next course is 150 T, and cross index range 0.3’ .

35. Parallel Indexing • 4. At this stage short of a catastrophic failure, the vessel will be safe, and the parallel indexing for the new course can be set up

36. Parallel Indexing • 5. Set up the new cross index range (0.3 nm) on the Variable Range Marker, and then change the bearing of the Electronic bearing line to the new course (150 T) and rest it against the Variable Range Marker ring

37. Parallel Indexing • 6. When the Electronic Bearing Line on its new bearing of 150 T is about to come clear of the conspicuous object, alter course of the vessel to 150 T

38. Parallel Indexing • 7. As before, steer the course to keep the conspicuous radar object on the Electronic Bearing Line

39. 185 T 0.3 nm 0.3 nm 150 T 0.2 nm

40. Parallel Indexing • 8. Before the radar conspicuous object No.1 disappears astern, have available the new cross index range of Radar Conspicuous Object 2 available (0.2 nm)

41. Parallel Indexing • 9. Set new cross index range on Variable Range Marker, and move Electronic Bearing Marker on bearing against Variable Range Marker ring. • Steer to line as before

42. Parallel Indexing • The use of parallel indexing need not be confined to restricted visibility, but may be used in clear visibility as well.

43. Monitoring Course • An additional method available for monitoring course is to preset routes into the chart plotter. • These waypoints and routes should be preset into the chart plotter. • The routes should then be verified during the periodic training so that there is complete confidence in these routes.

44. Monitoring Course • The routes can then be used and relied upon in case of unexpected restricted visibility, night time navigation, and in transit on training or during an incident.

45. Sound Signals in Restricted Visibility

47. Sound Signals in Restricted Visibility • Rule 35 • In or near an area of restricted visibility, whether by day or night, the signals prescribed in this Rule shall be used as follows:

48. Sound Signals in Restricted Visibility • (a) A power-driven vessel making way through the water shall sound at intervals of not more than 2 minutes one prolonged blast.

49. Sound Signals in Restricted Visibility • (b) A power-driven vessel underway but stopped and making no way through the water shall sound at intervals of not more than 2 minutes two prolonged blasts in succession with an interval of about 2 seconds between them.

50. Sound Signals in Restricted Visibility • (c) A vessel not under command, a vessel restricted in her ability to manoeuvre, a vessel constrained by her draught, a sailing vessel, a vessel engaged in fishing and a vessel engaged in towing or pushing another vessel shall, instead of the signals prescribed in paragraphs (a) or (b) of this Rule,