Aids to Navigation

Question 1

What is a sector light?

Answer 1

• Sector light is an aid to navigation that displays an arc of different colour lights

Uses

• Boundaries of a navigable waterway
• Change of course of the position
• Shoals/banks
• Area of position e.g. anchorage
• Deep channel
• The white light always marks the safe water/position

Question 2

What are leading lights?

Answer 2

• Two separate structures with marks or lights which are aligned when viewed from the deepest route along a channel or approach

Question 3

What are Lighthouses and beacons?

Answer 3

• Large conspicuous structure. Beacons generally have a lower range than a lighthouse. Beacon can be used instead of a buoy

Uses

• Landfall
• Mark an obstruction
• Provide a reference to take a bearing for a LOP
• Mark entrance to TSS

Question 4

What are floating aids to navigation?

Answer 4

• Buoys or light vessels fitted with RACON (response with putting an image on the radar screen) and AIS AtoNs
• A light vessel may have a white light to signal that it is at anchor
• Virtual AtoNs which are quick to set up but liable to jamming and spoofing

Question 5

What do these characteristics mean on a chart ‘Fl(3)WRG.15s21m15-11M’?

Answer 5

• Characteristics of a light
• Group flash 3
• White, red, green light
• Time period of 15 seconds
• Height of light is 21 metres
• Nominal range is 15 nautical miles (White), 15 to 11 nautical miles (Red) and 11 nautical miles green