MCA CoC Navigation and Chartwork 2 — Questions and Answers
Question 1: A vessel observes a lighthouse bearing 270°(T) at 2000hrs and 315°(T) at 2030hrs while maintaining a course of 000°(T) at 10 knots. What is the approximate distance off the lighthouse at 2030hrs?
- 3 nautical miles
- 5 nautical miles (Correct answer)
- 7 nautical miles
- 10 nautical miles
Correct answer: 5 nautical miles
Using the running fix technique, the vessel has run 5 nautical miles in 30 minutes at 10 knots. The bow angle changes from 90° to 45° (relative bearings). Applying the doubling the angle on the bow principle or trigonometry, the distance off at the second bearing is equal to the distance run, which is 5 nautical miles.
Question 2: What is the purpose of applying the 'cocked hat' principle when taking a three-bearing fix?
- To confirm the vessel is on the correct heading
- To identify potential systematic errors and estimate the most probable position within the triangle formed (Correct answer)
- To calculate the speed over the ground
- To determine the tidal stream direction
Correct answer: To identify potential systematic errors and estimate the most probable position within the triangle formed
When three position lines do not intersect at a single point, they form a triangle called a 'cocked hat'. The navigator's most probable position lies within or near this triangle. A large cocked hat may indicate systematic error such as compass deviation, while a small one suggests good accuracy.
Question 3: In UK waters, what do the abbreviations 'MHWS' and 'MLWS' stand for on Admiralty charts, and what is their significance for navigation?
- Maximum High Water Springs and Minimum Low Water Springs — extreme recorded values
- Mean High Water Springs and Mean Low Water Springs — the average spring tide levels used for clearance calculations (Correct answer)
- Measured High Water Seasonal and Measured Low Water Seasonal — seasonal averages
- Marked High Water Survey and Marked Low Water Survey — surveyed water levels
Correct answer: Mean High Water Springs and Mean Low Water Springs — the average spring tide levels used for clearance calculations
MHWS (Mean High Water Springs) and MLWS (Mean Low Water Springs) are the average heights of the highest and lowest spring tides respectively. MHWS is used to define the coastline on Admiralty charts, while chart datum (approximately LAT) is used for depth soundings. These values are essential for calculating under-keel clearance and overhead clearance.
Question 4: A vessel's compass heading is 130°(C). The variation is 4°W and the deviation for that heading is 2°E. What is the true heading?
- 128°(T) (Correct answer)
- 132°(T)
- 134°(T)
- 126°(T)
Correct answer: 128°(T)
To convert compass to true: True = Compass + Deviation + Variation (applying W as negative and E as positive). So: 130° + (+2°) + (-4°) = 128°(T). The mnemonic 'Cadbury's Dairy Milk Very Tasty' (Compass → Deviation → Magnetic → Variation → True) helps remember the order, adding easterly and subtracting westerly errors.
Question 5: What is the primary purpose of a passage plan as required by the MCA and SOLAS regulations?
- To calculate fuel consumption for the voyage
- To plan the intended route from berth to berth, identifying hazards, abort points, and contingencies (Correct answer)
- To satisfy port state control inspections only
- To determine crew watch schedules
Correct answer: To plan the intended route from berth to berth, identifying hazards, abort points, and contingencies
Under SOLAS Chapter V Regulation 34 and the MCA's requirements, a passage plan must cover the entire voyage from berth to berth. It must identify navigational hazards, establish safe passing distances, mark abort points and contingency anchorages, note reporting requirements, and account for tidal and weather conditions.
Question 6: When approaching a port in poor visibility, the vessel's ECDIS shows the route crosses an area marked with a magenta 'T' symbol. What does this indicate?
- A traffic separation scheme
- A recommended anchorage area
- An area where VTS (Vessel Traffic Service) reporting is required (Correct answer)
- A submarine cable zone
Correct answer: An area where VTS (Vessel Traffic Service) reporting is required
The magenta 'T' symbol on ECDIS and Admiralty charts indicates a VTS reporting point where vessels are required to report to the Vessel Traffic Service. In poor visibility this is especially important as VTS can provide traffic information and navigational assistance to vessels in the area.
MCA CoC Navigation and Chartwork 2
A vessel observes a lighthouse bearing 270°(T) at 2000hrs and 315°(T) at 2030hrs while maintaining a course of 000°(T) at 10 knots.
What is the approximate distance off the lighthouse at 2030hrs?