RYA Day Skipper Coastal Navigation & Chart Work 2

Question 1

A depth contour line labelled '10' on an Admiralty chart means:

Accepted Answer

All points on this line have a depth of 10 metres at chart datum

Answer

Depth contours connect points of equal depth referenced to chart datum (CD), which is typically the lowest astronomical tide (LAT).

Question 2

What is meant by 'chart datum' (CD) on UK Admiralty charts?

Accepted Answer

Approximately the level of the Lowest Astronomical Tide (LAT)

Answer

Chart datum on UK Admiralty charts is set at approximately LAT (Lowest Astronomical Tide) — the lowest level the sea is predicted to reach under average meteorological conditions.

Question 3

A mariner takes a single compass bearing of 040°C on a lighthouse. Variation is 4°W and deviation is 0°. The true bearing of the lighthouse FROM the vessel is:

Accepted Answer

036°T

Answer

Compass to True: apply deviation (0) → 040°M; apply variation (W means subtract to go to True) → 040 − 4 = 036°T. The vessel lies on the reciprocal (216°T) from the lighthouse.

Question 4

On a chart, a blue circle with 'PA' next to a depth sounding means:

Accepted Answer

Position Approximate — the sounding position is not precise

Answer

PA stands for Position Approximate, indicating that the sounding or feature has been placed on the chart with limited positional accuracy.

Question 5

What does 'set' mean in the context of tidal stream?

Accepted Answer

The direction toward which the tidal stream flows, expressed as a true bearing

Answer

Set is the direction the tidal stream is flowing toward (e.g., 090° set means the stream is flowing eastward). Rate is the speed of that stream in knots.

RYA Day Skipper Practice Test

RYA Day Skipper Practice Test

RYA Day Skipper Coastal Navigation & Chart Work 2