RYA Day Skipper Navigation and Chartwork

Question 1

On an Admiralty chart, what do the letters 'M' and 'S' indicate when describing the seabed?

Accepted Answer

Mud and Sand

Answer

On Admiralty charts, 'M' denotes Mud and 'S' denotes Sand as bottom characteristics. These abbreviations help mariners understand the nature of the seabed for anchoring.

Question 2

What is the difference between 'variation' and 'deviation' in compass navigation?

Accepted Answer

Variation is the difference between true and magnetic north; deviation is the error caused by the vessel's own magnetic field

Answer

Variation is the angular difference between true north and magnetic north at a given location (caused by the Earth's magnetic field). Deviation is an additional error caused by magnetic influences aboard the vessel.

Question 3

When plotting a position on a chart using latitude and longitude, which coordinate is read first?

Accepted Answer

Latitude

Answer

By convention, latitude (measured in degrees north or south of the equator) is always stated first, followed by longitude (measured east or west of the prime meridian).

Question 4

What is a 'cocked hat' in chartwork?

Accepted Answer

The triangle formed when three position lines do not intersect at a single point

Answer

A cocked hat is the small triangle formed on a chart when three position lines (from bearings or other observations) do not meet at a single point, due to small errors. Your position is assumed to be within this triangle.

Question 5

How is distance typically measured on a nautical chart?

Accepted Answer

Using the latitude scale at the side of the chart, where one minute of latitude equals one nautical mile

Answer

On a nautical chart, one minute of latitude equals one nautical mile. Distance is measured using dividers against the latitude scale on the sides of the chart, at the same latitude as the measurement.

RYA Day Skipper Practice Test

RYA Day Skipper Practice Test

RYA Day Skipper Navigation and Chartwork