True bearings, courses, latitude, longitude, and the knot.
True bearings and coursesStandard navigational termsLatitude and longitudeThe knot
9 guided lessons · 20 practice questions · 18 flashcards
3 outcomes · self-guided revision
Explain true bearings, courses, latitude, longitude, and the knot.
Apply True bearings and courses to a realistic onboard situation.
Recall the core check: latitude = N/S of Equator (0°–90°).
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Latitude and Longitude
Position on the Earth's surface is defined using latitude and longitude. Latitude measures north or south of the Equator (0° to 90°N or S). Longitude measures east or west of the Prime Me...
A true bearing is measured clockwise from True North (0°/360°) through East (090°), South (180°), and West (270°). All chart work is done in true bearings initially — compass corrections...
True bearings: measured clockwise from True North
Always written as three figures (e.g., 005°, 090°, 180°)
Speed at sea is measured in knots — one knot equals one nautical mile per hour. Distance is measured in nautical miles (M or nm). One nautical mile = 1,852 metres = 1 minute of latitude.
1 knot = 1 nautical mile per hour
1 nautical mile = 1,852 metres = 1 minute of latitude
To measure a bearing on the chart, use a parallel ruler (or Breton plotter). Align the ruler along the line whose bearing you want to measure, then 'walk' it across to the nearest compass...
Use parallel rulers or plotters to transfer bearings
Read from the outer (True) ring of the compass rose
Distance is measured using dividers on the latitude scale at the side of the chart. Set the dividers to the distance you want to measure on the chart, then transfer them to the latitude s...
ALWAYS use the LATITUDE scale (side of chart) for distance
GPS (and the broader term GNSS, which includes Galileo, GLONASS, and BeiDou) provides position accuracy typically within 5–15 metres under good conditions. However, this accuracy depends...
GPS accuracy depends on satellite geometry (DOP), atmosphere, and environment
HDOP < 2 is good; HDOP > 4 means degraded accuracy
Marine radar transmits microwave pulses and measures the time for echoes to return, giving range and bearing to targets. Radar range is generally more accurate than radar bearing — range...
Radar range is more accurate than radar bearing
A fix from two or more radar ranges is reliable — use charted features
Position, Course & Speed at Yachtmaster level is not just recall. The answer has to show command judgement, evidence quality, margin, and a fallback if the first plan stops being safe.
State the evidence you trust and the evidence you distrust.
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