Yachtmaster revision module 6 of 20

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Position, Course & Speed

True bearings, courses, latitude, longitude, and the knot.

True bearings and coursesStandard navigational terms

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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Lesson summaries

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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...

  • Latitude = N/S of Equator (0°–90°)
  • Longitude = E/W of Greenwich (0°–180°)
Read the full lesson: Latitude and Longitude

True Bearings and Courses

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°)
Read the full lesson: True Bearings and Courses

Speed, Distance, and Time

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
Read the full lesson: Speed, Distance, and Time

Measuring Bearings on the Chart

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
Read the full lesson: Measuring Bearings on the Chart

Measuring Distance on the Chart

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
  • 1 minute of latitude = 1 nautical mile
Read the full lesson: Measuring Distance on the Chart

GNSS Limitations and Cross-Checks

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
Read the full lesson: GNSS Limitations and Cross-Checks

Radar and AIS for Position Confirmation

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
Read the full lesson: Radar and AIS for Position Confirmation

Yachtmaster Offshore Standard

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.
  • Name the margin that makes the plan defensible.
Read the full lesson: Yachtmaster Offshore Standard

Advanced Scenario Check

Decision pressure: A delayed decision will reduce sea room, so the position problem must change the plan immediately.

  • Apply True bearings and courses to a changed real-world situation.
  • Separate fact, estimate, and assumption.
Read the full lesson: Advanced Scenario Check

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