Day Skipper training module 9 of 17

🧭

Compass

Hand-bearing compass, variation, deviation, and compass conversions.

Use of hand-bearing compassApplication of variation
3 outcomes for this module
  • Explain hand-bearing compass, variation, deviation, and compass conversions.
  • Apply Use of hand-bearing compass to a realistic onboard situation.
  • Recall the core check: true North — geographic north (charts are drawn to true north).
Preview the onboard scenario

You are preparing a real trip where your understanding of use of hand-bearing compass shapes the decision. Use this module to explain the cue, the risk, and the next safe action before you move on.

5 lesson sections · 18 quiz questions · 12 flashcards

On narrow screens, scroll sideways to reach every study mode.

Lesson summaries

Use this module hub to choose the right lesson, then open the dedicated lesson page for the complete explanation, worked examples, FAQs, and practice questions.

Three Norths

To understand compass work, you need to know there are three different 'norths'. True North is the geographic North Pole — all charts are aligned to true north. Magnetic North is where a...

  • True North — geographic north (charts are drawn to true north)
  • Magnetic North — where a compass needle naturally points
Read the full lesson: Three Norths

Variation

Variation is the angular difference between True North and Magnetic North. It changes slowly over time and varies by location. On a chart, variation is printed on the compass rose — for e...

  • Variation = difference between True North and Magnetic North
  • Found on the chart compass rose with date and annual change
Read the full lesson: Variation

Deviation

Deviation is the error caused by magnetic influences on YOUR boat — the engine, electronics, metal fittings, and even a mobile phone near the compass can deflect the needle. Unlike variat...

  • Deviation = compass error caused by the boat's own magnetic field
  • Different on every heading (unlike variation, which is constant for an area)
Read the full lesson: Deviation

Converting Between Bearings — CADET and CDMVT

To convert between True, Magnetic, and Compass bearings, you add or subtract Variation and Deviation. The mnemonic CADET tells you whether to add or subtract: Compass + Add + Deviation +...

  • CADET: Compass ADd East for True (Compass → True)
  • Cadbury (C) Dairy (D) Milk (M) Very (V) Tasty (T)
Read the full lesson: Converting Between Bearings — CADET and CDMVT

Using a Hand-Bearing Compass

A hand-bearing compass is a portable compass used to take bearings of objects. Hold it up to your eye, sight on the object through the prism, and read the bearing from the compass card. I...

  • Hand-bearing compass gives magnetic bearings when kept clear of local magnetic influences
  • Hold away from metal and electronics for accuracy
Read the full lesson: Using a Hand-Bearing Compass

Add the complete practice layer

Keep reading the public lesson articles, and add this module's guided flow, quizzes, spaced-repetition flashcards, progress, and mock exams with one payment.

Unlock for £4.99Already paid? Restore access

Authority cluster

Study this topic deliberately

Secure outcome
Keep True, Magnetic and Compass references explicit through every correction.
Common mistake
Applying east or west mechanically without writing the starting and target reference.
Best next practice
Write one conversion per line and reverse it as an independent check.

Related practice and explanations

Use the compass workbenchSee True, Magnetic and Compass relationships move.Practice a course to steerApply compass corrections after the tidal vector.
PreviousInstrumentsNextChartwork