1. What Is Magnetic Variation?

Magnetic variation (also called magnetic declination) is the angle between magnetic north and true north. This difference is crucial for navigation as it affects compass readings and course plotting on ECDIS systems.

2. How Does The Calculator Work?

The calculator uses the fundamental navigation formula:

Where:

• \( Magnetic Heading \) — Direction measured by magnetic compass relative to magnetic north
• \( True Heading \) — Direction relative to true north (geographic north pole)
• \( Variation \) — Angular difference between magnetic and true north

Explanation: Positive variation indicates east variation (magnetic north east of true north), negative variation indicates west variation (magnetic north west of true north).

3. Importance Of Variation Calculation

Details: Accurate variation calculation is essential for safe navigation, proper course plotting on ECDIS, converting between magnetic and true bearings, and ensuring vessel position accuracy.

4. Using The Calculator

Tips: Enter magnetic heading and true heading in degrees (0-360). The calculator will compute the variation and normalize it to the range of -180° to +180° for practical navigation use.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between variation and deviation?
A: Variation is the difference between magnetic and true north, while deviation is the error caused by magnetic influences on the vessel itself.

Q2: How often does magnetic variation change?
A: Variation changes slowly over time and varies by geographic location. Navigation charts and ECDIS systems provide updated variation data.

Q3: Why is variation important for ECDIS?
A: ECDIS displays true positions, but vessels often navigate using magnetic compasses. Proper variation calculation ensures accurate course plotting and position reporting.

Q4: What is a typical range for magnetic variation?
A: Variation can range from 0° to 30° or more depending on location. Some areas like the North Atlantic have significant variation.

Q5: How do I apply variation in navigation calculations?
A: Use the mnemonic "True Virgins Make Dull Companions" - True heading + Variation = Magnetic heading + Deviation = Compass heading.