1. Lesson IV: Magnetic Compass
Nautical Navigation
Lesson IV: Magnetic Compass
Preserving America’s Sailing Legacy * Engaging Sailing’s Next Generation

2. History of Magnetic Compass
No one knows for certain when or where the compass was first invented. But, there is record of use by the ancient explorers and land conquerors over 1000 years ago
First compass was iron ore “loadstone” floating in a bowl of water
Allowed sailors to sail over the horizon without risk of being lost at sea
Before the compass, navigators had to stay along the coastline

3. Direction of Travel Arrow
Parts of a Compass
Direction of Travel Arrow
Magnetic Needle
Orienting Arrow
(“doghouse”)
Rotating Bezel

4. How a Magnetic Compass Works
Consists of a lightweight magnet, or needle, balanced on a nearly frictionless pivot point
The needle always points to the magnetic north pole

5. How a Magnetic Compass Works
Earth’s magnetic field is a closed circulation of electrical currents that flow North or South

6. How a Magnetic Compass Works
Magnetized needle is free to move and align with the Earth’s magnetic field
Basic Law of Magnetism
Opposite Polarities Attract
Same Polarities Repel
So why does the North end of the needle point to the magnetic north pole?
Think of the earth as having an internal bar magnet extending along its axis from Magnetic Pole to Pole

7. What are Some Benefits to a Magnetic Compass?
Self-contained system not reliant on electrical power
Inexpensive and easy to replace
How would you make your own magnetic compass?

8. Exercise Each person will have their own magnetic compass
Orienteering Compass “Hockey Puck” Compass
Using the worksheet, write down the bearings of the objects to the nearest degree