A magnetic compass can, sometimes, lose its ability to track the Earth's magnetic North. One of the most common causes of this is that the compass might have spent too much time close to magnetic sources, don’t worry, though – there’s a very easy way to fix this! But first, a little bit of history:
Compasses throughout history
A ship's compass was one of the most important items in the early days of seafaring. The compass was frequently stored within and attached to a box via a gimbal so that it was always level and the compass needle could easily settle to magnetic North. "Binnacles” was the name given to more modern gimbals.
However, most people are unaware that there was another item just as important, if not more so, than the ship's compass. It was a "Lodestone," usually a piece of strong magnetite that was used to re-magnetize the compass needle. This was necessary because early compasses would lose their magnetic North tracking ability much faster than the modern-day navigating devices we’re used to. A small piece of iron could also be magnetized with a lodestone and be used as a makeshift compass if the ship's compass was either lost, stolen, or damaged.
‘How does any of this apply to my compass?’ you might ask. A neodymium magnet (also called a rare-earth magnet) can be used as a modern substitute for a lodestone, and any magnetic compass needle can be remagnetized at the magnet's south-seeking pole to track and settle to magnetic North not only faster, but with higher accuracy.
Remagnetizing your Sailor’s Compass
The south end of a neodymium magnet can be found by holding one end of the magnet an inch or so from the compass’ side. You've found the "South" end of the magnet if the North end of the compass needle is attracted to that end. You've found the "North" end of the magnet if the needle's South end is attracted to it. When it comes to things magnetic, remember that "opposites attract." Make sure to mark the South end of the magnet to keep track which side is which.
Tape the south end of the magnet to the side of the compass body with masking tape and leave it for at least an hour, up to a day. Even a few minutes will re-magnetize your compass needle in most cases, but some people prefer to leave the magnet tapped to the compass for as long as a few days. If you tape the North end of the magnet to the compass by accident, the compass needle's "South" end will now point North. There's no need to be concerned. Simply reverse the magnet and tape the south end to the compass to change the magnetic polarity back to where it should be.
After following these steps, your Sailor’s Compass should be in perfect working order! We’d love to hear how things went for those of you that followed these instructions, your feedback is always appreciated!