Hello fellow survivors. I would like to provide some useful information I have found concerning the “Magnets, how do they work?” achievement/trophy. I am playing on the Xbox Series X, though this tactic would likely be usable on other platforms as well. I successfully completed the achievement, and while doing so carefully tested a few theories I had about the compasses and gyrocopter. Please note that I never actually held the compass in my hand, and I think that is the only way to mess up the achievement. I was able to drop the compasses directly from my inventory on the beach. I carefully used the left trigger (controls may vary by platform) to arrange them facing in different directions while on the ground, and found that they still display the correct direction no matter which way they are arranged! You can crouch above them and easily tell direction, therefore allowing you to use them and still get the achievement. You can also still pick them up into your inventory and travel to other islands to use them for navigation anywhere, but it is vital to make sure your hand is occupied by any other item when you pick them up (that way the compass goes directly into your inventory and NOT your hand). Just remember when you drop it again to do so from your inventory, be careful not to put it into your hand. Also, the compass on the gyrocopter can be used freely without compromising the achievement either. I repeat, the only way to mess up this achievement is to hold the compass in your hand. Hope this may help someone to navigate more easily while still earning “Magnets, how do they work?”.
Happy navigation, fellow survivors!