Build your own water compass:

Create a water compass by filling a non-metallic pie plate or dish with about an inch of water. Place your floatable boat cutout (as shown in the diagram) on the water. Take a magnet and "magnetize" the needle by moving or stroking the magnet along the needle approximately fifteen or more times. Place your magnetic needle on your boat as shown in the diagram and the boat and needle should slowly point north. You have a water compass that points North with the near-frictionless properties of flotation. A good way to prove the magnetic properties of the compass is to have the plate or dish on a board or table that can be steadily picked up and rotated.