Peel the pineapple, remove the eyes, then slice in about ⅜" slices. (You don't have to be super accurate, but you want the slices thicker than ¼" and not quite ½".) As the slices dehydrate, they become thinner.
Core the slices. If you can core the pineapple before you slice it, then that's okay. I find it easier to core each slice with my apple corer.
Stir together the water and sugar in a large pot (I used my Dutch oven) over high heat. (If it doesn't look like this will cover all the pineapple, then add another ½ cup of sugar and one cup of water.)
Bring the sugar water to a rolling boil.
When the water is boiling, carefully add the sliced pineapple and bring the syrup back to a simmer.
Cover and simmer for 50-60 minutes until the fruit is translucent.
While the pineapple is simmering place a wire cooling rack onto a baking sheet. If you are not using a dehydrator, then heat your oven to 200ºF
With a slotted spoon remove the pineapple rings from the syrup and place on the prepared cooling rack to drain. Do not overlap the slices.
If you have a dehydrator, then follow the directions to dry the rings.
Place the pans with the racks of fruit into the oven to dry. In my oven this took 6 hours; but I live in a humid environment, so it may take less time in your oven. Check the fruit occasionally to see if it is done.
Sprinkle slices generously with granulated sugar.
Now try to keep your family from eating them all up before you serve them!