Remove as much of the ham from the bone as you can, if necessary. Layer one third of the ham in the bottom of a 6 litre casserole dish. Top with a few pineapple rings and 1/4 of the brown sugar. Repeat the layers ending with pineapple rings on top, but don't sprinkle the last 1/4 of brown sugar.
Pour any juice left in the pineapple can over the ham. Then pour in enough of the ginger ale to fill the dish about half way. Sprinkle the remaining brown sugar over the top.
Cover with aluminium foil and bake for 20 minutes in the preheated oven. Uncover and cook for an additional 20 minutes.