RE: creases in sails
There is no fool proof way to remove these creases. The dacron acts like sheet metal when it gets creased. The outside of the crease actually stretches and cannot be shrunk back to remove the creases. Reverse folding, or burnishing tools or hair dryers are all ineffective in removing the creases. Taking good care of model yacht sails is something that generally gets little attention, and it is one of the major reasons that folks have to replace their sails more often than the actual wear and tear of sailing on the water would require. So just suffer with the sails as they are, for heavens sake don't go after them with your wife's chothes iron as you'll basically destroy the shape holding capability of the cloth.