Got one of those transparent waterproof document wallets for Christmas and thought I would copy my paper charts into smaller chunks and keep the relevant set in the wallet for quick reference. Retrieved my charts still in the cardboard postal tube from the boat and took them home to find they have mildew spots all over them, but fortunately not bad enough to make them unreadable. Copied two charts into 8 x A3 sheets each at the same resolution as original with around 30 mm overlap between sheets and numbered them. Using a Portland plotter and divider are these copies good enough for fixing position from GPS or LOP for coastal cruising that I could leave the originals home? What is the best way to store charts on a boat? I keep one of those moisture absorbers in the head and haven't noticed any mould or condensation any where else on the boat. Thanks