Updates to ADMIRALTY services are issued weekly on Thursdays. They are supplied on CD, DVD and over the Internet. Where possible updates should be applied weekly, but where this is not possible (e.g. mid-voyage), updates should be applied at the next opportunity.
ARCS & AVCS discs are cumulative so only the most recent Base and Update discs need to be installed and older disks can be discarded .
Base discs are reissued periodically to prevent the Update disc becoming full. When Base discs are reissued they must be loaded in to the ECDIS in the same way as an update disc. Always retain the most recent Base discs that you have received as they will be needed if you purchase more charts.
