When a large amount of Notices to Mariners (NtMs) need to be applied in a certain area, it's unpractical to correct by hand. In this case, the Hydrographic Service offers a block correction. This is a chart fragment already corrected with NtMs. You can glue the block directly onto the publication. Below you can click to the blocks.

Do you see uncharted dangers, changes or errors in nautical charts? E-mail to