We recommend the following instruments for making temporary and permanent mark-ups on Maptech Waterproof charts.
A standard #2 pencil (used lightly) works well. A soft eraser will easily remove any mark-up without scuffing the chart image. Hard erasing may begin to remove the chart image.
Any water soluble pens or markers can be used, and should wipe off easily with water. (Keep in mind that they will also smudge easily when exposed to water.)
To be safe, we recommend testing your marker or pencil on a non-critical area.
Any permanent marker should work. Ultra fine point is a good thickness.