I'm working on a Skerry. Rails are done! Thanks to CLC support, and a few Q&A rounds here.

Now the skeg. I need to mark the bottom of the hull to center the skeg. The hull is covered with epoxy, so -- dumb question -- what do you recommend for temporary marks? Pencils and pens don't work. I don't want to use a permanent marker (even though I will almost certainly be painting the hull).

What can I use to write on the hull, that can be easily removed once the skeg is in place?