I am working on a 18' Buzzards Bay Sloop of my dad's with varnished
decking. The varnish is completly peeling up, and in a few places the
caulking has come out. I am wondering what kind of options I have for
fixing this. I have stripped off most of the varnish and sanded it, so
that part is fine. I am wondering what I should do about the caulking.
What kind of stuff is out there? It should be black.

The existing caulking looks like Sika Flex or something similar, is
that what I should use? Advice would be apreciated.