Glassing over old through hull openings
While surveying my boat's plumbing, I've found that there's one old unused through hull and one old unused depth finding sensor. (At least that's what it looks like, though I don't know why someone would go to the trouble of making a new hole instead of replacing the existing sensor.)
Anyway, what's the process for glassing in an old through hull? I've never done any glass work ever, but is this something that a glass kit you'd buy from West Marine could take care of? Do you fill the hole with some kind of hardening putty, then just glass over the bottom, sand and repaint?
Or is this something best left to a pro if you've never done it before? Considering you need that hole to stay filled, I'd think "pro" in my case, but I'm still curious.