through hull drain tubes in the floor

[Bushwacker]

Are these wires meant ti last exposed like that for 30 + years. They've been working fine until now, and I haven't really messed with them at all.

I recently replaced my combo light on bow with separate red and green lights on cabin sides to make way for an anchor bracket. Nav lights don't pull many amps, so the original 1972 wires were fine and I just spliced the new lights to them. If you've been putting a lot of amps thru a wire it'll get hot and oxidize; then the insulation WILL get brittle and when you scrape it off the outside of the copper wires will be black; if they've been submerged in sea water, you'll see green copper sulfate. Any black or green wires should be replaced. I've seen than on trailer lights and bilge pump wiring, but not on nav lights.

Here's one link to some photos of the scupper repair I did.
leaking scupper repair I stayed with the original brass tubes to get max flow area. You can use schedule 40 PVC but you'll lose a lot of flow area due to the thick walls. I've been out in enough big seas that I decided if I ever took one over the transom, I'd want to get that water off the deck ASAP, so the more flow area the better!