Gene,
Is that regular PVC pipe epoxied in? or the plastic tubes Centerline mentions?
Nope, that's good old fiberglass and resin. Kind of a PITA, but I like it, and I don't expect it to ever fail (part of the reason I like it!)
Threaded plastic drains were not an option for me, because my scupper holes are drilled so close to the cockpit floor that there's no room for the flange. But I didn't like the "cheap" look of plastic fittings anyway.
Just for grins, I'll show you how my process went. Here's what you'll be looking at when you pull out the old tube:
What I did was, I got in there with a Dremel and ground out some of the material inside, enlarging the tunnel, but keeping the outside openings the same. Then I applied thickened resin inside the holes, making sure to force it outward into the voids between the layers:
Then I rolled some fiberglass cloth around a dowel, stuck it in the hole, and rolled the 'glass around, smushing it into the thickened resin and further forcing the resin outward. Then I applied a little unthickened resin to the glass cloth:
Then sanded ...
.... then applied some white gelcoat I had on hand.
Like I said ... it was a PITA compared to either of your other options. I probably would have just used brass tubes, except that I was also ripping up some rotten cockpit floor at the time, as you can see through the holes in the first two pics. But now that it's done, I'm glad I did it. Funny how that seems to be the way it often goes.
If you have clearance for the flanges, plastic drains will be your quickest, cheapest option. The only downside (in my humble opinion) is, they look cheap and unattractive.
For a few bucks more, you can have factory replacement brass tubes. I don't particularly trust the brass tube design with its tiny little flange, but there are thousands of them out there, so with careful installation I'm sure they can be leak free for many years.