The rear drains on my 2000 Seafarer 228 are 2 piece, like the one in the OP. The scupper itself is straight, and threaded, just like a 1 1/2" thru-hull. The elbow is straight off the shelf in any plumbing department, a dark gray PVC el, with female threads on one side, and a 1 1/2 hose barb on the other. Once I cut the hose out, I was able to reach under and unscrew the el. Put a new hose on a new el, loosened the drain nut with large channel-locks, and screwed the drain in from the top. Tightened the nut, and attached the other end to the transom thru-hull.
Peahead, the reason your elbow is dripping is probably because it is not even hand tight to the scupper, like mine was, not!
In hindsight, after wrestling with that old stiff hose, and knowing what is under there, I would just reach under there with the channel locks, loosen the retaining nut, and unscrew the scupper from the top. Then just remove the hose and el in one piece from the transom. Re-install in reverse, but don't connect the hose to the transom until you have a few good turns on the scupper to el connection. That will be my approach on the port side, where I have to deal with the battery charger and the oil tank.
I think one of the keys is to get hose that fits your fixtures , but not so tightly that it becomes a wrestling match to get them on, that's what clamps are for. I replaced with 1 1/2 sanitation hose. I see nothing in the photo of my old hose to make me think that it is the best for the job.