Not sure what an “inboard” sink is, or where an “outboard” sink would be. (Overboard, maybe?) Attached is a photo of my now-9-year-old upgrade for the galley sink elbows, PVC pieces with the necessary screw cap fitting that I almost certainly got at Home Depot. Silverheels’ forepeak sink was long ago replaced with deep tool storage for my work bench there. The head sink’s version of an elbow is surely original, brass (or bronze?) seemingly brazed onto the bottom of the sink’s threaded drain tube and bent about 75-degrees towards the thru-hull. Once you’ve cut the brazed brass off the sink drain tube, if you can’t find a matching PVC elbow with the right size screw-on fitting, you might instead just clamp on a length of hose with an I.D. equal to the O.D. of the drain tube. Your sink will then have a nice, wide, smoothly-curved drain to the thru-hull instead of the skinny, bent tube Pearson put on there, which is prone to clogging.
Silverheels, P-424 #17