Hi Neil, Our (1974 C&C 30-1) sink and starboard cockpit rain was run exactly as you describe yours.
While our boat was out last winter we had thru-hulls and seacocks replaced. The company doing that work informed me the shared arrangement would not pass survey and is no longer permitted by ABYC. So, we separated sink and cockpit drains and now have an additional thru-hull. Ours was installed without an elbow but with a slight sideways S bend to create a bit of a p-trap with drain running to a new thru-hull at the aft port side of the cabinet below the sink. This is better for storage in the cabinet but worse for accessing the seacock. Overall I’m very happy with the install, feeling slightly safer knowing that some very unlikely freak accident will not cause cockpit to drain into cabin via galley sink. Happy to send a photo of new drain, seacock, thru-hull under galley counter next time I’m at the boat. Andrew 1974 30mk1 Gulf Islands, BC
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