scottyt, I guess I don't really understand what that device you linked is. It advertises that it lets you switch hoses without getting wet, which to me means that it seals when you disconnect it. That wouldn't seem to be conducive to draining the disconnected line. It also appears to have threads for a garden hose, so I'd need to find adapters to bring it down to a 1/2" hose barb. I doubt I can find a single-stage adapter to do that, I'd probably need two, unless someone can point me to a really comprehensive plumbing supply company online.
sailingdog, that is exactly what I need, but where do I get it? I can't seem to find the full selection of parts in the necessary sizes to build that.
Thanks for your help so far.
1979 Gulfstar 37 Laissez Faire