I was thinking of a washdown/cockpit shower combination... what I really want is to limit the number of systems on board and yet still have convenient washdown and shower capabilities.

So is there any reason I should not put in a Y valve that allows me to switch from saltwater to freshwater at the same hose bib/connection?

This is just an idea I am toying with... and from a water saving standpoint it also has merit... soap up with salt water, then rinse with fresh water. (there are saltwater soaps)

Of course I could have two separate connections... one fresh and one salt, and just move the hose as I go from one to the other... no doubt "safer." Like I said... just toying with the idea.