If you're going to be spending any amount of time living on board you'll likely want to install a dockside water hookup and possibly a dockside cable hookup if your marina has cable.
These are common on newer boats and may or may not have been installed by previous owners.
If you do buy one of these boats send me a PM and I'll send along links to a bunch of C30 owner sites that have how-to articles on upgrades they've done. You'll find there are a lot of loyal C30 owners out there and a lot of documentation on these boats. Catalina also does a surprisingly good job of supporting their owners -- no matter how old the boat.
95 Catalina 30 Island Time
“If a man is to be obsessed by something, I suppose a boat is as good as anything, perhaps a bit better than most" - E.B. White