Pam;
I know the Catalina 30 website has the original wiring diagram for an average Cat. 30.
I've found a few 'after market' wiring diagrams for Catalina 30's, most were done after a rewiring job and are specific to each boat.
I included mine and a few that I used as help during my rewiring project. Mine may not be up to standards, but it gets the job done and I'm sure someone elses would understand it.
Good luck
Chris
on a side note, the one I included of my new engine panel shows an ammeter. I took that out and replaced with a voltmeter. So the wiring on the diagram now goes to the house reserve to measure that bank...