Good luck getting those wires out of the Catalina 30. Been there done that. Most of them were installed before the cabin liner went in and WILL NOT come out no matter what you do. You'll likely need to get creative unless you want to split the deck from the hull then the deck liner from the deck.
This is always a problem with a fiberglass deck liner. You may also find that those wires used in 1979 were undersized for the loads. On my boat it was loaded with 16ga & 18ga wire. The 16 barely meets ABYC min standards and the 18 does not meet it.
Use a good quality UL tinned marine wire and you'll be fine. Also use the right crimping tools, don't skimp here, and use good quality connectors from Ancor, FTZ or AMP.
I prefer adhesive lined heat shrink/crimp connectors but most won't spend that kind of money to do it top notch. If good wire and good adhesive lined heat shrink connectors were used originally you would not be re-wiring today.
Just get creative and forget about running it between the liner and deck as it is likely nearly impossible. I snapped many wires trying to do this on a C-30..
Originally Posted by theartfuldodger
I rewired my Morgan O/I and used the bigle with very great results, which has also permitted me to do further upgrades, with other new installations.
188.8.131.52.6. Current-carrying conductors shall
be routed as high as practicable above the bilge water
level and other areas where water may accumulate. If
conductors must be routed in the bilge or other areas
where water may accumulate, the connections shall be