As above for the single switch. The 30 amp main switch is:" Blue Sea 7238 A-Series White Toggle Circuit Breaker Double Pole 30A". You can google to find the best prices.
I had to redo my C Dory 25 panned, when I went with a 110 volt transfer system as part of the inverter/ charger install. I also moved the water heater (makes easier access to the panel.. and along with this lengthened the wires so it was easier to pull the 110 V panned out and work on it.