So...I'm a newbie, but enthusiastic never-the-less. I've got a new to me, 78' Catalina 27 with wiring so bad I almost cried when I pulled the DC panel out. Calling it a fire hazard doesn't even come close to what's in the boat.
I couldn't even count the badly soldered wires hanging off the panel bus bars. Several attempts were made to bypass the fused circuit. Ugh....
A look at the battery bank showed a starter battery and a house battery. The house battery had about 8 home runs to the positive terminal. Two of the wires had broken off their badly crimped ring terminals and were just hanging out. A short just waiting to happen.
Clearly a complete rewiring was in order.
If any of your "smarter than me" people would be kind enough to have a look at my fresh off the press wiring diagram, I'd appreciate it.
Most of the major issues are on the AC side.
AC Wiring is: Black = Hot, White = Neutral & Green = Earth/Grounding Conductor
You can't take an On/Off switch and an outlet straight off a 30A AC feed it needs to go though the double pole breaker then come off a "branch" breaker on the AC panel.
The battery charger gets powered/run off an AC panel breaker
With a non-marine UL inverter is it up to you to make sure that when the transfer switch is in the ON position that the inverters neutral and ground are bonded together because it is now your "power source". When the inverter is OFF there should be no Neutral to Ground bond on-board. Most cheap inverters do not connect Neutral to Earth (unless there is an internal failure of the inverter) and this can create a human safety issue. A proper marine inverter creates the correct neutral/Earth pathway switching.
Inverter ON = Neutral and Earth bonded (continuity) at inverter
Inverter OFF = Neutral and Earth UNBONDED on board the vessel.
Make sure your shore/inverter transfer switch can be wired to properly to create the correct neutral (white) & Earth (green) wiring for inverter ON and inverter OFF.
AC grounding (green) and DC ships ground need be bonded on-board the vessel but AC Neutral and AC Green must remain unbonded unless your inverter is actually operational.
You show a 30A in-line fuse on a red AC feed. With AC power the main feed must break both Neutral (white) and Hot (black) simultaneously. This is in the form of a double pole main breaker. If the main AC breaker does not have a reverse polarity circuit then all branch breakers need to be double pole breakers.
If your main triplex wire feed to the AC panel is longer than 10 wire feet then you need an additional
30A double pole breaker at the 30A inlet.
If you plug into shore power then you'll want a galvanic isolator at a bare minimum..
Any AC connection needs to be made with access only by tools. Power posts are not ideally suited to or used for AC work.
As has been mentioned most of the items on the AC list can all be run directly of DC 12V. They will run considerably more efficiently than they will off an inexpensive PWM inverter and use less battery power..
A separate starter battery, with a 9.9HP pull-start motor, is really quite a bit of overkill. Combine both batteries into one large bank and they will easily start your motor even when dragged down to 90% DOD with ease. Now all you need is a simple ON/OFF battery switch.
On a vessel like a Catalina 27 the only things on a 12V "always on" circuit should really be the bilge pump and a stereo memory wire, if you really need it.. Putting too much on the always on
circuit leads to dead batteries far too often. As many circuits as can be turned off with one switch
is always the best design foundation to start from.
My overall recommendation = SIMPLIFY:
*Ditch the entire AC system - Most of your complications revolve around doing AC safely and correctly.
*If your dock offers 15A or 20A 120V AC simply use an extension cord for the battery charger, when dockside, and plug directly into the charger.
*Make starting battery part of the main bank and keep a single ON/OFF switch
*Put everything on the switched DC panel that you can other than the bilge pump and perhaps the stereo memory, if your stereo really requires it.
*If you must have an inverter wire it direct to the bank with proper fusing and use the GFCI outlet on the inverter as your AC source..