Hey Yall,
So this is just the AC layout. Still in the works on DC but would like to install AC during December if possible. Plan on only running 30 amp in the US but want to ensure easy upgrades. 
All comments greatly appreciated!
asked
Can someone critique my AC layout on a sailboat?
You show two 30 amp shore power connections. You can't combine these since you can't guarantee the two hot legs are on the same phase or even that the neutrals come from the same source. It is unsafe and against code. The only way to use two separate shore power connections is to provide separate paths (hot and neutral) from the inlet all the way to the loads.
If you parallel the two shore power connections and power just one of then, you'll have exposed pins on the other plug at 120 volts fused for 30 amps. That'll kill you.
You can't use a battery switch for 120 volts AC.
You can't combine the Multi output with the direct shore power connection. If your goal is to provide a bypass for the Multi, a switch that switches both hot and neutral between the Multi output and your shore power breaker is necessary.
A detailed wiring diagram showing all conductions and what's happening inside each box would be required for detailed review.
I suggest you consult with a licensed electrician that is familiar with boats and inverter technology (Victron experience highly recommended). If you get this wrong, you could blow things up or injure/kill yourself or dock workers. This forum is not really the place for critical review of designs and is actually against the guidelines. But we do try to help where possible.
Thank you Kevin!
Yes- I have a hired electrician who has just viewed the vessel. I have helped to wire homes and warehouses but never a boat so want to learn as much as possible. I learn best by reading then doing and learning from mistakes.
So the two 30amp's are plugged into a 50amp shorepower with a ponytail. If need be, I can just run 30amp since many marina's only have such (adjust within victron gx?). This is also for future upgrades if I need more amps for ac units, etc.. My reasoning anyway. I had the understanding this inverter was capable of such.
The battery switch for the 120 was to bypass the inverter if I needed to have serviced and could still run outlets, hot water heater, etc.
thank you again!
The only way to deal with a 50-amp 120/240 split phase inlet is to use a 4-wire plug. It is never acceptable to combine two receptacles. You then convert the 30 amp 120 volt single phase shore power to a 4-pin connector. These adapters are commonly available in the RV market known as "dog-bone" adapters. I'm sure something similar exists for marine use.
Inside the boat, you then need to treat the power as split-phase all the way to your loads. That is two legs with a common neutral. The shore power panel and the load distribution panel in your picture are single-phase only. You need to look for a split-phase equivalent.
All Victron inverter/chargers are single phase units. You need two of them configured and wired in a specific way to fully support split phase power. A half-way solution is to use the 120x2 Multi. It accommodated 120/240 split phase power but has a single 120 volt inverter. When split phase shore power is available, L1 goes through the inverter to the loads while L2 bypasses the inverter and ends up at the L2 output unaltered. When shore power isn't available, both output legs are fed from the inverter output. So 240 volt loads would not be powered. Another approach is to use transformers around the inverter/charger to accept split phase power and provide 120/240 volt split phase power to the loads.
The battery switch shown as an AC switch is unsafe for this purpose, plus it only switches one hot circuit. Also the 1+2 position would connect the AC input and output of the Multi together which could cause damage. You need a 3-pole transfer switch to switch your load panel between the output of the Multi and the output of your shore breaker.
