Hi,

You are faced with the difference in 50 and 60 Cycles from the mains power. Most appliances with a pump run bad or not at all when you are running at a different cycle-count as where they were designed for. So if your boat is build for European shore power (230V/50Hz) you will find that several devices will run poorly on US 240/60Hz. Normally Amel puts stickers on those devices. For our boat it's the washer, dishwasher, watermaker and micro-wave that can't run on 60 cycles.
So using the inverter to supply those with power can work, depending on the consumption and type of device. Typically the washer takes a bit too much from the inverter. If you have the 2500W Mastervolt Mass Sine, it's actually only 2kW continuous, really annoying. Our Siemens takes approx 2200W when heating the water and turning the drum. Devices with large start-up current (watermaker) will also have problems.
I'm not sure if the switching logic that Amel put in a 55 is the same as in our (late) 54. If so then the inverter does not provide power if shore power is attached. These are just a bunch of relays in our case,  nothing to configure. On our Amel we have basically the same problem as Saint Martin also uses 60 Cycles. I'm still thinking about a solution without messing up the original design too much. As there are a few other things in this area I want to solve I'm still in doubt between a bigger inverter or a inverter/charger instead of the 2500W inverter.

Cheers,

Arno Luijten
SV Luna,
A54-121