We have a vessel that was built to European standards. We are wanting to use US (4 wire) 240v shore power on the vessel that is European (3 wire).
There is nothing on board that is voltage or frequency sensitive.
The other item that we are trying to accomplish is a step up transformer to increase the 120v shore power (it powers a battery charger, then the batteries run a 240v inverter) to 240v.
In your same situation, with a European sailboat. Ours came set up for 230volt/16amp AC power and 12 Volt DC. So I am not sure if I can provide any relevant advice on the DC side if you are set up for 24 Volt DC.
If you talk to a marine electrician you will probably get the safe but expensive advice to tear everything from the shore power inlet to the breaker panel and convenience sockets (and the wiring in between) out and replace it all.
If you talk to the guy on the dock you will get the unsafe but inexpensive advice to do a little wire surgery.
I wasn't happy with either extreme.
Since we ended up already having a 12 volt DC system, I left that alone.
Decided to go with the 240V/50A US standard instead of the 120V/30A standard. Put in the right US shore power inlet, and within ten feet a new 240/50 main breaker. Immediately downstream of that a Victron Isolation Transformer capable of accepting 110V-250V and outputting 230V. Hooked the output from that to the existing AC system.
Got a couple of 230-110 step-down transformes for $150 to use US standard stuff at the existing convenience sockets.
End result is the boat still thinks it is in Europe, I can run it as is for however long I want, and I have the initial setup for a very safe ABYC compatible US 240V/50A installation already in place if I decide to replace the original AC breaker panel, convenience sockets, water heater, battery charger and wiring in the future.
Hope that helps.