Well it is possible to get 110V from a 230V 50 Hz generator but would require a separate AC transformer. You cannot get 110 directly from the generator.
The European 230V is one hot wire and one neutral wire. The US "220V" is two hot wires and one neutral. Each hot wire is 110V between that hot wire and neutral or 220V between the two hot wires. So US 220 can be split but European 230 cannot.
I would get a meter and frequency counter to check the generator output but seems unlikely that the name plate on the generator would be wrong. Is it possible the boat
has a transformer that converts the 230 to 110?