Geomagnetic storms are generated by the interaction of the local magnetic field with the solar wind. To make it simple, the magnetic field vary a lot, and as we know from Maxwell, this induces a current in any loop wire crossed by that field.
Good news: you carrier, despite large, is still smaller than a land city or region, therefore it will intercept a lower portion of the varing magnetic field. The possible induced current is then lower.
Good news 2 Carrier electronics should be designed to protect them against induced currents.
Bad news A carrier is mostly made of steel, which has the ability of reinforcing the magnetic field, unless it has been realized as non ferromagnetic (magnetic mines are a well known thing in warfare). this will partially conflict with the first good news.