help needed for novelist

There are at least two known special operations where u boats put saboteurs ashore on the east coast.

If they didn't exchange info by face to face to contact, meaning on the surface, it seems it would have to be by radio or light signal.

The Allies were decoding a large portion of the German Navy's radio traffic until early '42 when the Germans switched codes. The Allies did not break the new code until late in '42. During this 'blackout' period the only signals intelligence the Allies had on uboat deployment was the 'huff duff' direction finding system, but it wasn't very accurate. During this blackout period, the Allies obviously wanted to break the new code very badly, and it may have been possible for someone to broadcast briefly from very near the shore. I'm not sure if uboats surfaced to recieve instructions while very near the coast, but if they did, it might have been possible for a spy to transmit a low power signal that couldn't be read in this blackout period, and the 'huff duff' wouldn't have been accurate enough to tell the signal was coming from shore.

Make the girls father an intelligence officer in the US Navy...

Shifty eyes, weak chin, dandruff, humped shoulders, dirty shoes, nervous tic in one eye, 'foreign' accent or how about Short blond hair, combed back and oiled, small pencil moustache, duelling scar across one cheek, monocle, tendency to shout, interest in falconry, and a love of Beethoven and Wagner played at high volume.

Ask both of them who played third base fielder stop for the winning team in the 1932 World series and see which one answers correctly. OK, sugar ?

Could signal with a light using some code. The girl could see th silhoute of the boat....not know what to think until she hears somebody talking about a possible spy.