Was it limited visibility (i.e. fog)? If yes and the cruise
boat had radar
(I assume it had...) then one long means "single vessel going upstream".
If there was no limited visibility and the cruise
boat did not see you it was only an "attention" signal (more or less "here I come").
The two short is to signal that she can see you, she's moving upstream and she proposes you to pass by on her starboard. Your answer could have been:
a.) I agree: two shorts
b.) I disagree, pass by on port: one short
On which she could answer:I agree - one short (no answer means no I guess
(EU-HU inland water regulations
...just checked in a 2011 book