I doubt anyone knows what I’m talking about, but this has been driving me crazy forever and google has failed me, so I figured I’d ask here anyway.

About 10 years ago I saw a silent, black and white comedy/romance on TCM or AMC or one of those channels that plays a lot of old movies. The title cards were in English.

The plot was that an older woman with some money was going on a cruise, and she was taking along a younger, poor woman and pretending the woman was her daughter. (possibly the younger woman was an orphan, or a neighbor that was nice to her?)

On the cruise, the younger woman meets some rich dude (possibly royalty) and they develop a love/hate relationship that ends with them getting together. What I remember most clearly is an extended comedy sequence where the young woman and man turn on and off the lights in their respective cabins to signal to each other.

Does this rings bells with anyone?