I'm at the 18 minute mark when the ship that all the adventures take place on (I believe), pulls out .....and the ship right next to it is a four funnel ocean liner that looks very much like White Star fame.
Okay, we know what happened to the famous sisters so is it Olympic? It's not likely since that was scrapped in the 30s.
My best guess is that it is either Windsor Castle, Arundel Castle, or Aquitania with the Arundel Castle coming out first.
The movie is 1945 with probably actual filming around 1944, so it is not after that. Of course, it can always be stock footage from an earlier decade but the ship of adventure looks a little too "modern" for the 1930's. It rather looks like, IMHO, looks like, mind you, the Andrea Doria head on, but that wasn't launched till the 50s.