That is a very nice addition, the underwater hull is a welcome supplement for a very nice little passenger ship.
I might just add that the propeller looks a little small and thin, and I think you might want to draw another one. I know the image shared with you shows that propeller, but I think its more for show than actual representation of the real propeller.
I'll see if I can find some more resources on the propeller but if I can't I'll probably keep it the way it is.(Unless you have a standard propeller design that you think would work) Thanks Novice.