Realistically I think the underwater. hull would still be red. I don't think they had time to get her in a drydock to paint the whole hull. For the movie several subs were used! The pink one was a Balao class and it was full pink: there are some underwater sequences showing the pink hull ( also if ...
It is a quite famous ship and it is considered the first "ghost ship": it was found without crew and passengers close to Gibraltar. Also the painting is quite famous and gives the proportions of a typical "merchant brig". As said Acelanceloet it would be a quite challenging start but as said Mohamad...