Board Thread:General Discussion/@comment-24589671-20150323010258/@comment-413929-20150323013742

Elsa had help from the Rock Trolls to keep her kingdom safe, My guess is, since Disney made it clear that Elsa is good, her heart too pure to stain with any black, she shrank and trapped the ship rather then destroy it and everyone on it to protect her kingdom. Not knowing at the time that Ariel was there and in range of the spell at the time

It was good that Elsa got a mention though