the captain and thecrew bind themselves to the flying dutchman, this allows them to th locker without affecting them. As you know this is there job to transport th dead seaman to the locker. However, i believe Elizabeth can not board the ship for two reason. 1. Bill turner and Will discuss that this is no place for a living girl such as Elizabeth they believe it to be the wrong environment for her, hat it would waste a living persons life looking after the dead. 2. Only living people in the film boarded the dutchman while it ws away fom the locker(as you know davvy jones had stopped his duty of transportation) and so once a living persn boarded the dutchmen when goin to the locker they had to either bind themselves to the ship or go to the locker itself, which of course will wished neither fates for Elizabeth.
Hope that helpsxx