The ship has not yet left the harbour. It has only just cast off the ropes. If a storm is seen ahead it's crew will decide not to leave the safety they have. Also no one has costed the journey or planned the route and the crew may mutiny at any time deciding the ship next door will give them a better life and is far safer.
They may still decide to go to sea but nothing else, including the route and destination are yet decided. And, there is even a chance that discovery that there is no gold to be found and the captain and officers are completely untrustworthy and do not know how to sail the boat may mean that they will never set sail at all.