The Gemoro on 79b says that when hiring a non-specific boat to carry non-specific wine (Sefina Stam v'Yayin Stam) neither side must carry the full responsibility. I am not clear on the case - if a boat sinking is like being lost (aveida), I would have thought the hirer is responsible, whether he specified the load or not, and if like Oness or Meisa Machmas Melocho I would have thought the hirer is not responsible, just like any hirer's responsibilities.
Why is it different here?
The Gemara is not speaking about the responsibility for the boat itself. It is discussing the responsibility to pay the fare.