I think it's more that the first episode of a season really sets the tone of a story arc, and it was shaping up potentially badly, both with being confined to a boat, and also the hint of already devolving to comic book villians like TWD before even fully exploring the walkers. Also, starting off with such a weak and dull episode wasn't reassuring for the ongoing quality of the show.
However, in the past two episodes, the boat has actually been used to keep the scenery fresh each week rather than getting stale being stuck on a farm, or at a prison, etc, and the plot development has been good, and the water has proven to be an interesting setting for walkers so far.