How long? Not a clue. Started playing day one, and I've got three pirates at lev 40, two finished the BB, one not. NONE of them have fully mastered grenades (I think lev 20 is high enough
), but all are maxed on all other weapons. Pirate Four is pushing lev 33.
First one was a total mess up, but quite the learning experience. Two went quickly, and three took her sweet time. Four is trying a combo weapons/quest adventure, but not worried about finishing fast.