Sabotage the Barrel of Grog, the Barrel of Gunpowder, and the Crate of Cannonballs.
Sabotage the Grog
Sabotage the Gunpowder
Sabotage the Cannonballs
The attack on Booty Bay is looming. You'll have to return to Booty Bay quickly and inform the Baron.
First, however, it might be a good idea to sabotage some of the pirates' supplies while you're still in their favor. The pirates keep most of their supplies belowdecks, spread out across the entire fleet.