While on an expedition, ye'll see yer new tools on the toolbar at the bottom of the screen. Cutlass icon on the left is for Deckhands, cannon icon on the right is for Cannonballs.

Cannonballs work exactly like Bangs. Tap the cannon icon on the toolbar >> place the Cannonball >> confirm the action, and it will remove 100 units of the nearby objects. See? Fish in a barrel! Deckhands are hard-working fellas who will do anything to earn yer respect. One Deckhand can remove any object regardless of its size, so ye better use them with big objects. Let them show what they’ve got!

To use this tool, tap the cutlass icon (the icon will go blue, which means the tool is activated) >> choose any object >> confirm the action. After ye use a Deckhand once, ye’ll have to tap this icon again to activate the tool.