Valkyrien Pirates

G_Mungus made this mod a whole lot better:

Overview: Reworked cannon priming block:

Cannon priming blocks now convert the dispenser in front of them into a cannon dispenser block. Cannonballs only shoot out of cannon dispensers, which can receive redstone power through the priming block behind. An armed cannon priming block can be disabled by killing a pirate entity who crews the cannon. Firing cannonballs now has a new sound and particle effect. Now can be crafted.

Changes to motion invoking block:

Motion invoking blocks only work under a ship helm. They receive the ship's orientation from the helm instead of their own property. Can be disabled by killing a pirate entity who crews the block.

Changes to pirate entity:

Created new texture, model, and animation. Changed pathfinding to help the pirate not fall of ship as often. No longer teleports to the player. Can crew cannons or motion blocks, which allows them to be disabled upon this' death.

Rebuilt ship structure:

2 Variants, one small with no cannons and smaller loot. Mostly added for variety and ambiance. Other variant is med-large, with a dozen cannons and a larger crew. 2 masts, lots of treasure, interesting design.