Take cover behind the barrels on the left, there are two enemies in the vicinity. Wait for them to stop their conversation. Shoot the one closer to you; you can use either the bow or the stealth pistol.
Leap over to the ledge with the dead guard and aim at the enemy on the upper level. Search their bodies first, then take the stairs on the left.
When you reach a wall, bounce off it so that you could catch the interactive ledge. Start moving to the right. Where you reach the spot pictured on the screenshot, leap up to the higher ledge and resume moving right until you can pull up to another platform.
Stop at the main deck, select any weapon and shoot the pulley to free the Tackle. Approach and pick it up (reward: 100 XP).