If you and some other scallywag of a pirate were destined to join forces, peacefully in the future, would you benefit more by adding a fully equipped galley to your growing armada or a weak scurvy ridden dingy? Now if you intended to add this ship to your armada by force, if need be, you'd want them to be as weak as possible. You wouldn't want to take too much damage to your own fleet for the acquisition.