Sail repair makes sense. Limited hull repair makes sense (watch Master and Commander and observe how much they were able to fix between the ambush at the start of the movie). One thing I haven't noticed is the ability to shuffle guns around. Guns can be "knocked out" but recoverable, which would allow you to save some guns that were "lost", much in the same way a wounded crewman would be a "casualty", and thus out of the battle, but not permanantly lost. But if most of the guns on one side were destroyed, one should be able to move the guns from the other side over, assuming the damage wasn't to the rope tie-offs, or the flooring, or whatever is needed to secure a gun. Unlike a modern warship, guns aren't "fixed" in place, in fact, many captains had much leeway in the configuration of their armament, and could shuffle guns around (they were only held in place by ropes, after all).

So if you lose most of the guns on one side and survive a battle, you should be able to balance the two sides after battle. Heck, you should be able to transport guns between ships, as well as crewmembers, to some extent (yes they're heavy, but there are lots of heavy stuff onboard, including much of the rigging and the spars that hold the sails up). I have yet to be able to shuffle guns around post-combat, however, maybe I just don't know the technique.