Since that Bellony was me I´d like to give my 2 cents of opinion.No matter what happens to the chain system (others have put more thoughts into it overall) I´d like to see a certain change happen. Therefore I´ll tell you a little story.
Let´s have a look at two different sailors, let´s call them Siggy Sailman and Carl Cannonman:
Carl Cannonman´s job is to aim the gun and load the gun. He is protected all around by other fleshy Humans and thick wooden boards. When the enemy cannons hit his deck there´s some bloodshed and broken wood but it´s as expected and the sand below his feet keep him standing and he continues to do his job. If things get too wild (reload shock) he might have some scary moments but will return to the fight immediately afterwards.
Siggy Sailman´s job is to work in the rigging he is climbing 50 feet above the deck and all that keep him there are some ropes and blocks. When the enemy cannons hit the rigging around him with chain its pure chaos. Many of his mateys fell into the water because some ropes got cut down and now he has to spot and replace the missing ropes so the ship can turn its yards again properly. (pretty much always a rigging shock)
What I am trying to say is. Rigging Shock should happen much more frequently but maybe sail damage should be reduced to whatever Havelock or Hachi suggested earlier. This way chain still retains its usefullness (along with a new tactical option, timing your chain broadside to make someone get stuck in a maneuver).
PS: Maybe add some minor crew damage when shooting at sails.