I think an interesting mechanic would be to have a system where if your mast hits a certain damage threshold WHILE it's at a certain sail percentage, you loose the mast. IE, if my mast gets hit and is reduced to 75% of it's HP and I am at 100% sail, then I lose the mast. However, if I was at 80% sail power or lower, I would keep the mast. However, if I go to 100% and my mast has less than 75% HP I would lose the mast. Implement a system like StaleMeme's post from August 16th so that we as players can judge what sail power we should be at.
Example heavily damaged main mast.:
This would make it so that hitting a mast still is valuable for combat (forces your opponent to lower their sail power) all while adding a skill based system (being able to judge the damage your taking as well as analyzing enemy firing habits) to those on the receiving end. It would also make lowering your sail power something you would want to do, because as it stands there is almost no reason to lower your sails since you can just slow down by back winding or manage your speed by intentionally managing them poorly.
It would also reduce mast sniping since you could just react by lowering your sails and repair the damage later, and incentivize firing broadsides in order to catch the enemy by surprise.
Final thought: Damaged masts can be repaired, but if you lose it, you can't bring it back. That way you have an incentive to bring down your sails.