What is the way to expose a ship's powder stores

It's a pain in the neck. You need to ram the ship in the bow. Chain shot helps to disable the ships. It took me a lot of tries, but it can be done that way.

I know this an old thread for an old game, however for those that play this years after. Best way to complete this mission is to either let the ship ram you or you ram them head on (the tip of your ship hits the tip of their ship). This immediately exposes their gunpowder reserves. Took me a LONG while to figure this out. Make sure to hit the frigates at half mast or the ramming force could sink them

I've tried with heat shot, it takes a lot of damage, but in close range. After the second hit, it show the weak point for the small weapon. At least this helped me with Man-o-war ships.