I'm facing a huge problem with naval battles in the game. I don't use any mod at the moment.

I have several Nanban Trade Ships in my navy as well as the Black Ship but I constantly get crushed by koboyas. This is ridiculous, with autocalc I easily defeat them but when I play manually even though my ships hit their target with 3-4 cannonballs at point blank range they don't sink the enemy ship and don't kill anyone.
As far as I remember cannon were fearsome in naval battles, what has happened to them? The only way I manage to do some damage is when the sailors fire their musket but most of the time they just walk around the deck and do nothing while they get peppered with fire arrows.

In short cannonballs cannot sink ridiculous small canoes but huge large ships get rekt by them? How realistic is that? What the use of making efforts to gain access to expensive ships if they are worthless?
Fire arrows shoul not even affect caravels that's ridiculous, even on other ships, I mean we are on water, it's not some fire arrows that are going to ignite anything...especially on large ships.

Do you all remember the famous battle of Tenochticlan when the Aztecs burnt down 10 spanish caravels by shooting fire arrows at them from their armada of canoes ? NO? That's because it never happened and would have never happened in under any realistic circumstances.

Do you know of a mod that increase the power of cannonballs or at least which disable fire arrows for naval battles ?