technically all you've done is make either a torpedo boat (patrol boat) or destroyer, in regards to WWI / WWII era ships.
Destroyers had arrays of 6-12 torpedo tubes at the center of the ship that could turn to the side and fire torpedoes off into the water, to combat larger vessels.
The equivalent to this in discovery is a destroyer-class ship (destroyers really should be smaller and more agile than cruiser counterparts, but most of them arent) with light mortars loaded.
The problem is that light mortars take ridiculously high amounts of energy to fire - 500k? Seriously? Tone it down. Nobody in their right mind uses those heavy hitting special weapons when normal turrets only do slightly less damage and have no energy drain whatsoever on your ship.