Wait a minute... a turret-sized light mortar has a very slow refire rate, a greater energy usage, and less efficiency, while the forward gun has a faster refire rate, very energy-efficient, and has a LESS chance of missing?...
AWKWARD...
Personally, many people think of spinal-mounted weapons as the most cumbersome weapons in all of man's history...
The advantages of spinal-mounts are that moving mechanisms are quite space-hungry, and with the added space to use because of no need to be more flexible in hitting targets (the weapon moves with the ship), the designers focus more on the ability of the weapon to do damage when aimed properly, which may let them have slower refire rates, but greater damage factors... Perfect for Cap Vs. Cap battles...
As for turret-based weapons, the designers would let the weapons be more flexible, normally as backups against small fighters, but not relying mostly on them due to fighters being there to protect them...
Logically: Mortars that would be used against caps would have a greater refire rate, whilst the Spinal-mounted Liberty Cruiser gun would be a gamble against a giant target: either hit and win, or miss and lose...
I won't complain if the cruiser would miss, if I would be guaranteed that if it DID hit, the cannon would DEVASTATE the enemy cap, maybe even kill the Battleship in one shot, even if it may have a 0.1 refire rate...
Summary: I think their specs should me interchanged... It's not logically based on facts... If it works on battle, then I salute it, but I suggest the proper way is that the cannon would be a slow, but Armageddon-like weapon-of-mass-destruction...
Hey... I'm just sayin...
(edit): The damage is A-okay... just the others...
(edit 2): a little off-topic, but I would really like to know of a ship that is quite strong on its sides (like the 16th century ships that exchanged broadsides with each other)... Might look cool to have a ship like that