Sigh, no one ever listens to my rants. Suppose that's why I don't do it more often. Broadside won't work in BSF to any tactical advantage. Other than being cool.
They work for me.
If you have X main turrets, it's better to position them centerline with a large rotation angle, then to put X/2 on one side and X/2 on the other.
But then its even better to put them all at the front and have them all firing forward unless you are going to get surrounded.
Most guns on a well-designed BB can fire forward anyway.
You basicly have a choice betwen:
1. A ship that has practicly all of it's firepower fixed forward, and is very vunlerable on defense (since the enemy can jump in behind you) but devastating if it positions itself to bring all that power to bear.
2. A ship that has it's firepower spread around (so it can defend itsef from any angle and multiple lighter attackers), but positioned so that it can bring most of it to bear on a snigle target if needed (against big ships, asuming it positioned itself properly)
Basilcy, assuming equal weapons number and strenght, no1 ship will have a slightly biger power output when attacking a snigle ship, but otherwise, it's a one trick pony.
No2 will be able to bring considerable firepower to bear on a snigle target, almost as much as No1, but at the same time doesn't have other weakneses of such a design.
Thing is, that depending on positioning either ship can beat the other, but n01 will suck against multiple opponents compared to n02.