Measurement is center.
My capital ships never fly in squadron.

And escort squadrons are spread out if I face NC, when lines close they mass vs ordnance.
Also: if Nova Cannon is shot above 60cm the scatter is maximum 3x6 = 18cm. So with ships at 15cm I need to roll high plus the direction needs to be precisely correct.
Under 60cm the scatter is 2d6, so a maximum of 12cm, a ship at 15cm.... heh.
Under 45cm the max is 6cm.
And in both cases the direction needs to be good as well.