At tech level +1, a ship has an extra 50 0x0p+0rmour
(rounded down). This extra armour does not cost
any mass, though the point cost of the (base) armour
is doubled. For example, a Centuari warship with 10
points of armour, costing a base 20 points and 10
mass, would have 15 armour circles on the SDS, and the
total cost would be 40 points.
The extra armour is placed in a row above the standard
row of armour circles. Damage is applied to the extra
armour first, and penetrating damage goes through to
the primary armour layer rather than onto the hull. A
second roll up will penetrate through to the hull.
Extra armour is treated as shell layers as for the
Phalons, as described in Fleet Book 2. A better
description of how it works as regards damage is
given there.
At tech level +2, armour is doubled. Armour cost is 4
points per point of armour, which costs 1 mass.
However, for no extra point or mass cost, there is
a second layer of armour equivalent in strength to
the first.