Fire-linked weapons are identical beam weapons, projectile weapons, or missile launchers that point and fire in the same direction. In effect, this arrangement creates a single weapon (fired with a single attack roll) that deals greater damage than either weapon alone.
Each full doubling of the number of fire-linked weapons (two weapons, four, eight, and so on) increases the damage by one-half the base damage. For example, a fighter using two fire-linked rail cannons (damage 6d12 each) deals 9d12 points of damage with a successful attack. Fire-linking weapons adds +1 to the purchase DC of each weapon in the link; taking the above example, each fire-linked rail cannon would have a purchase DC of 31 instead of 30.
Variable fire links also exist, allowing the gunner to decide from attack to attack whether to fire the weapons individually (as normal), in a full link (as described above), or in a partial link. A partial link allows the pilot to fire the linked weapons in groups of two. Only starships with four or more fire-linked weapons can be fired in a partial link. The variable version of the fire link adds +3 to the purchase DC of each weapon in the link.