Star Trek Starship Armor Systems

Ablative Armor

Starships designed and built from the late 2360s onward can take advantage of new defensive technology called ablative armor. When an incoming beam or missile strikes the hull of a ship, the ablative armor first distributes the energy of the attack around the hull via its initial radiative/conducting components. Then, when the energy rate exceeds the armor's conductive capacity, the excess begins to boil the armor off, thus dissipating the force of the attack and preventing it from reaching the interior of the ship. In the case of beam weapons, the high-density particulate cloud also interacts with the relatively low-density energy of the beam to carry off some of its destructive force.

In game terms, ablative armor acts like extra Hull Resistance, but only provides protection until it is destroyed. Each ten points of damage done to ablative armor reduces its effectiveness by one pip, round up; when all of its protection is gone, the armor has been completely destroyed. Thereafter the ship only has its normal Hull Resistance to protect it. Apply damage to any existing ablative armor before applying it to normal Hull Resistance. Ablative armor offers no protection against the effects to which a ship's ordinary Hull Resistance does not apply, such as gravimetric shear.

Example: The U.S.S. Indomitable has 3D of ablative armor. It's hit by an attack which, after shields are applied causes it 23 points of damage. This damage hits the ablative armor, which stops 11 points' worth of it, boiling away under force of the attack as it does so. The remaining damage is then affected by the ship's Hull. Because it resisted 11 damage, its further resistance is reduce by 2 pips. If the Indomitable is hit by a second blast, its ablative armor only has 2D+1.

A ship of Size 4 (149 meters) or smaller may only have up to 1D+1 of ablative armor for capital scale vessels and 3D+2 for starfighter scale vessels. A ship of Size 5 (150 meters) or greater may have up to 3D points of ablative armor for capital scale vessels and 7D+1 for starfighter scale vessels. Rebuilding or replacing ablative armor requires the facilities of a starbase, space station, or similar installation.

Source

• Spacedock: The Advanced Starship and Construction Manual (page 20)
• thedemonapostle