Star Trek Starship Deflector Shields

Deflector Shields

Deflector shields (so called because they deflect energy and physical objects from the ship to save it from harm, not because they have anything to do with the navigational deflector) are a ship's primary form of defense. They (and related types of technology, such as multiphasic force fields) are fields of highly focused spatial distortion created by shield generators and focused by subspace field amplifiers, within which generators maintain an energetic graviton field. Shield grids on the exterior of the hull shape the shield to conform to the ship (collectively, the shield grids are referred to as the shield matrix). When energy or physical objects impact the shield, its field energy is concentrated at the point of impact to resist the intrusion. Impacts are accompanied by a quick flash of Cerenkov radiation which humanoids perceive as a flash of colored light (blue for Starfleet shields, sometimes different colors for other species' shields.)

Shields are activated, or "raised," whenever threats to the ship become apparent. This could be an enemy attack, potentially dangerous emissions from a nearby star, or the presence of some enormous spacefaring creature. Shield modulation frequencies shift at random to prevent an enemy from adjusting the frequency of its weapons to penetrate the shield without resistance (on the other hand, adjusting the shields to match the frequency of a weapon can strengthen them against it). Raised shields interfere with sensors, so shield frequency rotation creates electromagnetic "windows" to which sensors automatically recalibrate to minimize this effect. (In game terms, shields without such windows impose a -1D penalty on all Sensors Tests (minimum of 1D is still rolled); Tests made when windows exist are rolled normally.) Often, however, Silent Running mode (See Operations Systems) comes into effect when shields are raised, so only passive sensor use is allowed anyway. Shields completely block transporters; no one can transport onto or off of a ship whose shields are raised.

Shields also interfere with warp travel. Software which controls warp drive and shield operation compensates for this effect. Without such measures, use of shields reduces a ship's Standard, Sustainable, and Maximum warp speeds by one-third.

Shields would interfere with outgoing attacks, except that Starfleet has anticipated and corrected for these problems. Torpedoes are equipped with shield transponders which allow them to pass through the shields unimpeded. (It might be possible to interfere with the transponder's signal, causing it to explode, but no workable means has yet been developed to take advantage of this idea.) Beam weapons' frequencies are set by the tactical computers to match that of the shields, so they pass through unhindered. (Theoretically, a ship could gauge another ships' shield frequency and sensing the frequency of outgoing beam weapon attacks, but rapid shield frequency changes during combat generally eliminates any chance of making practical use of this theory.)

Buying and Using Shields

Every ship has four shields: Forward, Aft, Port, and Starboard. Each one is paid for separately in terms of SU Cost; each shield must have the same characteristics (the Aft shield cannot be weaker than the Forward shield, for example). Each shield provides a certain amount of Protection. When Protection reaches 0, the shield collapses and the ship is vulnerable to attack on that side. Each shield has a Recharge rating which indicates how long it takes for it to return to full strength after collapsing or being turned off.

However, even while shields remain intact, some damage manages to "leak" through them from some attacks. This reflects the concussion damage to the ship from extremely strong attacks, sudden changes in inertia, and other factors. Each shield generator incorporates a subspace field distortion amplifier which provides the shield with a Threshold rating. Threshold indicates the point at which damage leaks through the shield. For example, if a shield has a Threshold of 1D+2, an attack which does 7D+2 will leak 6D through to the ship. Hull Resistance offers defense against "leaked" damage. A ship's Threshold cannot exceed one-third of its full normal Protection except in certain circumstances (for example, if a shield offers Protection 5D, its Threshold cannot be higher than 1D+2).

The accompanying tables describes the various types of shield equipment, their SU costs, and their effects. Each type of equipment - shield generator, shield grid, subspace field distortion amplifiers, and shield recharging system - must be purchased per shield (i.e., four times).

The Shield Grid indicates how much a shield's Protection and Threshold may be increased by providing it with extra power. Recharge cannot be improved in extra power.

Shield Generator	SU Cost	Protection
Class 1	1 x Size	0D+1 - 6D+2
Class 2	2 x Size	7D - 13D+1
Class 3	3 x Size	13D+2 - 20D
Class 4	4 x Size	20D+1 - 26D+2
Class 5	5 x Size	27D - 33D+1
Class 6	6 x Size	33D+2 - 40D
Class 7	7 x Size	40D+1 - 46D+2

• The base SU cost listed in the table indicates the SU cost for the lowest figure in the "Protection" column - for example, 27D Protection for a Class 5 generator, for each +1D+2 Protection beyond that, the engine costs an additional +1 SU. Thus, a top-of-the-line Class 5 generator, which provides 33D+1 Protection, costs (5.0 x Size) + 4 SU.

Shield Grid	SU Cost	Increase
Type O	0	0
Type A	0.5 x Size	0.25
Type B	1.0 x Size	0.33
Type C	2.0 x Size	0.5

Distortion Amplifiers	SU Cost	Threshold
Class Alpha	1.0 x Size	0D+1 - 1D+2
Class Beta	1.5 x Size	2D - 3D+1
Class Gamma	2.0 x Size	3D+2 - 5D
Class Delta	2.5 x Size	5D+1 - 6D+2
Class Epsilon	3.0 x Size	7D - 8D+1
Class Zeta	3.5 x Size	8D+2 - 10D
Class Eta	4.0 x Size	10D+1 - 11D+2
Class Theta	4.5 x Size	12D - 13D+1
Class Iota	5.0 x Size	13D+2 - 15D

Recharging System	SU Cost	Recharge Speed
Class 1	0.5 x Size	9 rounds
Class 2	1.0 x Size	8 rounds
Class 3	1.5 x Size	7 rounds
Class 4	2.0 x Size	6 rounds

Notes:

• All Four systems must be purchased for each Shield Arc, regardless of whether or not the optional Shield Threshold rule is used.
• The Shield Protection Rating is the TOTAL Shield Rating, NOT the per Shield Arc Rating.

Backup Shield Generators

SU Cost: 2.5 per generator (minimum of 10 metric tons) Most ships have multiple backups for their shield generators, to ensure that they can maintain some form of defense if the main generators are damaged or malfunction. Each backup 0.25 x Size (minimum of 10 SU); a ship must have at least 1 backup generator for each of its four shields.

A backup shield generator functions only when its main shield generator cannot work for some reason (typically, because of damage suffered in combat). When that occurs, the backup generator activates immediately to maintain the shields at their current Protection and Threshold, or a maximum of two-thirds of the shields' normal Protection and Threshold, whichever is LOWER. If the shield has already been reduced to 0 Protection, activating the backup generator has no effect - the shield systems' capacity for creating and maintaining the shield is too stressed and/or damaged to generate another shield until the normal Recharge period has passed (or the crew effects repairs).

How Shields Work

In game terms, shields have three main attributes: Protection (the amount of defense they provide); Threshold (the level above which damage "leaks through" the shields to affect the ship even though the shields have not collapsed); and Recharge (how quickly the shields come online again after collapsing or being turned off). Protection depends on the type of shield generator and shield grid a ship has; Threshold on the quality of its subspace field distortion amplifiers; and Recharge on its shield recharging system.

Protection

Protection is the total amount of defense a shield can provide, rated in terms of a number of dice. With a few exceptions, every pip of damage done to a shield by attacks reduces its Protection by one pip. For example, if the U.S.S. Redmond's forward shield provides Protection 26D+2 and takes 1D+1 damage from an attack, it now offers Protection 25D+1. However, this reduction in effectiveness does not reduce the ability to boost the strength of the shields with extra power. Each shield's Protection is separate; the aft shield can remain at full strength while the forward shield is at only half strength due to damage suffered.

Threshold

Threshold reflects a shield's (and, to a lesser extent, a ship's) ability to withstand powerful attacks. Even when shields remain intact (albeit weakened) after an attack, the force of powerful attacks can "leak" some damage through to affect the ship (all of the damage goes to reduce the shield's Protection). This occurs due to concussion damage from extremely strong attacks, sudden changes of inertia, explosions caused by overloading systems, and other factors. The amount of damage "leaked" through depends on the Threshold. For example, if the Redmond's forward shield has a protection of 26D+2 and a Threshold 5D, an attack which does 7D+1 reduces the Protection to 19D+1 and leaks 2D+1 damage through to affect the ship (Ablative Armor and Hull still apply to the "leaked" damage, of course). In short, Threshold represents the amount of damage from one attack against which the shields offer complete defense. A ship's Threshold cannot normally exceed one-third of its full normal Protection (for example, if a shield offers Protection 26D+2, its Threshold cannot be higher than 9D). This rule does not apply when the strength of the shields is increased with any other means.

If a shield's Protection drops below its Threshold, the Threshold drops to match the Protection. At no time can a Threshold exceed Protection. Attacks whose damage is equal to or less than one-quarter of a shield's Threshold do not damage the ship at all (they don't even reduce the shield's Protection). This is known as the automatic defense rule. For example, the Redmond's forward shield has Threshold 5D, so any attack which does 1D+1 damage or less does no damage at all; it doesn't even reduce the Protection of the shield it hits.

Recharge

Recharge represents how quickly a ship's shields return to full strength after the crew turns all of them off and re-activates them, or they collapse (provided, of course, that the shield generators or other equipment are not damaged in the interim). On most ships the Recharge is 45 seconds (9 rounds) - a long time in a combat situation. Some ships have faster Recharge rates. Thus, if the Redmond's forward shield is currently at Protection 11D, it can simply turn all its shields off, wait 45 seconds, and reactivate them (including the forward shield) at the full Protection 26D+2. If a ship turns its shields back on before the Recharge time fully passes, they activate at whatever Protection they were at when they were turned off or collapsed (in other words, Recharging for less than the full time accomplishes nothing). There is no way to decrease a ship's Recharge time other than to upgrade the shield recharging system.

Advanced Shield Variants

Since shields are so important to the integrity of a ship and the safety of its crew, much research has gone into improving them or developing new, more powerful types of shields. Players may buy the following types of advanced shields for their ships with the Game Master's permission.

Covariant Shields

SU Cost: 3 x Size (in addition to normal shield cost)

Covariant shields use an advanced, tetryon-based technology. They work like normal shields, but with one additional benefit: they interfere with sensors. They have the same effect as a sensor-reflective hull (See Specialized Hulls) when active. They cost 3 x Size in SUs in addition to the normal cost of the shields.

Metaphasic Shields

Developed in 2369 by a Ferengi scientist, Dr. Reyga, the metaphasic shield generates overlapping low-level subspace fields. This causes anything within those fields to partially enter subspace, which provides high level protection against phenomena is normal space. Metaphasic shields have the same weight cost as normal shields. However, their Protection and Threshold are triple that of a normal defector shield. Among other things, this allows a ship with a metaphasic shield to safely enter and spend time in the coronae of stars. (For obvious reasons, metaphasic shields can significantly unbalance a game; Game Masters should be very, very cautious about allowing players to have metaphasic shields for their ship.)

Multi-spectral Shields

This type of shield, available from 2370 on, uses multiple spectrums of energy, thus enabling the shields to recharge more quickly. To simulate them, buy a Class 2 or higher Shield Recharging System.

Regenerative Force Fields

Starfleet's latest advance in the field of defense technology is the regenerative force field, also known as regenerative shielding. Its name derives from the fact that it has the ability to "repair" itself when damaged. A regenerative force field siphons off some of the incoming energy of an attack into a field storage container, then uses that energy to recharge and strengthen itself, making it very difficult to ever completely collapse it.

When a regenerative force field loses any Protection to an attack (or other cause), beginning in the next round each shield can "regenerate" points of the lost Protection until its protection is once again at full strength (it cannot regenerate additional Protection beyond its full normal Protection). The number of points it regenerates each round depends on the type of shield regenerator purchased (see accompanying table), but cannot exceed the number of points of Protection lost to previous attacks. For example, if a Class 4 shield regenerator suffers 1D points of damage from an attack, it can only regenerate 1D points, not 1D+2. However, if previous attacks during that combat have caused it 33 points of damage, it could keep regenerating at a rate of 1D+2 Protection per round until it was back at full strength, even if the prior round's attack only did 1D+1 points of damage. Regeneration occurs per shield, not for all shields at once.

Regeneration ceases to occur if the shield collapses; however, all regenerative force fields automatically have Recharge rates of only 20 seconds (so there's no need to buy a separate recharge system). Shield generators, grids and subspace field distortion amplifiers are bought as normal. Normal shield rules apply. A regenerative force field can only regenerate up to its full normal Protection; if Power or enhancements are used to increase a shield's strength to the limits allowed by its shield grid, thos extra points do not regenerate.

To buy regenerative shielding for a ship, you must buy it for each of the ship's four main shield generators (you cannot build a ship which has, say, one regenerative shield and three normal shields). The backup shield generators automatically tie into the regeneration system; players do not have to purchase separate regenerators for them.

At present, regenerative force fields are found on only the most advanced vessels, such as the U.S.S. Prometheus. Due to technical and economic reasons, it will likely take some time before substantial numbers of Starfleet vessels are equipped with them.

Regenerator	SU Cost	Protection per Round
Class 0	2 x Size	0D+1 points
Class 1	3 x Size	0D+2 points
Class 2	4 x Size	1D points
Class 3	5 x Size	1D+1 points
Class 4	6 x Size	1D+2 points

Source

• Spacedock: The Advanced Starship and Construction Manual (pages 72-75, 125-126)
• thedemonapostle