Star Trek Starship Cloaking Devices

Cloaking devices, a type of "stealth' technology, emit an energy field which bends light and other phenomena around a cloaked ship, rendering it invisible to both the naked eye and most sensors. However, while they're powerful weapons, cloaks are not without their drawbacks. They require enormous amounts of power - so much that a ship cannot use many other systems, including shields, transporters, active sensors, and weapons systems, while a cloak is on. The ship can, however, use its communication devices or passive sensor systems, and doing so will not reveal its location to other ships. Cloaking devices work in atmospheres, but may be effectively useless due to the presence of atmospheric particles and the like.

Starfleet dislikes cloaks, which it considers contrary to its mission as an exploratory organization, and does not use them. In fact, under the Treaty of Algeron, Federation ships are forbidden to use them. However, exceptions are occasionally made (most notably the U.S.S. Defiant).

In game terms, cloaks work by imposing a substantial modifier on all Tests made to perceive the cloaked ship or object (including Search Tests and Sensors Tests). See below for base Difficulties using sensors. Sometimes, despite the modifiers imposed by a cloak, a ship manages to succeed with a Test anyway; this indicates it detected some anomaly or "sensor blip" which may provide a clue that there's a cloaked ship nearby. The accompanying table indicates the SU cost and effects of various types of cloak. Typically a ship's cloak should have a rating equal to or greater than its Size.

A cloaking device has a small internal battery with enough power to operate it to cloak itself (and itself alone) for about five rounds. This power cannot be drained to use with other systems.

Class	SU	Effect
Class 1	3+Size	+1 Difficulty to detect ship
Class 2	6+Size	+2 Difficulty to detect ship
Class 3	9+Size	+1D Difficulty to detect ship
Class 4	12+Size	+1D+1 Difficulty to detect ship
Class 5	15+Size	+1D+2 Difficulty to detect ship
Class 6	18+Size	+2D Difficulty to detect ship
Class 7	21+Size	+2D+1 Difficulty to detect ship
Class 8	24+Size	+2D+2 Difficulty to detect ship
Class 9	27+Size	+3D Difficulty to detect ship
Class 10	30+Size	+3D+1 Difficulty to detect ship

Source

• Spacedock - Starship and Construction Manual (page 62)
• thedemonapostle