Chunnelling is the process where a starship (normally a Firecloud Class Cruiser) creates a temporary interspacial rift between normal space and subspace. This rift is an artificial wormhole, a maelstrom of energy that acts as a tunnel between two locations in space.
To open a Warp Chunnel, a starship with the Chunnel Initiator ability (usually a Firecloud) needs to have at least 50 KT of fuel. It then sets its Friendly Code to the Ship-ID number of a starship with the Chunnel Target ability (again, usually a Firecloud), which must be owned by the same player as the Chunnel Initiator, have some fuel onboard, have a speed of Warp-0, and be at least 100 light-years from the Chunnel Initiator. This causes a targeting subspace signal to be generated. The Chunnel Initiator then projects a beam of energy that creates the rift. The generation of this high energy beam consumes 50 KT of fuel from the Chunnel Initiator. This rift is anchored to the Chunnel Target.
(If there are multiple valid Chunnel Targets with the same last three digits as the Chunnel Initiator's Friendly Code, the valid target with the lowest Ship ID will be used. It should be noted that this could change between when it's set and when Chunnel occurs in the Host Order, most likely due to the Chunnel Target being robbed or towed.)
If any starship locks a tow-beam on either of the Chunnel endpoint starships, the Chunnel will not be created. The warp speed and waypoint setting of the starship locking the tow-beam do not matter.
Once the Chunnel is generated, the Chunnel Initiator moves into the Chunnel. This causes the Chunnel to start to collapse. As the Chunnel collapses it pushes the Chunnel Initiator, and possibly other starships that were in the same point in space, along in front of the collapse. This movement uses no fuel on the Chunnelling starship(s) other than that expended by the Chunnel Initiator to open the interspacial rift.
A starship belonging to a player other than the owner of the Chunnel Initiator, which is at the same point in space as the Chunnel, must have a speed of Warp-0, be cloaked, be out of fuel, or have a Friendly Code that matches the Friendly Code of the Chunnel Initiator, in order to enter the Chunnel (way point setting does not matter). Starships owned by the same player who owns the Chunnel Initiator can enter the Chunnel at any warp speed, as can all cloaked vessels or starships with matching Friendly Code.
If a fleet of enemy starships arrives at a planet that is hiding a Firecloud with its Chunnel engaged, it should be remembered that those enemy starships with a speed of Warp-0 will also enter the Chunnel. Generally, the only starships that can move onto a planet with a warp speed of 0 are those that are being towed or have been halted due to web mine interaction. In short, while none of the uncloaked ships that moved there under their own power will necessarily enter the Chunnel, any starships that they are towing will.
Needless to say, traveling through a high energy interspacial rift can have an adverse effect on starship systems. Any starship completing a Chunnel will exit subspace with its shields down. By the next turn the shielding systems will be functioning again.
Cloaked starships moving through a Chunnel will remain cloaked.
Interstellar phenomena (Debris Disks, Ion storms, Minefields. Nebulae, Star Clusters and Web Minefields) along the Chunnel route are safely avoided. However, any Chunnel opening to or from a debris disk will suck in the debris, causing all involved starships to be destroyed.
See also: Out of Fuel.