While reading another thread in the Science forum about two subs that collided becuase their sonar blocking systmes were "too effective" and they didn't see each other coming, it occured to me: How do races like Romulans and Klingons, when traveling in an armada or groups of ship, or cloaking and declocking in attack, keep from hitting each other? The obvious answer would be that they communicate to each other, but if it were that easy the Federation would have found out and surely the Federation spies would have also.
I would think for long-distance, formation travel, they'd be in autopilot, with stuff like speed, relative position in the fleet, and following distance already decided. That said, however, unless there is some signal nobody's detected yet, I would think it would be impractical for a fleet to travel that way once there's any reason to have an erratic course. For instance, if you suspected you were being pursued by multiple Klingon/Romulan ships, I think it might make sense to fly into an asteroid field so they can't predict each other's maneuvers...
When I played Star Fleet Battles I would write down each hex my cloaked ship was in. Perhaps fleets are pre-programmed with coordinates for each ship. Your ship stays within it's pre-programmed coordinates and route when cloaked and flying in formation. Ships should be several miles apart from each other, allowing for drift.
I agree that the idea of holding formation and staying quiet is the most practical one for fleet movements from A to B. We haven't really seen cloaked fleets do anything more complicated than that, now have we? OTOH, we know that people in the Trek future are capable of creating signals that have finite range. For example, the gravitic pull of the deck plates doesn't extend to the outside of the ship, or even to the next deck above or below; apparently, this type of artificial gravity dies down much faster than to the square of distance. It wouldn't be implausible, then, for cloaked Klingons to be talking with each other via special short-distance communicators that cannot be eavesdropped upon because their range is too short. Or they could use highly directional signal beams, much like naval vessels use signal lights that can only be viewed from dead ahead. Such means would allow a fleet to make a synchronized turn without the use of classic subspace communications or other compromising signals. It would be tantalizingly like the clumsy maneuvers of naval vessels before WWII and the advent of ship-to-ship radio, rather akin to having a bunch of guys waving flags at each other. Timo Saloniemi