Pushing The Engines Problem
Here is a NG problem.
When you push the engines to go past sustainable speed the Engineer makes a skill test. Okay.
Now once, you are at these speeds a reliability test is required each hour to keep at maximum speed or the ship drops out of warp and must be repaired. The realibilty test is a 2d6 roll plus the realiaibly mod of the engines against a TN10+Speed. THis means that most ships can't maintain max speed for more than a hour or so. For example a TOS-era Constiution class going at Warp 8 with Reliabilty D (+6) engines would need to roll a 12 on 2d6 to contiune at max warp after one hour. This is typical of the TN's for most ships. About the best is something with the LF-47 engine (TN18, with +8 relaibility means a 1in 6 chance of pushing the engines for more than an hour). This doesn't make emergency speed very useful (can't get far in an hour, even at warp 9.9), plus it doesn't fit in well with sources that say that most ships can mintain max warp for 12 hours or so.
How do we calculate the TN for TNG er ships with wf9+ max speeds. For example a Galaxy-class starship has a max of 9.6, is this a TN 19 (10+wf9), 20 (10+wf9, +1), or 25 (10+wf9+6)? (with a +6 relaibilty mod the ship needs to roll a 12+ just to make the 19!).
Maybe this should be a engineering skill test (modifed by relaibilty) rather than a straight reliaiblty test?
Maybe the TN should be a bit lower. How about starting at the ship's warp speed and increasing 1 per hour?
Maybe the TN shouldn't be set by the actual warp speed at all, by by how hard you push the engines. My theroy being that running a PB-4 engine (wf 3/4/6 reliability B) at Warp 6 is probably pushing that engine as much if not more than pushing a PB-32 engine (wf6/7/8 Reliaiblity D) at Warp 8.
Maybe a ship can travel a max warp for 2xrealiblty mod in hours before it needs to make the relaibilty test?