Moving convoys with one waypoint
Normally, you may think it would require a waypoint for each ship in the convoy to make them move. That's not necessarily the case. Using only one waypoint for all ships is possible if the convoy ships form a wing and you intend them to jump out after a given amount of time. You may randomize this value using the rand operator or make it difficulty level-dependent by using Events. Put the waypoint far, far away and make all the ships face and move towards it. If you have placed the waypoint far enough, you will get a high number of time needed to reach the destination for the convoy. The ships need not reach the waypoint, obviously, use Events or Departure Cue to order all the ships to leave. Its setback is that the player will not see the real estimated time of departure on his HUD.
If possible, avoid referring to wing names in the has-departed-delay SEXP. If all ships in a wing leave individually, it will not make FS2 notice that the whole wing has departed. Instead, list all the ships one by one or use the percent-ship-departed SEXP.
Should you intend to use Wing names in the has-departed-delay, make sure that in the Wing Editor, the Departure Cue becomes true before all the ships jump out. Logically, if you do not find it important that each ship leaves a different time, you might use the Departure Cue to order the whole wing of ships to depart at the same time.