in one of the ports I have one barge laying around without fleet.
So it can't travel anywhere but it showed 4 hours and some minutes travel time with option for creating a fleet AND option for instant travel..
Clicked it and this message came up:
By using turns, this fleet can reach its destination immediately. For every ship in the fleet, you will need 1 turn per 10 minutes of remaining time.
You do not have enough turns to command an immediate move. You need 1681209 turns for this but you only have 137.