The only way I have made them work is to make sure that they have a destination and there is only one routine convoy for each destination.
If I break the first of these rules the convoys sail to the most exposed base if they sail at all
If I break the second the convoys begin to behave as fully computer controlled routine convoys, i.e. they stop sailing where I want them to and immeadiately set sail for my most exposed outpost.... They only continue the shuttle runs to where I want them to go if it's just one for each forward base.
They are OK for automating the Truk to Rabaul & Truk to Shortlands fuel runs. But that is about it IME.



