ok, so the convoy mission isnt a convoy at all, but more of a CTF game.
Dont get me wrong, I love CTF, but not as convoy.

When I first got into NF, the training mission had AI controlled boats. You could have merchant ships in a flagship selected formation and your team could arrange themselves around it.
Have a few runs to take you team accross the map from point A to B with the other team there to ambush/attack. Teams would alternate every round.
now ambushing team would TW, but escorting team could gain exp/cash is they take a torp thats in close(1-3 seconds away)/direct path of a merchant ship.
exp/cash would be awarded for ships successfully escorted
exp/cash for merchants/military tonnage sunk.

I donno, just to give it a convoy feel.

Also like to suggest(yah, lots of ideas today, but dont wanna seem like a exp whore), an ingame vote-team balance