"Prosperous convoy" effect

[Aqu]

I was looking some of strategic effects and began wondering what on earth is the title mentioned thing. It says the convoy effect should be 100 which I'm apparently not. The game doesn' tell what it is currently nor does it explain what the heck it means or where I could see it (as a number). What should I do to improve it? (TFH and I'm playing as US).

[the smoking mค็็็็็n]

Originally posted by dafuki001:

its impossible

dito

[OXKART]

there effect list on a tab. far right i think 3rd down. maby the swords or under the swords. my games down or is go see. in there u may get the park for doing it. or wikipeada it. I think to get that one its mounthly total of convoys killed . I my self have never got it. but if u went subs with germany u can realy do some damage to GB early vs franch war. i left my AI controling the subs and they did get the worth in making them. but i would say lv up subs and making about 10 and skilling up the crew could be a first step . GB teck for destorys gos up fast so soon ur subs are worthless so its all ways been hard for me to spend much need fator or teck point in