Wolfpack tonnage
 

Its too easy for most people imo .
There should be multiple convoys but always a close or close +medium or close + medium + far one according to player choice . Tonnage for the medium and hard game should be bumped right up and involve finding multiple convoys .
Easy game mode would be tonnage you can get with the close convoy to reach the tonnage requirement .
Medium and Hard mode you would need to find multiple convoys to reach the tonnage requirement .

Obviously the game would have to at least spawn 3 small convoys and the minimum requirement on hard could not be more than the total ships tonnage of the 3 small convoys minus a couple . Obviously the game would randomly spawn any combination of small , medium , large convoys .

The game just needs spicing up a bit .