there is a renown chart floating out there, unfortunately the link in the post is dead. Maybe is someone has it they can post it.
However it is pretty obvious that an Aircraft Carrier is going to have a higher renown than an Old Split Freighter, even though merchant shipping was the priority. In game it really should not be an issue as you are unlikely to come across both in the same convoy/task force. Also in game and in real life if the even that you came across a AC/BB and a tanker would "anyone" really sink the tanker over the chance to sink a major military asset?
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