Well, I have been busy with raccoons in the attic for this past week, and have not had the time necessary to dedicate to serious attempts at getting my Win10 laptop going with SH3. I have a Steam version, and something either they or Windows did with their recent updates trashed all but my Stock copy, which I then proceeded to ruin trying to get NYGM & GWX back up and running, so I have not been able to begin to attempt to look at what my set-up would do. All I can suggest would be to make certain you haven't accidentally overwritten the AI Visual, or sonar, etc., since it seemed to me that NYGM was rather adept at seeing my periscope if I kept it up while moving... although 11ms winds will whip the waves pretty good...
- but 500 meters is rather close... Is the convoy zig-zagging? Had it recently turned?