[piri_reis]

Just copying pasting my findings from another thread:

Resupplying at sea works.
There are Resupply Map Locations defined in some of the campaign projects, I didn't see any in the Total Germany 39 campaign but there were some in Operation Drumbeat.

How it works is, if you are in the range of the resupply location, which can be defined using the Mission Editor, you call for a resupply using your radio guy. He will give you coordinates to the rendezvous point. You'll meet with the assigned ship/submarine (again the class of ship can be defined) and the icon to refit/resupply will show up when you are about a km out..

I tried this by creating 2 resupply locations in the Baltic, my VIIB (!) supply boat showed up as planned.. I waited a few days to see if he disappears but after 3 days he was still there..

There also seems to be a minimum time between refits, because I kept getting denied at my 2nd resupply location..

How will you know in-game, where the resupply locations are? Well I haven't played that far in the campaign but I guess they will be shown on the map when available(?), not sure..