renown system is easy.
You get renown by killing ships, reaching the assigned patrol grid, staying in the assigned patrol grid for 24 hours, actually docking at your home port after the mission is over etc.
Upgrade your U-boat with new equipment by using your renown points to purchase the items available. or even buy a whole new boat.
be careful about using renown because the more you have the higher your rank becomes.
Renown is basically SH3 money
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