how can i resupply (fuel) ?

[Trevally.]

You can do this to get back home if you have run out:-

Save game and note the time that you saved and then exit to desktop.
Open your docs and goto here - C:\Users\Owner\Documents\SH5\data\cfg\SaveGames
Look for your save game (by date and time that you noted). It may not be the top one as those are auto saves - normally 3rd one down.
Open that folder and look for - GameplaySettings.cfg
open that file with notepad and it will look like this:-

[Current]
LimitedBatteries=true
LimitedCompressedAir=true
LimitedO2=true
LimitedFuel=true <<<<<<< change true to false
RealisticRepairTime=true
ManualTargetingSystem=true
NoMapUpdate=true
RealisticSensors=true
DudTorpedoes=true
RealisticReload=true
NoEventCamera=true
NoExternalView=false
NoStabilizeView=true
MPShowPlayerNames=false
MPShowTorpedoes=false
NoShipHealthBar=true
NoGunProjectilePath=true

Change the line to say "LimitedFuel=false"
save file.
Load your save game and you will have unlimited fuel so you can reach port and either dock or refit.

You can then change your fuel settings back to limited.