[KaleunMarco]

Originally Posted by uboot556

So,the best solution for this problem is to change manually "UpgradeClass="setting?
If yes,how?

jumping in here as PB is probably busy....

there is a folder at Data\Submarine that contains separate folders for each subclass. in each sub folder there is a UPC file for the submarine. use a text editor like Notepad, which comes with every Windows operating system, to edit that UPC file.

firstly, you can make these changes in Data\Submarine or you can create your own Mod folder for these changes. i recommend the latter technique but it is your choice.

Use Notepad to open the UPC file.
very early in the file text there is a line:
UpgradeClass=4

you can change the numeric value to whatever you choose as long as it is an integer.
for example, i am playing GFO at the moment. Here are the UpgradeClass values:

S-class boats - 0
Porpoise - 1
Salmon & Sargo - 2
Tambor & Gar - 3
Gato - 4
Balao - 5

it is probably best if you inspect each class' UPC and make your installation compliant with how you want the upgrades to proceed. for example, if you want to play both Salmon and Sargo then make those two different and consecutive values. same for Tambor and Gar. and, yes, you can use any numeric value as long as it is an integer.

go ahead and dig into it and see what you find.
good luck!