100% accurate data would be unrealistic in my opinion because ships draft is very variable in real world and it depends of many factors , like water salinity , ships weight ect...Even in the game, ships draft will also vary due to some game engine issues with somewhat realistic outcome...

I'm trying to get rid of XXI century computer accuracy in this expansion , not to enforce it, if you understand what I mean...
Plus, 100% accurate draft info will also be somewhat useles if we know that TDW generic patcher actually randomize torpedo depths. You think that torpedo set to 5.5 m will actually be on that depth? I dont think so...
Also Penguin and Ehrenfels data are irelevant because I guess no one will try to actually aim at those ships ?

Those are Germans goddammit...
I think that their values are taken from the real historical data related to these ships...