Complex sentence: With these victories Brandi is oficcial the U-boat commander with the most destroyed warschips on his name, he's not the u-boat commander with the most destroyed ships, that is Otto Kretschmer with 47 victories.
Split into simpler sentences: With these victories Brandi became the the U-boat commander with the most destroyed warschips on his name. However, he's not the U-boat commander with the most ships sunk, that honor going to Otto Kretschmer with 47 victories.