WW2 German Death Card of Kriegsmarine member Fritz Weinzierl.

According to the card, Fritz(Friedrich) was was a Pupil at a training school working towards becoming an Unteroffizier. He was also serving in the Kriegsmarine. He was only 17 years old when on June 14th 1944 he was killed in action near Boulogne, France. I’m unsure of any details about how he was killed. The German war graves has his date of death as June 13th not 14th so I’m not sure which is correct. Based on research I’ve done there was a Type R-41 minesweeper that was bombed and sunk on June 13th in Boulogne by a Bristol Beaufighter aircraft. So Fritz may have been on board but I’m not sure. Any other information on him is greatly appreciated.