1. Detection of enemy units -- ie sonobuoy, drone (perhaps short flight rocket with camera etc), German underwater sonar
2. Air Defense - Wasserfall
3. Sub to Ship guided weapon,
4. Anti sonar coating U480 :
https://en.wikipedia.org/wiki/German_submarine_U-480
The U-boat was
laid down in the
Deutsche Werke in
Kiel as yard number 311 on 8 August 1942,
launched on 14 August 1943 and
commissioned on 6 October 1943 under
Oberleutnant zur See Hans-Joachim Förster.
U-480 carried out three war patrols, all under Förster's command. Because of its coating, the boat was sent to the heavily defended
English Channel. The
Alberich worked;
U-480 was never detected by sonar.
5. Streamlining - Like electroboat (for faster underwater speeds)
6. Battery increases in boat -- longer duration under water
7. Dutch Snorkel
8. Japanese Long lance Torp
9. German zig zag Torp