On September 5, 2021 Anonymous kindly provided the following comment:
Sea trials of latest Japanese submarine, Taigei (SS-513) have started [1]. The fin of Taigei-class submarine (Taigei) is longer than the fin of Soryu-class submarines as shown in video and picture [2, 3, 4].
[2] See a clear, full side on, view of the length of Taigei's fin 1 minute 50 seconds into the same video.
[3] Compare this with the appearance of the fin length of Soryu Mark 1 Hakuryu
(SS-503) below. See Wiki entry for Soryus and Submarine Matters'Oyashio-Soryu-Taigei TABLE (by scrolling one quarter down here).
[4] The all important Length/height ratio of the fin is 2.4 for the Taigei-class and 2.1 for the Soryus (including Hakuryu).
Pete Comment
Reasons for the longer Taigei fin may include the Taigei accommodates, or can accommodate, more masts, antennas and a larger sonar sensor area (if a hull mounted sonar extends to the fin). Also the Taigeis may/will have Japan's upgraded (tolerates higher sea state) snorkel - which may have different space needs.
Other reasons maybe - Taigei's fin may provide:
- greater hydrodynamic efficiency
and
- quieter acoustic signatures (see "reduce fluid noise") against:
= opponent's passive sonar and
= overall lower profile fin for improved sound wave deflection against active sonar
"interrogation".
"interrogation".
Anonymous and Pete