Visible accidents are very rare in the Japanese Submarine Service. There has been a veritable avalanche of information and comments about the February 8/9, 2021 collision between:
- the 3,000 ton Japanese Soryu submarine, specifically first-of-class "Soryu" (SS-501)
- with the 51,000 ton bulk carrier ship Ocean Artemis.
1. Perhaps the most useful written report, so far, is The Drive's“Veteran Submariners Explain What Might Have Caused Japanese Submarine Collision” of February 9, 2021. The report poses various combinations of:
- submarine hit from behind by the ship or hit side-on by the ship [Pete comment: either way a very slow to change course ship generally has the right of way. This is because the sub ascends into danger - like a pedestrian stepping into traffic.]
- the sub being below periscope depth, at periscope depth or surfaced
- in a position of poor coverage by the sub's sonars or inadequately monitored/interpreted sonars and/or the periscope
- the sub was in relatively shallow/continental shelf waters which can confuse sonar returns.
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2. Anonymous has identified sankei.com's article "Mistake in manoeuvring due to lack of crew training in inspection or accident of JMSDF submarine "Soryu"" of February 10, 2021. In that article an anonymous Japanese government official (once translated) suggests:
- the sub may have made a mistake in manoeuvring due to insufficient training of the crew
- the sub was involved in working-up training after a prolonged period of "inspections" [and Pete would guess maintenance/overhaul] prior to returning to full operations
- the Japanese Navy will be confirming this training status and "whether the prescribed ship manoeuvring methods were thoroughly implemented".
- the sub is in the port of Kochi [which seems to be first available port for safety rather than a regular Japanese Naval Base?]
- a ship accident investigator of the Japan Transport Safety Board began an official investigation, at Kobi, on January 10.
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JIVE'S VIDEO
3. Jive Turkey's Sub Brief video, uploaded Feb 10, 2021, here and below is very informative:
1:20 - the sub ascended in a very busy shipping lane area. [perhaps not a good working-up training area?]
1:50 - had to surface in that area before getting into overly shallow water [as shallows bad for sonar use and dangerous to stay submerged as you may hit seafloor]
= the sub took too long to get to periscope depth to get out of the way [again a training standard issue]
and
= there could have been a very strong [and shallow] thermal layer but Jive doesn't think so.