Not sure how JDS dealt with this, but Kanmon for us was similar to Shimonoseki in that we had a pilot on board - it could very well have been a failure on a pilot’s fault - though final responsibility still lies with the CO it would mitigate if the pilot had control.
I forgot all about the possibility of a pilot. You’re right-we would have had a pilot but I don’t know either how JMSDF handles the straits. It is the shortest route between Sasebo and Kure so they may use it quite a bit-or not.