Sorry, but I must disagree. My readings indicate that the IJN minisubs used at PH only contained enough air to be good for about 4 hours of submerged operation UNLESS the compressed air bottles inside were slowly opened. These however could NOT be refilled by the minisub itself and so were for "one time" use during an actual attack. I think it lilkely that the OTL minisub following the USS Antares in the darkness had NOT accidentally breached at all but rather was running with her sail exposed and hatch open to replenish her internal air supply, just prior to entering the PH entrance channel fully submerged. Granted, another minisub DID indeed broach when she fired not just one but rather BOTH of her bow carried torpedos in rapid succession while deep within PH so I think them only difficult to control when firing torpedos, NOT during regular navigation. Sure there was. The three PBY inshore air patrol was a regular as clockwork 7 day a week air search flown counter-clockwise around Oahu from a Kaneohe NAS take-off at 0630 hours. By the time that my ATL blockship arrived off of Honolulu Harbor and the USS Ward was torpedoed by the IJN minisubs, that three plane patrol would already be 30-60 miles to the south of Honolulu checking the Pacific Fleet's usual exercise areas for any potential enemy submarines, before returning to Kaneohe NAS. Visible everyday from Japan's Honoilulu Consulate where Yoshikawa was based. Except that the 3 of them would already have left the Mamala Bay area, as they did everyday, about an hour before the Ward would be torpedoed and my ATL TatutA Maru would turn away from Honolulu Harbor in order to begin her intended scuttling run on the Pearl Harbor entrance channel.