A thousand pardons if this has been asked before but reading my copy of Grodon Prange's book, "At Dawn We Slept" has suggested the following scenario to me and I'd like (polite) comments about its viability ...
On page #444 Prange presents the historical deception voyage of the cargo-liner Tatuta (also spelled Tatsuta) Maru which was approved by the US government to pass thru Honolulu on Dec.9'41 as the fourth repatriation voyage permitted between America and Japan since the US merchant shipping embargo had been put in place. Both USAAF and USN recon flights out of Oahu would expect to spot her and watch her approach.
In reality she became a valuable fast troopship for Japan's war effort but I think this mission to be worth the price.
It occurs to me that her 17,000 tons and 21 knot speed would have made her an excellent blockship. Her 584' length would span most of the 700' dredged width of the PH entrance channel and her 85' keel to upper deck height would not submerge in that 45' deep channel, either.
As my first small POD, it would have been a simple matter to advance her historical scheduled Dec.9'41 arrival date to say, 0700 on Dec.7'41, instead.
After she was secretly fitted out with additional anchors, 2x4" guns (hidden), a secondary steering room deep inside her hull and numerous scuttling charges designed and placed so as to quickly sink her on an even keel.
Yoshikawa, the resident spy inside Japan's Honolulu Consulate would have reported that each morning a pair of US minesweepers did a sweep of the entire Pearl Harbor entrancwe channel which left the anti-submarine nets open between 0500 and 0830. He would have also reported, with the aid of the Consulate's telescope that the American PH gateguard destroyer followed the same 15 knot, 2 mile by 2 mile patrol box every day.
My second POD from the historic timeline involves ordering the 5 Japanese minisubs to torpedo that gateguard destroyer, the USS Ward, instead of penetrating into PH as they were ordered historically.
Research in Osprey's "Defenses of Pearl Harbor and Oahu 1907-50" by Williford & McGovern (and elsewhere) indicates that only one examination battery of 2x3" guns was manned and on duty that morning to cover the PH entrance channel. Another battery of 2x6" US coastal artillery guns was on one hour standby alert also.
All the rest of Oahu's 16", 14", 12" and 8" coastal artillery was neatly locked up and unmanned except for a few overnight anti-sabotage sentries on this average, peacetime Saturday liberty night.
I'd imagine that you can guess the rest of my scenario:
-Tatuta Maru approaches the south shore of Oahu at 0700 and is recognized by USS Ward which was expecting her arrival.
- As Ward slows to dispatch an inspection team and harbor pilot she is torpedoed by one or more of the 5 lurking Japanese minisubs. Hit at least twice, her guns, torpedo tubes and radio are no longer a threat to the Tatuta Maru by 0730.
- The Tatuta Maru then acelerates to her maximum speed and charges the PH entrance channel instead of moving eastwards towards Honolulu Harbor.
- At some point she and the US examination battery begin to exchange gunfire but the US 2x3" cannot hope to stop the charging 17,000 ton cargoliner.
- Her bridge is targeted by the US gunners but her recent secondary steering position maintains rudder control as she passe thru the still open US anti-submarine nets (2) at 0745.
- Her small crew swing her perpendicular to the channel and drop her numerous anchors so that her blocking position is held as she settles. Which she quickly does after the scuttling charges are fired at 0800. The 2x3" US guns continue to punch holes in her but the objective is for her to sink afterall.
- As a final step, any of the Japanese minisubs still carrying torpedoes position themselves around her sunken hull so as to be able to finish any US warships which attempts to clear the blockship. More corks in the botleneck.
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So gents, what is your verdict ?