WI Japan Tried a Blockship at Pearl Harbor ?

robdab2

Banned
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 ?
 
First a beating on the IJN minisubs...

The only accomplishment in OTL at Pearl was negative, in that they were so useless that they didn't even do enough to trigger an alert before the IJN launched the first strikes, which wouldn't have done Japan any good at all.

Even assuming the minisubs are able to mob the USS Ward, which also requires the IJN's senior officers to realize the minisubs are virtually useless except in overwhelming force, not to mention the minor detail of naval artillery and major explosions being certain to alert everyone, if the destroyer gets off a radio message and then reports that they are under attack then the IJN may have just forfeited surprise over a single antique destroyer.

Whether the transport could make it in is another matter but it isn't likely to make much difference. Given the engineer units on the spot a single ships isn't going to stay blocking anything for very long.
 
Gah!!! 4 three times! Shi, shi, shi! Die-die-die!

The best the minisubs can do is ram the USS Ward. A better scenario would be the Nevada. That would cause some trouble.
 
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.
-- 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 ?

First. Ward is hit by silent torpedoes? You dont suppose people will notice a destroying going BOOOOOM when she is hit?(i have been waiting to write that:))

Second: And after they have shot a few times at USS Nevada they are out of torpedoes. What happens then?

Three: Wouldnt the yanks call a red alert and have AA manned and airplanes getting ready for combat/in air when the japs arrive?
 
robdab, why do you and Glenn keep trying to spam your ridiculous alt-hist notions at various websites? You were already told why it was completely unworkable at tank-net and probably Warships1 as well.
 

CalBear

Moderator
Donor
Monthly Donor
So we are giving the American forces 30 minutes advance warning? Cool. Imagine how many water tight doors can be dogged down, gun crews emplaced, and planes launched in the mad panic that would follow the SINKING of the harbor guard destroyer. You might even get a few destroyers and a couple of cruisers underway, with most of the rest of the fleet's boilers lit off and providing power for pumps and the like. May even get half the Army AAA gun crews up and to their posts.

Is is reasonable to assume that, if the Americans, who were paranoid as hell about spying and sabotage, if not an actual massive air attack, might put an escort or two on any Japanese flagged vessel entering the 12 mile limit? Pearl did have ninety plus warships available for that kind of work. The Army might even decide to man a couple more shore battery emplacements

Finally, a couple questions-

How much sinking do you think a 17,000 ton 1928-30 construction civilian ship would require?

You do realize that Pearl Harbor and the civilian port of Honolulu are two distinct and separate locations, right?
 

robdab2

Banned
Lets get this party started ...

Gents, thanks for the replys, my responses follow below ...

Their only accomplishment in OTL at Pearl was negative ... - I know, which is why I couldn't see any harm in changing their orders in my scenario.

... not to mention the minor detail of naval artillery and major explosions being certain to alert everyone ... - Historically Ward, which gateguarded some 5 nmiles out from shore, fired her gun at one minisub at about 0645 (putting a round thru the sub's conning tower base) and sank same with a full pattern depthcharge attack (set for 100' depth) and later on at 0703 depthcharged another (the jury is still out on Ward actually sinking that second minisub AFAIK). A USN PBY also contributed some loud exploding depthcharges against Ward's first minisub. And still the American defenders of Oahu were not alerted prior to KB bombs falling at0755, over an hour and 10 minutes later.

You need to remember that prior to Dec.7'41 much of Hawaii was used as US military training areas. Constant alerts, war warnings and drills (often with live ammo) leading up to the PH attack had lulled most of Oahu's population into ignoring the sound of explosions. Readings about the beginning of the Japanese attack on Oahu reveals many, many accounts of the population there still not believing that the Japanese attack was real, even as they watched flak exploding and bombs falling in the distance.

... if the destroyer gets off a radio message ... - Historically USS Ward sent not one but two radio reports of her attack on the first minisub, at 0653, one hour and two minutes before the KB's bombs started falling on Pearl Harbor. Kimmel and Bloch were notified at about 0712 but Bloch did nothing as he was told that Kimmel (his superior) was already informed. Kimmel did nothing except to ask for confirmation of Ward's attack (in fairness it must be said that there had been over a dozen submarine "false alarms" over the three months previous). Nobody bothered to inform the US Army or the USAAF, some 43 minutes prior to the Japanese bombs falling.

Given the engineer units on the spot a single ships isn't going to stay blocking anything for very long. - Please define your estimation of "very long" ? The Japanese couldn't have known it but imagine if Enterprise had not been able to enter a still burning PH on the very next night, Dec.8'41, to re-fuel ? Her only other source of fuel (assuming that Honolulu Harbor's fuel tanks and most of the wooden built City of Honolulu were burning after a 3rd KB strike - please see further discussion below) was the old and slow USN fleet oiler USS Neches then located some 1,200 nmiles to the NE of Hawaii. On the far side of a picket line of Japanese fleet submarines in point of fact. Enterprise and her TF didn't have enough fuel to reach her and so would have had to drift while she plodded in at her absolute maximum of 10.7 knots. A bad fallback plan indeed with some 30 IJN submarines historically participating in the PH attack and the KB still nearby (but withdrawing to the north).

Remember also that Tatuta Maru's bottoms would be well and truely blown out by the numerous scuttling charges (the Japanese maritime engineers would have placed them, probably with some boobytraps remaining, so as to make her speedy removal as difficult as was possible) so it wouldn't just be a simple matter of closing a seacock or two and pumping in compressed air to refloat her. It would take much slow hardhat diver work, in dirty and zero visibility harbor waters (full of sharp metal slivers, sewage, oil, human body parts and sharks, no doubt). All at a time when the few hardhat divers available on Oahu were very busy rescueing US sailors trapped inside overturned Pacific Fleet battleships. A quick removal ? I'd doubt it.

The Tatuta Maru's almost 17,000 ton sunken hull would stil be projecting some 40' above the water level and would be sitting in the mud some 45' below. Even blowing her up would take weeks since the Japanese minisubs might keep US vessels away from her for the first several days. And blowing her up would leave large pieces of debris scattered over the bottom of the entrance channel that varied between 40' and 45' in depth. Enterprise drew some 29' and her screws and rudder(s?) would not benefit at all from being dragged over Tatuta Maru's steel hull debris. Did I mention a Japanese mine or two ?

In answer to, "Whether the transport could make it in is another matter but it isn't likely to make much difference." - I failed to indicate in my scenario proposal, the underlying reason for any Japanese blockship attempt on Pearl Harbor. That being to combine such with an attack on the four largest fuel tankfarms on Oahu. Those that I refer to as the East PH, West PH, Ford Island (holding easily ignited avgas) and Honolulu Harbor tankfarms. This, of course, is a major POD from the historical timeline which requires a huge adjustment to the though processes of much of the IJN's high command staff. Which I agree, was extremely unlikely to occur historically. I didn't want discussion of that non-historical event to prejudice a fair blockship discussion.

But, imagine if you would, the effects of a 'lake' of blazing fuel inside of Pearl Harbor on the USN's Pacific Fleet now blocked therein ? In addition to the surface warships, the USN would loose 3 submarines and more importantly, the USS Neosho and the USS Ramapo, 2 of the only 4 underway re-fueling capable fleet oilers assigned to the US Pacific Fleet on Dec.7'41. Seven more tired and old USN tankers were assigned to that fleet but none of them could re-fuel a USN warship while underway. A serious drawback in the stormy wintertime Pacific Ocean.

Nimitz later testified that he needed 74 underway capable fleet oilers to carry the war to Japan so imagine the restrictions to his operational capabilities had he been reduced to just 2 instead of the 4 UW capable oilers that he had historically ? Sure, more could be transfered in from the US Atlantic Fleet, with consequent reductions to its operational capabilties. Such a trans-ocean shift thru the Panama Canal would have taken a few months, under the watchful periscopes of several IJN fleet submarines, I'm sure. And at a time when the historical 1942 German U-boat campaign against Allied tankers was just getting started in the Atlantic and Caribbean.

Calbear, you wrote,

"So we are giving the American forces 30 minutes advance warning? Cool." As I have responded above, historically the US defenders of Oahu were given 70 minutes warning by USS Ward but did nothing useful with that time. And the Opana Point radar warning at 0702 didn't get anywhere by 0755, some 53 minutes later, did it ? In light of that historical blundering, what help would my suggested reduction to just 30 minutes of warning have been to the US defenders of Oahu ?

Is is reasonable to assume that, if the Americans, who were paranoid as hell about spying and sabotage, if not an actual massive air attack, might put an escort or two on any Japanese flagged vessel entering the 12 mile limit? Pearl did have ninety plus warships available for that kind of work. - True enough yet historically they didn't do so for the first three repatriation liners that came thru Honolulu from Japan, the NYK's Tatuta Maru on October 22'41, the Nitta Maru on October 22'41 and the Taiyo Maru on November 1'41. History records that 3 Japanese agents were inded present on at least one of the three yet they were not detected and gathered much useful intel for the upcoming PH attacks.

Hindsight is easy I'd guess.

The Army might even decide to man a couple more shore battery emplacements. - Possibly but I've found nothing to suggest that such was done historically. In fact, Short's sworn testimony to at least two of the various Pearl Harbor Inquiries was that he didn't even order the manning of his 100+ Oahu mountaintop coastal artillery observation and fire control bunkers, despite the November 27'41 war warning message from Washington. The very troops supposed to be guarding Oahu from seaborne attack were not even ordered to their watch stations by their commander on that infamous day. Paranoid or rather, asleep at the wheel ? You tell me.

This suggests that the US Army command on Hawaii was paranoid about spying and sabotage by imaginary "fifth coulumnists" already on Oahu, not about the external arrival of same. Short expected Kimmel to warn him of any approaching military threat while he defended the Pacific Fleet against any attacks on its ships in port by sabateurs etc. I'd doubt that anybody on Oahu paid much attention at all to a Japanese cargo-liner visit already pre-approved by Washington. I believe it was Prange who details that local FBI agents did not even board the Taiyo Maru when she visited the Port of Honolulu, prefering to tail the US citizen passengers (of Japanese origin) who debarked there, instead.

How much sinking do you think a 17,000 ton 1928-30 construction civilian ship would require? - More than just 2x3" guns could provide in the time it took her to cover 5 nmiles at 21 knots - that being only about 14 minutes of confusion I'd imagine. I'd included a couple of hidden guns on the Tatuta Maru in the probably futile hope that some return fire might at least distract the US examination battery's 3" gunners. But I admit that it would be hard for the well drilled Americans to miss very often. Perhaps a KB Zero or two might be directed to strafe the open topped examination battery located within Fort Kamehameha ? Or is that too much hindsight ? Perhaps smoke might have been used to reduce the gunner's visibilty for the short time needed ? Back to the referenc books ...

Historically the British auxiliary cruiser (an old 6" armed civilian liner) "Jervis Bay" resisted numerous German battlecruiser 11" hits for some 2.5 hours before slipping under. And please, as I've already mentioned, remember that the Japanese would want Tatuta Maru to sink. I just don't think that only 2x3" guns would have the stopping power to overcome that high speed momentum of 17,000 tons. A picture of her sister, the Asama Maru, can be viewed at http://www.west-point.org/family/japanese-pow/PhotoFile/Asama_maru.jpg She and her sister were large vessels, for that time.

Ward's torpedo tubes did worry me but I believe that I have suggested a reasonable counter to Outerbridge's (he was one of the very few Americans actually aware and awake on that morning) probably aggressive use of them.

You do realize that Pearl Harbor and the civilian port of Honolulu are two distinct and separate locations, right? - Yes, I do. Just a short 5 nmiles apart IIRC. I had thought that my line,"- The Tatuta Maru then acelerates to her maximum speed and charges the PH entrance channel instead of moving eastwards towards Honolulu Harbor." in my thread opening post would have illustrated that clearly enough but now, it seems not.

What have I typed that makes you think otherwise ? The Pearl Harbor entrance channel was the subject of a US government 'restricted military area' order for several years prior to Dec.7'41, which was enforced 24/7 by gateguard US warship(s) like the USS Ward.

Honolulu's Harbor did not receive the same degree of protection until a few days post-December 7.

Is there a point to your question ?
 
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CalBear

Moderator
Donor
Monthly Donor
...
Calbear, you wrote,

"So we are giving the American forces 30 minutes advance warning? Cool." As I have responded above, historically the US defenders of Oahu were given 70 minutes warning by USS Ward but did nothing useful with that time. And the Opana Point radar warning at 0702 didn't get anywhere by 0755, some 53 minutes later, did it ? In light of that historical blundering, what help would my suggested reduction to just 30 minutes of warning have been to the US defenders of Oahu ?

Is is reasonable to assume that, if the Americans, who were paranoid as hell about spying and sabotage, if not an actual massive air attack, might put an escort or two on any Japanese flagged vessel entering the 12 mile limit? Pearl did have ninety plus warships available for that kind of work. - True enough yet historically they didn't do so for the first three repatriation liners that came thru Honolulu from Japan, the NYK's Tatuta Maru on October 22'41, the Nita Maru on October 22'41 and the Taiyo Mari on November 1'41. History records that 3 Japanese agents were inded present on at least one of the three yet they were not detected and gathered much useful intel for the upcoming PH attacks.

Hindsight is easy I'd guess.

The Army might even decide to man a couple more shore battery emplacements. - Possibly but I've found nothing to suggest that such was done historically. In fact, Short's sworn testimony to at least two of the various Pearl Harbor Inquiries was that he didn't even order the manning of his 100+ Oahu mountaintop coastal artillery observation and fire control bunkers, despite the November 27'41 war warning message from Washington. The very troops supposed to be guarding Oahu from seaborne attack were not even ordered to their watch stations by their commander on that infamous day. Paranoid or rather, asleep at the wheel ? You tell me.

This suggests that the US Army command on Hawaii was paranoid about spying and sabotage by imaginary "fifth coulumnists" already on Oahu, not about the external arrival of same. Short expected Kimmel to warn him of any approaching military threat while he defended the Pacific Fleet against any attacks on its ships in port by sabateurs etc. I'd doubt that anybody on Oahu paid much attention at all to a Japanese cargo-liner visit already pre-approved by Washington. I believe it was Prange who details that local FBI agents did not even board the Taiyo Maru when she visited the Port of Honolulu, prefering to tail the US citizen passengers (of Japanese origin) who debarked there, instead.

How much sinking do you think a 17,000 ton 1928-30 construction civilian ship would require? - More than just 2x3" guns could provide in the time it took her to cover 5 nmiles at 21 knots - that being only about 14 minutes of confusion I'd imagine. I'd included a couple of hidden guns on the Tatuta Maru in the probably futile hope that some return fire might at least distract the US examination battery's 3" gunners. But I admit that it would be hard for the well drilled Americans to miss very often. Perhaps a KB Zero or two might be directed to strafe the open topped examination battery located within Fort Kamehameha ? Or is that too much hindsight ? Perhaps smoke might have been used to reduce the gunner's visibilty for the short time needed ? Back to the referenc books ...

Historically the British auxiliary cruiser (an old 6" armed civilian liner) "Jervis Bay" resisted numerous German battlecruiser 11" hits for some 2.5 hours before slipping under. And please, as I've already mentioned, remember that the Japanese would want Tatuta Maru to sink. I just don't think that only 2x3" guns would have the stopping power to overcome that high speed momentum of 17,000 tons. A picture of her sister, the Asama Maru, can be viewed at http://www.west-point.org/family/japanese-pow/PhotoFile/Asama_maru.jpg She and her sister were large vessels, for that time.

Ward's torpedo tubes did worry me but I believe that I have suggested a reasonable counter to Outerbridge's (he was one of the very few Americans actually aware and awake on that morning) probably aggressive use of them.

You do realize that Pearl Harbor and the civilian port of Honolulu are two distinct and separate locations, right? - Yes, I do. Just a short 5 nmiles apart IIRC. I had thought that my line,"- The Tatuta Maru then acelerates to her maximum speed and charges the PH entrance channel instead of moving eastwards towards Honolulu Harbor." in my thread opening post would have illustrated that clearly enough but now, it seems not.

What have I typed that makes you think otherwise ? The Pearl Harbor entrance channel was the subject of a US government 'restricted military area' order for several years prior to Dec.7'41, which was enforced 24/7 by gateguard US warship(s) like the USS Ward.

Honolulu's Harbor did not receive the same degree of protection until a few days post-December 7.

Is there a point to your question ?

Yes there is. It is made clear by your response. You have endeavored to create a POD that has no basis in any sort of reality, I was mainly making sure that it was intentional rather than an honest error.

I can now answer your original question with greater clarity.

As posited this is both a extremely low probability event and a significant departure from the Japanese strategic plan, one that would have reduced the American losses at Pearl Harbor while notably increasing JNAF losses had it occured. It has virtually no hope of succeding and would also not prevent many American units from exiting the harbor even if successul, particularly submarines and destroyers. The loss of Pearl for the 30 or so days that, even if completely successful, this action would cause would have no impact on naval operations, as heavy units could, temporarily, refuel at Lahaina Roads, an anchorage off Maui (in OTL, the Japanese had hoped that this anchorage would be in use by the USN, as the water was quite deep, making the attack easier and salvage of sunken ships impossible).

As to the use of Ko-Hyoteki Type A Midget subs to mob the Ward, this is, at best, very unlikely. The boats had very short range (at 19 knots, the speed needed to "mob" a destroyer patrolling at 15 knots range was under 20 miles), poor manueverability, and there is no sign that the Type 97 torpedo or the Type A targeting system were capable of hitting a destroyer moving at 15, much less 30, knots. In actual use, 19 knots would make a successful "wolfpack" attack nearly impossible. It is worth noting that (IIRC) at least one of the Type A boats couldn't manuever sufficiently to make the harbor entrance due to cross currents.

As to possible effects- JNAF losses are seriously increased, up to 80 - 100 aircraft over the target and a total airframe loss (including the difficulties encountered with the return landing, and "mission kills" beyond repair) between 240 and 300 (OTL's total was 100) causing relays in use of Kido Butai decks in support of other December 1941 actions (notably Wake Island & Rabaul). American losses are also likely reduced, both in aircraft destroyed and ships (especially USS California & possibly USS Oklahoma) lost with 30-45 minutes warning given by the aggressive Japanese actions.

Overall, this sort of act would greatly damage the tactical surprise the JNAF enjoyed at Pearl for virtually no strategic advantage, and likely a serious short term strategic handicap.
 
Sinking a blockship is easier said than done. First off I am weary of the top speed of the Tatuta Maru and knowing the distance between Honolulu Harbor and Pearl Harbor from having lived in Honolulu I doubt that it would have gotten that close without being intercepted and challenged.

Its doubtful that any booby traps would have been added aboard since the Japanese would have thought that eventually they may have had to remove the hulk.

I've got to admit that the element of surprise is entirely loss and would just consider that US forces are alerted and are at a higher degree of awareness. There is no way such an action can be considered anything but a hostile act. The usefulness of the midget subs described as minimal, unless it can be determined that one had penetrated the harbor before the attack.

"- 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."

Targets, that is all you have provided for US forces.
 
The idea is fundamentally flawed. All the IJN needs to do is to launch the third strike against the oil tank farms for far greater results, crippling the US Pacific fleet for six months or more.

The ability of US engineers to destroy obstacles in remarkably short order in WWII is a proven fact and the worthlessness of the minisubs is also. Given that the engineers don't even need to dive but can start hauling most of the tanker off with existing shipping, explosives and acetylene torches it won't take long at all.

And the IJN thought the Enterprise was already in Pearl Harbor, as it was scheduled to be, so they certainly aren't wondering about where else it might berth.
 

robdab2

Banned
Pearl Harbor Blockship

CalBear,

I am somewhat perplexed by your response. Perhaps I was not clear in indicating that my blockship proposal was intended to be ADDED to the historical IJN effort at PH, along with a 3rd raid as proposed in another thread on this site, not to replace the entire Japanese air raid ?

It has virtually no hope of succeding and would also not prevent many American units from exiting the harbor even if successul, particularly submarines and destroyers - And neither did the historical Japanese raid prevent the lighter USN warships from exiting in any way. My scenario, when combined with a 3rd wave air attack against the fuel tankfarms & fleet oilers inside of PH, would have robbed those short ranged lighter warships of the fuel needed to go much of anywhere else.

... this action would cause would have no impact on naval operations, as heavy units could, temporarily, refuel at Lahaina Roads, an anchorage off Maui (in OTL, the Japanese had hoped that this anchorage would be in use by the USN, as the water was quite deep, making the attack easier and salvage of sunken ships impossible). -Yes the Japanese checked Lahania Roads with two I-boats and a cruiser floatplane prior to the start of the 0755 air attacks, just in case any USN heavy units missing from PH had anchored there but I must point out that Lahania Roads was a deep water open anchorage area only. AFAIK there were no large scale fuel storage or handling facilities located there and thus no fuel for the USN's Pacific Fleet units, large or small. That roadstead was completely open to the sea on two sides, too deep for existing US anti-torpedo and anti-submarine nettings (which weren't stocked in quantity on Oahu in Dec.1941 anyway) and more than deep enough for the dropping of regular aerial IJN torpedoes. How could the US Pacific Fleet be safe there, even temporarily ?

As to the use of Ko-Hyoteki Type A Midget subs to mob the Ward, this is, at best, very unlikely. The boats had very short range (at 19 knots, the speed needed to "mob" a destroyer patrolling at 15 knots range was under 20 miles), poor manueverability, and there is no sign that the Type 97 torpedo or the Type A targeting system were capable of hitting a destroyer moving at 15, much less 30, knots. - I believe that my scenario clearly indicated that Ward would be attacked as she slowed to approach Tatuta Maru in order to launch a small boat for the purposes on transfering an inspection team and a (Honolulu) harbor pilot. Small boats aren't usually launched from destroyers travelling at even 15 knots, let alone 30 (if the old Ward could still get to that high a top speed). Did you even read my scenario ?

It is worth noting that (IIRC) at least one of the Type A boats couldn't manuever sufficiently to make the harbor entrance due to cross currents. - Not due to cross currents at all. It is true that one of the five minisubs suffered an inertial compass failure and as a result had great difficulty navigating towards the narrow Pearl Harbor entrance channel while submerged and otherwise blind.

My scenario specified the use of all 5 minisubs to "mob" the Ward just so that a technical failure in one or two of the minisubs would not result in total mission failure. Since Yoshikawa could have easily reported the location of the gateguard destroyer's '2 mile x 2 mile patrol box' I don't see why you insist that any of the minisubs would have to devote much effort to positioning themselves in nearby ambush locations ? Once near to that known destroyer 'patrol box' each could have stayed stationary, periscope extended (with no wake due to no movement) until Ward slowly approached the Tatuta Maru.

As to possible effects- JNAF losses are seriously increased, up to 80 - 100 aircraft over the target and a total airframe loss (including the difficulties encountered with the return landing, and "mission kills" beyond repair) between 240 and 300 (OTL's total was 100) causing relays in use of Kido Butai decks in support of other December 1941 actions (notably Wake Island & Rabaul). American losses are also likely reduced, both in aircraft destroyed and ships (especially USS California & possibly USS Oklahoma) lost with 30-45 minutes warning given by the aggressive Japanese actions. - I can only assume that you attribute all of this to the loss of surprise that you feel would be the result of a blockship mission used instead of the historical minisub orders ? I notice that you do not respond at all to my examples of the US defenders not picking up on the historical warnings that did occur prior to 0755 ? I am disappointed.

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David, you wrote,

...knowing the distance between Honolulu Harbor and Pearl Harbor from having lived in Honolulu I doubt that it would have gotten that close without being intercepted and challenged. - By arriving from the SW the US government approved and expected Tatuta Maru would normally have first passed across the entrance to the PH ship channel before nearing Honolulu and thus would have been first intercepted by the Ward patrolling some 5 nmiles offshore. A small US Coast Guard launch based inside of Honolulu Harbor usually transfered harbor pilots to commercial vessels entering there but her commercial services did not begin until 0900 each day so Ward would have done that 0700 task for a state approved naval visit.

Its doubtful that any booby traps would have been added aboard since the Japanese would have thought that eventually they may have had to remove the hulk. - Only if you believe that the Japanese could have successfully invaded and then held Oahu ??

I've got to admit that the element of surprise is entirely loss ... - Why do you feel that to be the most likely outcome ? Would just one or two torpdeo hits on Ward have been any more noticeable from 5 nmiles away than were the historical 12 cannon shots and 6+6+2=14 depthcharge explosions ? And in my scenario there would be much less time for any warning to filter it's way up the chain of command than was the historical case.

There is no way such an action can be considered anything but a hostile act. - True but neither can attempting to sneak at least two minisubs into PH or sending nearly 200 KB attack planes against Oahu from the north. Neither is at all a "friendly act".

... unless it can be determined that one had penetrated the harbor before the attack. - Historically one minisub was sunk and later salvaged well inside of the inner harbor at Pearl. AFAIK only one of the 5 minisubs remains unaccounted for so maybe two made it inside ... ?

Targets, that is all you have provided for US forces. - Whether lurking in the shipping channel or skulking around inside of PH, all of the five Japanese minisubs were targets for the Americans.

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Grimm,

All the IJN needs to do is to launch the third strike against the oil tank farms for far greater results, crippling the US Pacific fleet for six months or more.- Oh I certainly agree and suggest that as Bloch, Kimmel, KIng and Nimitz all testified, it would have been two years of delay, not just 6 months, had those PH fuel tanks been destroyed.

My purpose for suggesting a blockship is really to prevent the sortie of any USN battleships or heavy cruisers that might have been missed by the KB's 1st and 2nd wave air raids. If Nagumo really intended to "stick around" for a 3rd strike he would rest easier knownig that most of the USN's Pacific Fleet was bottled-up inside (a flaming) PH.

Given that the engineers don't even need to dive but can start hauling most of the tanker off with existing shipping, explosives and acetylene torches it won't take long at all. - How is it that you propose to cut up the 40'-45' deep submerged portions of a 17,000 ton cargo liner (Tatuta Maru was never a tanker) with hand held acetylene torches if you don't intend to use divers ? How/where will you place your explosives without sending in divers who must be hardhat types since AFAIK the scuba system had yet to be invented in 1941/2.

Perhaps you intend to import pearl-diving (pun intended) women from the Japanese home islands ... doh, that won't work because you are now at war with Japan. LOL.
 

CalBear

Moderator
Donor
Monthly Donor
Without devoting any more time than necessary to what is rapidly becoming an ASB scenario.

Pearl Harbor was attacked to destroy the Battle Squadron and hopefully the carriers. The carriers were missed, but the battlefleet was seriously damaged, to the point that it was a non-factor until Leyte. This makes the action to block the channel an utter waste of time since light units and submarines can exit the harbor even of the blockship was perfectly placed (one of the more difficult feats in naval warfare)

Lahaina Roads was indeed just an anchorage, however, that would be the only reason it would be needed. The only ships that would require fueling at the Roads would be the carriers themselves, along with, perhaps, the heavy cruisers. This could be accomplished from fleet oilers in well under 12 hours, meaning any supposed I-Boat attack would have to take place in daylight in the presence of considerable land based air cover, destroyers, and even temporary netting from boom tenders (an unlikely need, but a technically feasible one).

As far as the American ignoring the pre-attack indicators. you are absoultely correct that the U.S. command was criminally negligent in this regard. Nevertheless, ignoring a report by a destroyer that it had engaged an enemy sub (something that HAD happened in the recent past) and ignoring the duty destroyer being blown out of the water, immediately followed by a Japanese flagged civilian ship attempting to block the harbor entrance (something that was obviously a unique event) is entirely something else.

The Japanese were just about as lucky as possible at Pearl; much of that luck they manufactured by avoiding stunts that tipped their hand (although the Type A subs damn near screwed it up for all concerned on the Japanese side). Adding this entirely useless element would endanger a year of planning, intense training, and all the luck the enterprise had already garnered. In short it is a rather foolish idea, one that any serious naval officer would reject out of hand (and the Imperial General Planning Staff was a very serious group indeed).

You are entitled to play with this as far as you like, however, all the effort in the world will not make a silk purse out of this sow's ear.
 

robdab2

Banned
Thats GGASB to you ...

... short for Giant Green Alien Space Bats.

CalBear,

Why the hostility ? With a name like "Alternate History Discussion: After 1900" I had assumed that this was the correct place to present a PH alt. scenario ? Was I mistaken ?

Your "The carriers were missed, but the battlefleet was seriously damaged, to the point that it was a non-factor until Leyte. This makes the action to block the channel an utter waste of time ..." is a hindsight type of arguement. The Japanese of Dec.6'41 could not know how well their next day's attack was going to come off and so might not have considered my scenario to be such a waste of time as you do, some 66 years later.

The only ships that would require fueling at the Roads would be the carriers themselves, along with, perhaps, the heavy cruisers. This could be accomplished from fleet oilers in well under 12 hours. - The only problem being that historically there were no other USN fleet oilers anywhere near Oahu on Dec.7'41 save Neosho, Ramapo and Neches. Please see http://www.ibiblio.org/pha/pha/misc/non-ph.html for a listing of the other Pacific Fleet oilers located on the US West Coast etc, some 2,400 nmiles to the east of Oahu. Where then is Enterprise going to get a belly full of fuel oil from on the night of Dec.8'41 ? Her 29' loaded draft prevents her from entering Honolulu Harbor's 27' dredged entrance channel to tap the civilian fuel tanks located therein and the one civilian tanker present there is fitted for the transfer of asphalt (for Oahu road and runway paving), not fuel oil. She's screwed, I think.

If Enterprise does find some fuel somewhere, she is fitted to re-fuel the heavy cruisers and destroyers of her own escort TF, herself.

... even temporary netting from boom tenders (an unlikely need, but a technically feasible one). - Save that http://www.navweaps.com/index_oob/OOB_WWII_Pacific/OOB_WWII_Pearl_Harbor.htm
does not list even a single boom tender as being present at PH on Dec.7'41. So actually, not technically feasible at all, for the several weeks that it would take a net tender (and deep enough nets) to arrive from the US West Coast.

Nevertheless, ignoring a report by a destroyer that it had engaged an enemy sub (something that HAD happened in the recent past) and ... - once again, I don't think that you have actually read my scenario. If not ordered to sneak into PH then none of the minisubs would have been spotted while attempting to tail the minesweeper Condor into PH, nor spotted while trying to follow USS Antares in either. Hence no reports to the PH harbormaster in my scenario, about engaging an enemy submarine. And kless potential of an early warning to Oahu's defenders.

I suppose that I could improve the scenario by specifying that Tatuta Maru be fitted with a low power, full spectrum radio jamming transmitter that an IJN techno-geek could use to block any radio transmissions from Ward after she had been torpedoed.

We know that day was a poor one for radio transmissions since the Washington attack warning message had to be sent to Oahu via telegram instead of by radio. Such poor conditions might have served to disguise the 1 hour long local use of a radio jammer, or not.

... ignoring the duty destroyer being blown out of the water, ... - from 5 or more miles away and who would have been likely to have been watching at 0700 anyway ? There certainly was no historical flood of civilian phonecalls after Ward fired 12 cannon shells and dropped 14 depthcharges on Dec.7'41. But then whether Ward blowing up will be noticed doesn't matter when a running gunbatle begins between the US 2x3" examination battery and the now charging Tatuta Maru.

... immediately followed by a Japanese flagged civilian ship attempting to block the harbor entrance (something that was obviously a unique event) is entirely something else. - True enough but how long would it have taken an alert message to filter around the US fleet and army if the cargo-liner didn't begin her charge until 0730 ?

... (although the Type A subs damn near screwed it up for all concerned on the Japanese side). - Which is why I thought it best to give them a new mission far less likely to draw US attention to them, so early in the day.

...all the luck the enterprise had already garnered ... - nice pun !

You are entitled to play with this as far as you like, ... - Thanks but I wasn't aware that I needed your permision to do so ? Did I miss a memo or something ? LOL.
 

robdab2

Banned
Minor Corrections ...

... to my just previous posting ...

I've just found a 1939 map of Honolulu Harbor which indicates a minimum dredged depth of 38' there, not the 27' that I previously reported. So, Enterprise could indeed have slipped in there for fuel, if necessary.

The distance between San Francisco and Honolulu is approximately 2,100 nautical miles, or 2,400 statute miles, not the 2,400 nautical miles that I just previously listed.
 
Robdab, why don't you just skip the "Look, I'm so innocent" act and simply go straight to your opium dream alt-hist plan of a Japanese invasion of Hawaii on Dec 7th?
 

robdab2

Banned
Pearl Harbor Blockship

Mote,

What is it that has you so upset here ? Is this not a AH discussion board where ideas can be posted and then discussed ? Has someone appointed you to a board censor position that you feel you are not using enough ?

I've not proposed an invasion of Oahu (and David S. Poepoe did present me with a perfect opportunity to do so) because I'm trying to flush out informed, detailed objections/comments about the PH blockship scenario that I have proposed with this thread. Sadly for me, so far all that I'm getting is vague generalities that I believe I have managed to refute, point by point.

I had been told that several "Hawaii experts" could be found here but I can only surmize that my blockship scenario proposal was not good enough to attract their attention/responses ? I may have to try again with a different topic, perhaps an invasion of Oahu one to keep you happy ?

I was expecting objections to the difficulties involved in co-ordinating to the minute the actions/locations of the Ward, the Tatuta Maru and the 5 minisubs, considering the presence of other interfereing US naval traffic proceeding in and out of the PH ship channel at that time of day but so far, no one has jumped on that one. I was also expecting objections based on the overhead transitting presence of as many as 4 USN PBYs headed out to search the Pacific Fleet training areas offshore of Honolulu for the presence of lurking submarines but no one here has yet twigged to that one either.

Perhaps you could post a novel objection/agreement of your own that doesn't just parrot CalBear's opinions or those from another thread ?

If you don't wish to participate in a discussion of this blockship scenario subject then please feel free to move on to another thread that you find more entertaining than this one.
 

CalBear

Moderator
Donor
Monthly Donor
Mote,

What is it that has you so upset here ? Is this not a AH discussion board where ideas can be posted and then discussed ? Has someone appointed you to a board censor position that you feel you are not using enough ?

I've not proposed an invasion of Oahu (and David S. Poepoe did present me with a perfect opportunity to do so) because I'm trying to flush out informed, detailed objections/comments about the PH blockship scenario that I have proposed with this thread. Sadly for me, so far all that I'm getting is vague generalities that I believe I have managed to refute, point by point.

I had been told that several "Hawaii experts" could be found here but I can only surmize that my blockship scenario proposal was not good enough to attract their attention/responses ? I may have to try again with a different topic, perhaps an invasion of Oahu one to keep you happy ?

I was expecting objections to the difficulties involved in co-ordinating to the minute the actions/locations of the Ward, the Tatuta Maru and the 5 minisubs, considering the presence of other interfereing US naval traffic proceeding in and out of the PH ship channel at that time of day but so far, no one has jumped on that one. I was also expecting objections based on the overhead transitting presence of as many as 4 USN PBYs headed out to search the Pacific Fleet training areas offshore of Honolulu for the presence of lurking submarines but no one here has yet twigged to that one either.

Perhaps you could post a novel objection/agreement of your own that doesn't just parrot CalBear's opinions or those from another thread ?

If you don't wish to participate in a discussion of this blockship scenario subject then please feel free to move on to another thread that you find more entertaining than this one.

PBY's would, as IOTL not have been effective in finding the Type A mini's. Not at night & Sunrise was around 07:00 on December 7th.

You may not be getting more responses since it is clear that you are wedded to this proposal outside of any justification or counter argument. That is certainly why I have stopped communicating, especially once you acknowledged that you had the dpeth of Honolulu harbor wrong & any heavy units could fuel there.
 
Mote,

What is it that has you so upset here ? Is this not a AH discussion board where ideas can be posted and then discussed ? Has someone appointed you to a board censor position that you feel you are not using enough ?

Because you have a habit of going from board to board posting the same stupid shit and ignoring what everyone else says.

I've not proposed an invasion of Oahu (and David S. Poepoe did present me with a perfect opportunity to do so) because I'm trying to flush out informed, detailed objections/comments about the PH blockship scenario that I have proposed with this thread. Sadly for me, so far all that I'm getting is vague generalities that I believe I have managed to refute, point by point.

Yeah, just like how you "just wanted some info on WWII IJN bombardment" over at Tank-Net?

Perhaps you could post a novel objection/agreement of your own that doesn't just parrot CalBear's opinions or those from another thread?

Why don't you actually listen to people's criticisms for once?
 

robdab2

Banned
CalBear,

That is certainly why I have stopped communicating, especially once you acknowledged that you had the dpeth of Honolulu harbor wrong & any heavy units could fuel there. - So let me be sure that I understand you correctly now ? You stopped communicating with me some 4-5 hours ago when I posted a depth correction that I had just discovered minutes before from a new (to me anyway) source ? Yet you just comunicated that fact to me, so which is it - we're talking or we're not talking ? I am confused.

And please explain your debating style to me ? Have you never discovered new information during the course of a debate ? In the persuit of truth and honesty, would you not post that new information, as soon as it was known, rather than continuing to deliberately deceive your verbal opponent ?

I note that you never disputed the dredged depth of Honolulu Harbor that I posted late yesterday. Did you even know it and can you provide a source for same ? And are you really sure that ANY heavy units could fuel therein ? Have you checked to see if any of the Pacific Fleet's battleships draw more than 38' ? Have you confirmed their width vs the width of BOTH of Honolulu Harbor's entrance channels and the depths/widths at it's 4 fueling piers ?

If my blockship gets into place then no Pacific Fleet heavies (save the missing carriers) will be able to leave Pearl Harbor anyway. And even better, when "my" Japanese were planning the blockship scenario surely they would have hoped to include at least two US carriers in the number of US warships trapped inside of PH, by it.

You may not be getting more responses since it is clear that you are wedded to this proposal outside of any justification or counter argument. - Because I have yet to read any good counter-arguments here. My scenario continues to look better and better, if 66 years of hindsight is not used.

And what if, as I mentioned in another post of this thread, a 3rd Japanese wave had just bombed those Honolulu Harbor fuel tanks ? Even worse for the US, what if those tanks are bombed when one of the missing carriers is trapped inside of that tiny harbor ? Or, what if a lurking Japanese minisub torpedoes a carrier as she slowly lines up on one of the narrow Honolulu Harbor entrances ? Keeping in mind too that an additional 5 full sized I-boats, the mother-ships of the 5 minisubs, still lurk in Mamala Bay awaiting targets of opportunity like a nice slow carrier. I-20 was assigned to patrol the sector between the entrance channel to Pearl Harbor and the approaches to Honolulu Harbor but the other 4 were still nearby.

-------------------------------------------------------------------------
Mote,

Because you have a habit of going from board to board posting the same stupid shit and ignoring what everyone else says. - And is this a crime that hurts anyone in anyway ? In point of fact I do indeed learn from responses and modify my ideas accordingly.

Yeah, just like how you "just wanted some info on WWII IJN bombardment" over at Tank-Net? - As of 5 minutes ago my Tank-Net thread has attracted some 490 posts and has been read 8,658 times, so somebody sure likes that topic even if you don't. I'm sorry that you don't feel that the world is revolving around you alone, in this case. Get over it. Sadly I never did get much hard data on Japanese shore bombardment doctrine/practise, either in China or during WW2 from that thread but the 'communication' has certainly covered much ground to the enlightenment of many (except you apparently).

Why don't you actually listen to people's criticisms for once? - Mostly because the majority of posters on these boards just type their (often mistaken) opinions WITHOUT benefit of listing their published (and verifyable) sources of information. My own research often shows their opinions to have been in error, often grossly. Yet I find just enough "gold", mixed in with the dust, to continue my exploration journey. With little result from posters such as yourself.
 
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I had been told that several "Hawaii experts" could be found here but I can only surmize that my blockship scenario proposal was not good enough to attract their attention/responses ? I may have to try again with a different topic, perhaps an invasion of Oahu one to keep you happy ?

I guess I should address this. I'm one of the resident 'Hawaii experts', but my strength is really 19th to early 20th century Hawaii. WWII and in particular the Attack on Pearl Harbor is just on the rim of my interests. Unless battleships are involved. I've lived in Honolulu for a good many years so I can at least visualize distances and areas in discussion.
 
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