"The Biggest Boondoggle"???

[Lesforan]

Gee, Chuck,

From reading this Forum over the past several years I got the impression that "Shattered Sword" was so good and so accurate it negated all previous works' conclusions on The Battle of Midway. Nice to see that opinion is not universal.
I have not read the book, but the part about the plastic kit instructions being used as a reference source for an historical work is quite a revelation to me. (I was treated rather roughly by a professor in my freshman college year for attempting this very stunt in 1968. He was as impressed by the tactic as you are.)

Maybe this book is not inspired scripture after all. Maybe some conclusions about this battle I reached by reading other authors is not heresy after all. This (could) change everything.

[Timmy C]

Chuck, if you are talking about the picture on page 118 with the note "Adapted from Hasegawa", have you ever thought that "Hasegawa" might refer not to the model company, but rather, to Hasegawa Toichi, author of Japanese Aircraft Carriers? Though the pictures are not given a reference note (that I can see), the reference to Toichi can be found for note 7 of page 119.

[chuck]

No, I have not thought of that. I have to go back and read it again.

[bengtsson]

What you said in your last post is right on the money Walt. The USN has been more than impressed by foreign Diesel boat's abilities. You are also right that they have more of a local defense role. They are not about chasing a CV group around the high seas, that's a nuclear attack boat's role. The defence of areas of probable CV operation is their proper role. With their sonar, they can know pretty well what is going on up top. Their detection ranges are huge, allowing a silent approach to good ambush positions. Of course it isn't a sure bet every time. But sooner or later they will be able to get into a good attack position. They can choose either a torpedo attack if that presents itself, or a launch of anti shipping missiles.
It was common knowledge amoung sonarmen, that the hardest thing to detect was the Diesel Boat on batteries. And these modern boats aren't type VII Uboats. Things have improved alot, and no submariner or surface sonar technician I ever knew looked down the Diesel Boat.

Bob B.

[MichelB]

In light of this discussion, wouldn't we love to see some info on the USS America sinkex? I can imagine they put some torpedoes under her keel... never will happen, I can imagine that info being as classified as it gets.

[chuck]

In light of this discussion, wouldn't we love to see some info on the USS America sinkex? I can imagine they put some torpedoes under her keel... never will happen, I can imagine that info being as classified as it gets.

It will eventually come out after its relevance is passed, and it may even come out much sooner than that if it can be used to publicly support certain naval construction policy.

BTW, torpedo under the keel is not unknown from WWII. Yamato, for example, took a few under her keel when she was listing and thus presenting her bottom at an angle to incoming torpedoes. It exacerbated her flooding, but did not break her back, nor cripple her propulsion. The hull of modern carriers are significantly wider than Yamato's, and has much deeper girder structure thanks to the integral flight deck. So I would guess a modern carrier's resistance to major structural failure would be very great and no mere 21" torpedo is going to break the back of a CVN.

As to the issue of bomb damage, that does illustrate a more serious vulnerability, which is relatively little ordinance might be needed to put an end to a carrier's flight deck operations. Certain the flight deck accidents that befell the USN several times during Vietnam war suggests that a carrier can be incapacitated for hours or even days by just a few explosions on deck. But here the issue is a little more hazy because:

1. It's not all together clear that ASM's that get through will actually hit the carrier's deck, Most may just make holes on the skin of the carrier's hull. It's not clear how much buffer there is on the carrier's hanger side, whether the hanger side has any armor protection at all, and whether impact by a typical ASM is likely to do a lot of damage inside the hanger. The carrier is a much bigger ship than any warship that actually took an ASM hit for real. So the story of the HMS Sheffield and USS Stark might give an all together misleading impression of just what might happen if a medium sized ASM hits a carrier.

2. It's not all together clear how effective are the electronic countermeasures. Just how many ASMs that find its way near a carrier will actually hit?

[Devin]

BTW, torpedo under the keel is not unknown from WWII. Yamato, for example, took a few under her keel when she was listing and thus presenting her bottom at an angle to incoming torpedoes. It exacerbated her flooding, but did not break her back, nor cripple her propulsion.

I would submit that those are not the same. Yamato took a torpedo IN her keel, not UNDER it. The difference is huge; akin to the difference between simply punching a two-by-four, or taking that same piece of wood and propping it up on two blocks and then punching it, as they do in karate demonstrations. The reason there is so much concern taken with keel blocks when a ship enters dry dock is that a ship's hull is not meant to be deprived of it's only support, the water underneath.

Now, how big of a warhead would you need to blow a "hole" in the water to buckle a carrier's hull? No idea, but it is indeed possible.

[chuck]

That might have been a significant distinction on a small ship, where the transient bubble from a torpedo explosion might replace water buoyancy over a signicient fraction of the hull. But I am not certain the transient air bubble formed by a torpedo explosion ever gets to be so large as to make it a significant distinction on a hull 42 meters wide. Considering WWII era torpedoes seem to destroy of battleship torpedo defense system in roughly 20 meter sections, I might guess that the transient air bubble of a torpedo warhead would be about 20 meters across. Also, under keel explosions, being deeper and subjected to greater water pressure, would produce smaller transient bubbles than torpedo warhead striking ship's sides. That will make it less than half as wide as a carrier hull, and replace perhaps 1/20 of the total water bouyancy under the ship's keel. I would not imagine that would hugely overload the hull girder. A carrier hull stuck in a deep trough between two waves is probably being bent by a much greater force than 1/15th of its normal buoyancy.

BTW, didn't the Tirpitz undergo several true underkeel explosions caused by mines deposited under her keel by British midget submarines? If I recall, those warheads were much bigger than typical torpedo warheads.