Submersible Aircraft Carriers

as per the considered attack on the Panama Canal.

First, there are a number of separate side by side locks in the Panama Canal, the Gatun, Pedro Miguel and the Miraflores locks I remember by name. (I put that in for the guys who don't know there are multiple locks, side by side) But since they were "twinned" and each canal was "one way" until war time, even attempting to close one direction wouldn’t close the Canal per se.

Any of them could have been the "targets" of float-plane bombers or those carried by submarines later like the I-400s. but the planes would have to evade a number of air-defense stations, and the counter-air cables strung between the hill tops after 1938 (a number of US planes fell victim to them before the war). Then on either end of the thing there were substantial coastal batteries, and because of the fear of Axis sabotage by scuttling a ship, exploding one in the locks, bombing, or air-torpedo attack plans had been made for emergency closure of each lock and had anti-torpedo netting installed between each lock. As I understand the way the system worked with the net was it lowered when and by the power of the lock opening, and raised behind the ship when it cleared each lock.

Then even before France fell, due to Fascist sympathies in South America and after 1940 when the French South American possessions (Guyana) came under Vichy control, the program of emergency "closure" which had been designed by the late 1930s to replace the old pre-1920s system was instigated, starting at Gatun Lake. It was called SIP 7 (special improvement project-7). These were emergency closure doors which could be raised in seconds using electric-hydraulic pumps, or in minutes using hand levers on the same hydraulic pumps if the local power plants were knocked out.

For other defenses of the Canal, see:

http://www.army.mil/cmh-pg/books/wwii/Guard-US/ch12.htm

from that is this next:

"During the 1930's, events and technological developments began to challenge the old axioms on which the defense of the Canal had been based. A crippling attack aimed at the locks and dams, and delivered either by an act of sabotage or by naval bombardment, had always been considered the only real danger to be guarded against. The possibility of hostile forces establishing a beachhead and moving overland to the Canal was not entirely discounted, but the absence of suitable landing places on the Atlantic side and the thick jungle of the Pacific lowlands were counted on to discourage any attack of this sort. The Army had disposed its defenses accordingly. Each terminus of the Canal was heavily protected by a concentration of seacoast armament that at one time was regarded as the most powerful and effective of any in the world.

"At the beginning of 1939 the bulk of the garrison defending the Canal was divided between two separate sectors that were about as far apart organizationally as they were geographically. The Pacific Sector had a slight preponderance of force. Assigned to it were the 4th Coast Artillery Regiment, the 33d Infantry, and a battalion of the 2d Field Artillery. At the opposite end of the Canal, in the Atlantic Sector, were the 1st Coast Artillery Regiment and the 14th Infantry. Antiaircraft units made up part of both coast artillery regiments. In addition to these troops assigned to the sectors, certain units were directly under the commanding general of the Panama Canal Department. These department troops included air units-the 19th Wing (composite), with about 28 medium bombers, 14 light bombers, 24 pursuit planes, and a few trainers and utility planes-plus a regiment of combat engineers, together with Signal Corps, quartermaster, and ordnance units, and other service and administrative detachments. The total strength of the garrison-sector as well as department troops-came to approximately 13,500 men. To the Army garrison had been given the mission of protecting the Canal against sabotage and of defending it from positions within the Canal Zone. Close-in defense was thus an Army responsibility except for two specific tasks: that of providing an armed guard on vessels passing through the Canal, and that of maintaining a harbor patrol at the entrances to the Canal. Both of these tasks were entrusted to the Navy, along with its primary responsibility for offshore defense.

"Plans for protecting the Canal against sabotage during an international crisis of this sort had been drawn up in Panama and given constant study ever since the spring of 1936. Now, steps to put them into effect were quickly taken. Three basic measures had been provided for: first, the installation and operation of special equipment in the lock chambers, designed to detect underwater mines and bombs and to prevent damage from this cause; second, the restriction of commercial traffic to one side of the dual locks; and third, the inspection of all ships before they entered the Canal and the placing of an armed guard on vessels while in transit through it. Reinforcements had been arriving in Panama in a steady stream. At the end of January 1940 the strength of the garrison stood not quite at 19,500 men; by the end of April it had risen to approximately 21,100. This build up continued so that when the Japanese attack on Hawaii came, there were nearly 58,000 troops on guard in the Canal Zone, and the Republic of Panama.

The "locks" and "canal" systems themselves were designed to function without electric power except small local generators for the switch boards (1900s), and only by water pressure. The electric "donkey/mule" engines were incorporated much later, replacing real animals and very small generating plants. The loss of a power plant would only slow down, not stop the canal. It was powered by gravity and water pressure, not electricity exactly.

Without the small local electric plants, the system would and could still function all the time even if slightly slower. They might be more vulnerable now to "electric" destruction of the input, but since all the locks were developed to work with simple gravity flow of water, and mechanical motion of the lock gates themselves, I don't see how it would be a major problem in the forties.

But all of that is of no import, General Marshall and Secretary Stimson decided to restrict Canal traffic for an indefinite period; "for the purpose of effecting repairs." In late 1940. What this amounted to was an exclusion of Japanese shipping through the canal; all other vessels were permitted to pass through after close inspection and the placing of American personal onboard. So, as early as July 1941 all ships were being boarded and inspected before they were "escorted" through the canal, and no Japanese ships were allowed to transit the canal. When they were re-routed the Japanese Embassy protested they received a very noncommittal reply from Acting Secretary of State Welles, who had been informed by the War Department of its intentions and who was in complete accord with them.

Unknown to the Japanese the Panama Canal was far from "unprotected" nor was it an easy target, and until long after WW2 the Panamanians were very pro-American. It was the USA after-all who had "aided" their independence from Columbia, and stabilized their economy with the Panama Canal construction project.

When the Japanese hit Pearl, the Central and South American nations rounded up their own Japanese "citizens" and sent them to America for internment where they remained until the war was over. No local spies, no Japanese allowed through the canal, and little input to alert the IJN that the Canal was "waiting" for just such an attack. Not to take anything away from an ambitious if somewhat eccentric plan.

 

Perhaps if Japan could buy licenses for some Wallis skip bombs and modify some Kawanishi H8K flying boats they might overcome the defences ... What, we're not talking about the Twilight Zone? Sorry, my mistake! :lol:

 

Are you inferring something?

 

At Sea.

Two submarines hulls were welded together with a waterproof compartment on deck for three disassembled torpedo bombers.

Hanger deck is a watertight compartment.
Each plane to be assembled on deck.

Two I-400s tied up to tender.

Three I-400s tied up to tender.

Coming home

I-400 Class of Japanese Submarine Aircraft Carriers

 

All this infrastructure to send at most nine light bombers each carrying 800kg tops against a heavily defended target? Doesn't sound too serious to me. We have already discussed the merits of this in the past here:

http://www.ww2f.com/what-if/12112-if-japan-destroyed-panama-cannal.html

If I may quote the redoubtable T.A.Gardner:

 

Doesn't seem to be the best buy for your buck is it?

 

If you sank a ship in the canal it would shut down operations for awhile and slow down supply lines. It would also divert men and weapons away from the front to the canal zone for more defence.

Not a war winning item but it would get the allies attention.

 

But then you would have to wait patiently until two (the locks are double, side by side!) ships were in the best location for that, and then you would have to employ means certain of sinking them. Easy with a gaggle of light bombers? Maybe in the Twilight Zone :lol:

8.99679,-79.59182 - Google Maps

As for defences in the canal zone,

in http://www.globalsecurity.org/military/facility/panama-canal-defense.htm

http://www.ibiblio.org/hyperwar/USA/USA-WH-Guard/USA-WH-Guard-16.html

http://www.babelgum.com/109831/panama-canal-defences-reinforced.htm

 

Surcouf, her 8 inch gun turret in evidence​

This huge submarine carried twin 8 inch guns in a single turret, quite a formidible armament for a submarine, and in a hangar aft of her conning tower was an observation aircraft, a Marcel Berson-411, capable of a speed of 100 knots with a range of 400 kilometres. A cargo of torpedoes, 14 by 500mm, and another 8 by 400mm added to her fighting abilities. A 16 foot motor boat was also on board.

Ahoy - Mac's Web Log - French Submarine Surcouf, the World's largest Submarine before WW2. Her mysterious disappearance in February of 1942.​

 

Not privy on this topic, maybe another member might be, wikipedia for all it's worth claims it was lost off of Bermuda...until someone can prove different, I'll buy this conclusion..it also states it fired on an American destroyer...US Naval records should have a report of this especially since it claims to have killed a naval personal...

Surcouf (N N 3) - Wikipedia, the free encyclopedia

 

You must have missed this,

http://www.ww2f.com/atlantic-naval-conflict/13965-surcouf-what-really-happened.html