U.s. evacuates before pearl Harbor

Not going to happen, pearl Harbor was the main Pacific naval base of the United States.

Mean Japan can sink the American fleet in their decisive battle in the open, which would result in ships sunk who could not be recovered unlike when the sunk in shallow water at Pearl Harbor where many where raised and re-commissioned back into service.

We often hear of wargames of this scenario, and the US Fleet suffers badly being at sea where sunk ships are not recoverable.    But wargames don't occur without combat; how much time does the Japanese Strike Force, or Recon planes have to conduct a search around Hawaii?  If the US Fleet has left Pearl Harbor, how exactly will the Japanese planes find them?   

I think this one largely depends on when the harbor is emptied, and the direction the US Fleet takes.   If the harbor is evacuated by 1:00 am local time, and the fleet takes a course Southwest at 12 or  15 knots (IIRC, at the time it was thought the Japanese would approach from the Southwest), the Fleet would be 84 or 105 miles away.    At 5,000 feet altitude, the horizon is just over 82 miles; the US Fleet will be out of sight of the Japanese planes at that altitude.  (I'm not sure what altitude the Japanese flew to Pearl Harbor, it might have been lower. )

If the fleet is detected, how will the Japanese fare against a fully closed ship, with all AA batteries manned and ready for attack and able to maneuver?   And the other side of the wargames with the fleet 'at sea'; how do the Japanese avoid the historic over-concentration that saw West Virginia hit with seven (maybe 9) torpedoes and Oklahoma hit with five?   I would also note the Standards had a reputation for being very maneuverable battleships.  I think the Japanese will not do as well as historic, but will suffer more aircraft losses to AA fire.

Also, the raid was not just against the ships.    The airfields around Pearl Harbor were targeted as well as Kaneohe NAS on the Eastern coast of Oahu.  Would the Japanese split the strike force, the torpedo and level bombers searching for the ships while the dive bombers and fighters go after the airfields?  And they would only be splitting when they find the harbor and airfields empty.   The aircraft from those airfields would be airborne, and the 36 PBYs from Kaneohe would be out searching for the Japanese.   When the Japanese strike force arrives over the island, they're going to get a very harsh reception.   And the Japanese can't afford heavy losses in planes and pilots.    If they suffer numerous losses, future operations will be in jeopardy, including deploying to Wake Island, the Netherlands East Indies, the Indian Ocean raid and Coral Sea.

Pennsylvania has her screws removed, so she, Cassin and Downs in drydock, as well as Shaw in the floating drydock are likely not going anywhere.   If the rest of the harbor is empty, those ships left behind will likely bear the brunt of the attack, including Utah and the ex-armored cruiser Baltimore.  

My thoughts,

Did the Japanse have people on the island who could communicate back to Tokyo that the US Pacific Fleet was no longer in Pearl Harbor.



 

Takeo Yoshikawa was the Japanese spy in Hawaii.   He was watching the fleet from Pearl City and Aiea Heights on the December 6th.    But if the fleet leaves in the early morning hours of the 7th, how will he know?

He did send a coded message to Tokyo on the 6th, but if he was up at dawn and saw the fleet gone, could work get to the carrier in time?   IIRC, the strikes would already be launching.    In addition, were the Japanese carriers listening for his reports or would they have to be turned around by command in Tokyo?

Regards,

Do they?   Their main task was to cripple the US Fleet.   Damaging the military facilities helped that to happen, but what would they really do against the docks and oil tanks?    And the oil tank farms were very hard to hurt.    It won't be like the movies where entire fields will be set ablaze.   Each tank was surrounded by an earthen berm to keep any oil leek contained.    Also, the bunker oil would be very hard to set alight by strafing.    In addition, the level bomber Kates are carrying converted 14in battleship shells for use against Battleship Row.   They'll be next to useless against the facilities and tank farms.   Historically, their main success was Arizona; they might make a run on Pennsylvania in drydock, but after her they have no real targets.  

A map showing the location of the oil tanks near Pearl Harbor



Regards,

I don't know if they panic, but they definitely fail to cripple the US Fleet.  

But I think you have the start of a great scenario there.   What if a US submarine sights the Japanese turning south?    

In the predawn darkness of the 7th, the deck crews are warming up the strike's engines on deck.  As the first light flickers over the horizon, the US battleline is sighted ahead of Nagumo's force, with New Orleans and San Francisco sighted off to port.   What does Nagumo do?   What do Kimmel and Pye do?

Regards,