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ORIGINAL: herwin



About 13000+ tons of fuel transferred prior to the attack run, 13500 afterwards, refueling during and after the return trip was about 34000 tons, total fuel used was about 64000 tons. Kaga, Zuikaku, and Shokaku made the trip without refuelling; the rest refuelled on a regular basis. Fleet bunkerage capacity was 56000+ tons, with another 3000 tons of fuel in drums etc. If Halsey had caught the replen TF on the 7th, there was enough fuel left to make Truk if the destroyers were refuelled from the heavy ships (an ad-hoc manoeuvre in the IJN). The destroyers used 56% of their fuel bunkerage and the cruisers, Akagi, Soryu, and Hiryu used about 35% of their fuel bunkerage for the attack run.

What glen offered up in our dischion of this subject:

So to distill it down, to the simplest of terms, when KB and their atendent tankers returned home they had used slightly less than half the fuel they had started with.(me)

That is my guess, yes – about 60,000 tons remaining of about 125,000. That does not include the Wake Island diversion, but assumes all units return to Japan. Kido Butai’s logistic leash was its bombs and avgas, not fuel. (glenn)

Which means the Tankers at Games start would still be prety much full. And their would be plenty of fuel again for a few days at Pearl.

ORIGINAL: Brady


What glen offered up in our dischion of this subject:

So to distill it down, to the simplest of terms, when KB and their atendent tankers returned home they had used slightly less than half the fuel they had started with.(me)

That is my guess, yes – about 60,000 tons remaining of about 125,000. That does not include the Wake Island diversion, but assumes all units return to Japan. Note that Yamamoto had more tankers with the Main Body, and I think the Midway attack unit had one too. Kido Butai’s logistic leash was its bombs and avgas, not fuel. (glenn)

Which means the Tankers at Games start would still be prety much full. And their would be plenty of fuel again for a few days at Pearl.

Sorry Brady, but Glen was thinking about MI, not PH, when he wrote about Yamamoto and the Main Body. For PH, no tankers remained with Kido Butai for the last leg of the operation conducted at a battle speed of 24 knts which did not allow them to keep up with KB. in that stage they remained behind screened by two DDs.

Cheers

Gilbert

ORIGINAL: Brady

ORIGINAL: herwin



About 13000+ tons of fuel transferred prior to the attack run, 13500 afterwards, refueling during and after the return trip was about 34000 tons, total fuel used was about 64000 tons. Kaga, Zuikaku, and Shokaku made the trip without refuelling; the rest refuelled on a regular basis. Fleet bunkerage capacity was 56000+ tons, with another 3000 tons of fuel in drums etc. If Halsey had caught the replen TF on the 7th, there was enough fuel left to make Truk if the destroyers were refuelled from the heavy ships (an ad-hoc manoeuvre in the IJN). The destroyers used 56% of their fuel bunkerage and the cruisers, Akagi, Soryu, and Hiryu used about 35% of their fuel bunkerage for the attack run.

What glen offered up in our dischion of this subject:

So to distill it down, to the simplest of terms, when KB and their atendent tankers returned home they had used slightly less than half the fuel they had started with.(me)

That is my guess, yes – about 60,000 tons remaining of about 125,000. That does not include the Wake Island diversion, but assumes all units return to Japan. Kido Butai’s logistic leash was its bombs and avgas, not fuel. (glenn)

Which means the Tankers at Games start would still be prety much full. And their would be plenty of fuel again for a few days at Pearl.

The leash was how far it could sail at 24 knots without refuelling.

ORIGINAL: herwin



The leash was how far it could sail at 24 knots without refuelling.

Your refering to (?) :

The destroyers also needed to make a 48hr run at 24-28kt to enter and clear the battle zone, but Nagumo was capable of resupplying these from his battleships and carriers.

ORIGINAL: Brady

ORIGINAL: herwin



The leash was how far it could sail at 24 knots without refuelling.

Your refering to (?) :

The destroyers also needed to make a 48hr run at 24-28kt to enter and clear the battle zone, but Nagumo was capable of resupplying these from his battleships and carriers.

Under air, naval, and submarine attack?

ORIGINAL: herwin

ORIGINAL: Brady


[Aparently only about 10,000 tons of the Tankers 80,000 ton capacity had be taken from them.

About 13000+ tons of fuel transferred prior to the attack run, 13500 afterwards, refueling during and after the return trip was about 34000 tons, total fuel used was about 64000 tons. Kaga, Zuikaku, and Shokaku made the trip without refuelling; the rest refuelled on a regular basis. Fleet bunkerage capacity was 56000+ tons, with another 3000 tons of fuel in drums etc. If Halsey had caught the replen TF on the 7th, there was enough fuel left to make Truk if the destroyers were refuelled from the heavy ships (an ad-hoc manoeuvre in the IJN). The destroyers used 56% of their fuel bunkerage and the cruisers, Akagi, Soryu, and Hiryu used about 35% of their fuel bunkerage for the attack run.

Given 3 CVs did not refuel at all, I'd be interested to know how many times did the shortest-legged CV Soryu, replinished 100% of her total bunkerage? Or indeed how refuelling broke down per ship. 64000 tons drawn from the tankers (if I'm reading that right) seems quite a lot.

The problem is strong anectdotal evidence from Japanese sources would suggest that quantity of fuel carried was not a big problem for staying a few days longer.

Yamaguchi, Fuchida and Genda all wanted and recommended further strikes or a hunt for the US carriers - I'd love to know what they were all thinking of if the fuel margin precluded it. Prange relates the Combined Fleet staff urged further action also, and Ugaki recorded his opinion as being "Had I been the C-in-C of the task force...I would have firmly resolved to continue the attack strongly...until Pearl Harbour was completely destroyed." Some Japanese pilots apparantly were dismayed no further strikes would be launched - but Nagumo's own reasons for withdrawing (as relayed to his own fliers by Genda) did not mention fuel as a factor at all. Which seems most odd if the margins were that tight.

This is not to downplay the real and serious practical difficulties of underway refuelling in a battle zone, with potentially stormy seas to contend with also. However, in the absence of original Japanese data, I'm inclined to take the options considered at the time, by First Air Fleet and Combined Fleet staff, as viable ones.

ORIGINAL: herwin



Under air, naval, and submarine attack?

As noted above, they were not nescessarly subject to any of these threats, real or preceaved, they also did not have to sail at that spead either the entire time(During the in and out dash phase).

We know That Historicaly that when they got home they had as noted above half (about) the fuel they started with, which leaves a very wide margine on the scean to alow for operations (hypothetical).

........

Game- in the game refuling is alowed when ever a player wants to alow it, just by clicking the button, weather this should be so is a subject for another time I think, but it is and for all sides.

All sides also start with their ships to full as well imo, but if the topic of this debate is weahter or not KB had Historicaly enough fuel on hand to conduct a three day stay at pearl...

I think its prety clear they did.

I think the idea of the Japanese having enough fuel to stick around Pearl for a week is just bogus!

If the Japanese had that much fuel, they could have hit Pearl then gone and hit the aircraft factories around Seattle or the west coast, or going hunting for the US carriers, which they couldn't.

"I think its prety clear they did."

"On hand", is NOT the same as "in the destroyers bunkers, ready to be burned".  Historically, they had enough fuel, in the capital ships, to remain on station.  Historically, the DDs had to be refueled multiple times.

Whether they could have successfully refueled the DDs from the capital ships (a time consuming process under any circumstances) after launching the PH attack is a completely different question.  Then you'd have to determine whether or not their location would have been discovered by the search planes PH sent out.  Whether PH could have launched airstrikes.  Whether any subs could have been vectored to their location.  Whether the USN CVs could have reached an attack point.  Whether the naval units at PH would have sortied and tried to reach the Japanese location.  If any (or all) of these things happened, it would have interrupted the refueling process, quite possibly leaving the DDs without enough fuel to get home or do any combat manuevering.  With the Japanese being caught at low speed, maintaining a steady course, unable to conduct air ops, and with their DDs tethered to their capital ships. 

But, say, 3 or even 4 days pad?

What were the Japanese staff officers talking about if not?

ORIGINAL: pad152

I think the idea of the Japanese having enough fuel to stick around Pearl for a week is just bogus!

If the Japanese had that much fuel, they could have hit Pearl then gone and hit the aircraft factories around Seattle or the west coast, or going hunting for the US carriers, which they couldn't.

That's a pretty classic circular argument you've got there.

Is it because they couldn't, or because they didn't want to risk it?

Why didn't i think of that? [:)] Its not like KB isn't needed elsewhere.

Lets go to San Fran!

The issue is less about the fuel (enough for at least 3 days or so depending on the level of risk taken for refuleing ops and return home), it is about perfect intellegence and hindsight which Nagumo did not have the benefit like WitP AE players.

Japanese players KNOW what is at PH, where the American Carriers are, how effective (or ineffective) the Allies follow on response is, and how devestatingly effective the PH attack was/will be.

The demons that Nagumo saw due to a huge black hole of knowledge on US dispositions and effectiveness, as well as limited experience with CV operational effectiveness as a whole (effective CV ops just really beginning in terms of operations, battle damage, etc..) forced him to protect Japan's CV force a long way from home (that if significantly damaged would have to be scuttled most likely).

Players can hang around and pummell PH without much risk knowing so many things with a level of surety.

ORIGINAL: Nikademus

Why didn't i think of that? [:)] Its not like KB isn't needed elsewhere.

Lets go to San Fran!

Let's!! I hear they've got some D-licious sourdough bread and chocolate....

ORIGINAL: treespider

ORIGINAL: Nikademus

Why didn't i think of that? [:)] Its not like KB isn't needed elsewhere.

Lets go to San Fran!

Let's!! I hear they've got some D-licious sourdough bread and chocolate....

And you must not forget the crabs. King crabs are much sweeter than our Caribean blues. The Japanese should love them. [;)]

JWE knows how to reduce the fuel for the game start. His boat will be at Panama sometime Saturday and he can communicate. So if this is a problem and he agrees he can say what to do and I can execute.

MO

ORIGINAL: JuanG

You can set up partial fuel/endurance values for ships in the editor, yes.

You cannot set up a tanker with a partial fuel load however - which is what would be needed here.

This could be simulated rather easily. (Caveat - In the following analysis I don't have the real figures and am just making up numbers for the purpose of discussion):

Assume the Japanese Replenishment force contained 10 tankers, each carrying 10,000 lbs of fuel for a total of 100,000. If the "real" fuel on hand situation was 50,000 at the start of the 12/7 operation, simply set up the 10 ship TF so it contains 5 empty tankers and 5 full ones. The game effect will mimic RL in that all ten tankers are accounted for, AND the total available fuel is at the historical level.

Edit: Or use a somewhat "gamey" technique. Set the fuel capacity of all 10 tankers to 5000 each, and give them a 12/8/41 "upgrade" which jumps the capacity to 10,000 the next time they are in port. (Of course, this assumes there are upgrades which do nothing other than adjust carrying capacity.)

Reducing the KB "hang-around time" could be done by making adjustments to the ammunition loads - i.e. give the carriers only enough for about 4-5 strikes - if all are used the carriers have zero left in reserve to counter an Allied Carrier intervention. Even the most gung-ho of Nagumo's advisors weren't advocating hanging around Pearl until the 12th, and thus it really shouldn't be possible to do that.

ORIGINAL: Brady

ORIGINAL: herwin



Under air, naval, and submarine attack?

As noted above, they were not nescessarly subject to any of these threats, real or preceaved, they also did not have to sail at that spead either the entire time(During the in and out dash phase).

We know That Historicaly that when they got home they had as noted above half (about) the fuel they started with, which leaves a very wide margine on the scean to alow for operations (hypothetical).

........

Game- in the game refuling is alowed when ever a player wants to alow it, just by clicking the button, weather this should be so is a subject for another time I think, but it is and for all sides.

All sides also start with their ships to full as well imo, but if the topic of this debate is weahter or not KB had Historicaly enough fuel on hand to conduct a three day stay at pearl...

I think its prety clear they did.

This might help. B3300 is the tons burnt during each of the cruises (3300 nm). B2800 is the tons burnt during the operations around Pearl Harbour (1000 NM, but 2800 endurance). Apologies for the misnamed BB and the misspelling of bunkerage. This spreadsheet was not intended for public dissemination.

I agree with denisonh the real story is not that what the AI or PBEM players are doing, its that they are able to do so with the unquestioned knowledge of hindsight. The knowledge of where things are and how heavily or lightly defended a target is. Admirals and Generals are by nature somewhat conservitive. The fate of their nation often rest on the decisions they make. We loose some pixels and bytes. Real Admirals loose ships, men, and blood.

ORIGINAL: ltfightr

I agree with denisonh the real story is not that what the AI or PBEM players are doing, its that they are able to do so with the unquestioned knowledge of hindsight. The knowledge of where things are and how heavily or lightly defended a target is. Admirals and Generals are by nature somewhat conservitive. The fate of their nation often rest on the decisions they make. We loose some pixels and bytes. Real Admirals loose ships, men, and blood.

Sorry about being grumbly. I try to ride my bicycle to work, but on Wednesday I had a head-on collision with a car that was being driven by a kid on the wrong side of the road. The bike is in the shop, and I'm aching.

The bike is in the shop, and I'm aching.

Better than the other way round!