KB Fuel Level Too High - Discuss

[jmscho]

What do players think about the initial fuel levels of the KB in the historic start scenarios of WitP and/or WitP AE?

Should it be possible for the KB to stay in the PH area delivering strikes for several days or stay a bit further away in the hope of catching returning US CVs.

Are such activities considered gamey?

[aprezto]

I'd say No to both. I might think that the tankers would be low on fuel, but I am pretty sure they topped the carriers up before the strikes.
 
And no again for staying around. It is Ahistorical is all, if the Jap commander wants to keep using his torpedos up against Pearl he is likely to get a very nasty surprise from the allied carriers.

[Brady]

I posted this recently in regards to a similar inquery:

From J-Aircraft:

IMO, there is no truth to the suggestion that the TF lacked fuel resources for an extended stay at Hawaii. Combined Fleet had provided 80,000 tons of additional fuel oil, plus about 4,000t more on 2nd CAR DIV, Akagi and 8th CRUDIV. One of these tankers might have broken down, making it around 70,000 tons. 5TH CARDIV (about 11,000 tons internal capacity) returned to Japan with 1,700 tons of oil still aboard, but had only received 700 tons resupply during the entire operation. DD Akigumo burned 1,100 tons during the mission (her internal capacity was about 500 tons), meaning the entire DD force should not have taken on much more than 6,000-8,000 tons from the tankers during the raid. Kaga and the two battlecruisers had the range to perform the mission without refueling, so for these units and Akagi, refueling was also probably minimal.

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.


5th Carrier used about 10,000 tons between Shokaku and Zuikaku for the entire mission. Figure Akagi and Kaga and the two BC’s to be heavier consumers and 2nd Car Div and the heavy cruisers to be lighter consumers than that. Each destroyer burned less than 1,200 tons and the light cruiser – call it 2,000 just to be on the high side. That’s 10 heavy units @ 50,000 + about 10 destroyers @ 22,000 + 1 light cruiser @ 2,000 = <74,000 tons. The attack unit could carry about 45,000 tons of fuel. Plus another 4,000 tons overloaded, plus 80,000 on tankers = 129,000 tons. The surplus is 59,000 tons, or 49,000 if one broke down. Nagumo could expend most of his ammunition and avgas in 3 days of intensive ops, so he had the fuel

Prety much the only time KB hangs around Pearl is when you do a Non-Historic start.

[Mike Scholl]

ORIGINAL: jmscho

What do players think about the initial fuel levels of the KB in the historic start scenarios of WitP and/or WitP AE?

The programming doesn't seem to permit "partial fuel" at the start of a scenario. But the "support Tankers" TF ought to start "empty". That still leavees KB with ample fuel to hang around a couple days and sail all the way back to Japan (In fact, the AI won't even attempt to refuel on the return voyage). Fuel in the tankers just makes "gamey" efforts possible by players...

[Dili]

The programming doesn't seem to permit "partial fuel" at the start of a scenario.

Is this confirmed?

[Nikademus]

yes it does.


Guad scenario has carrier TF's starting at 50% capacity

[herwin]

ORIGINAL: jmscho

What do players think about the initial fuel levels of the KB in the historic start scenarios of WitP and/or WitP AE?

Should it be possible for the KB to stay in the PH area delivering strikes for several days or stay a bit further away in the hope of catching returning US CVs.

Are such activities considered gamey?

The KB had just enough fuel to go to Pearl, launch two deckload strikes per carrier, and make it back to Kure. If the US Fleet had been at Lahaina Roads (as it should have been given that Short and Kimmel had been warned several times about the Japanese propensity for surprise attacks), the KB lacked the additional fuel needed to find it, and would have trashed the Pearl Harbour base facilities instead. The Japanese were upset about not catching the carriers in port in any case.

[herwin]

ORIGINAL: Brady

I posted this recently in regards to a similar inquery:

From J-Aircraft:

IMO, there is no truth to the suggestion that the TF lacked fuel resources for an extended stay at Hawaii. Combined Fleet had provided 80,000 tons of additional fuel oil, plus about 4,000t more on 2nd CAR DIV, Akagi and 8th CRUDIV. One of these tankers might have broken down, making it around 70,000 tons. 5TH CARDIV (about 11,000 tons internal capacity) returned to Japan with 1,700 tons of oil still aboard, but had only received 700 tons resupply during the entire operation. DD Akigumo burned 1,100 tons during the mission (her internal capacity was about 500 tons), meaning the entire DD force should not have taken on much more than 6,000-8,000 tons from the tankers during the raid. Kaga and the two battlecruisers had the range to perform the mission without refueling, so for these units and Akagi, refueling was also probably minimal.

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.


5th Carrier used about 10,000 tons between Shokaku and Zuikaku for the entire mission. Figure Akagi and Kaga and the two BC’s to be heavier consumers and 2nd Car Div and the heavy cruisers to be lighter consumers than that. Each destroyer burned less than 1,200 tons and the light cruiser – call it 2,000 just to be on the high side. That’s 10 heavy units @ 50,000 + about 10 destroyers @ 22,000 + 1 light cruiser @ 2,000 = <74,000 tons. The attack unit could carry about 45,000 tons of fuel. Plus another 4,000 tons overloaded, plus 80,000 on tankers = 129,000 tons. The surplus is 59,000 tons, or 49,000 if one broke down. Nagumo could expend most of his ammunition and avgas in 3 days of intensive ops, so he had the fuel

Prety much the only time KB hangs around Pearl is when you do a Non-Historic start.

I beg to differ. I did the logistics analysis about 30 years ago, and the fuel was very marginal when you take into account the costs of flight operations and the high speed runs.

[Mynok]

Well just show us how that force used 129,000 tons of fuel up then. [8|]

[Brady]

glenn239 @ J-Aircraft is the source for the Above passage, and he offerd this up as well concerning the Tankers:

Tankers-

Empty getting to Hawaii? Not a chance. The average pumping rate might have been about 70 tons per hour. At that pace, to empty a 10,000 ton load would require 6 entire days of the journey. But refueling what, exactly? The records for 5th Car Div and the Bat Sqd (4 of the 8 heavy units) indicate that these units took on maybe 3,000 tons for the whole mission. The destroyers may have accounted for about 12,000 tons, but they started with about 5,000. So that's 4 heavy and about 10 light units accounting for around 10,000 tons of the tanker's 80,000 ton capacity.

Nagumo's main consideration with fuel was running the destroyers low during extended operations near Hawaii. His order to the unit before the attack indicates he planned to use the heavy units to refuel the destroyers, if this became necessary.

[Mike Scholl]

ORIGINAL: Nikademus

yes it does.
Guad scenario has carrier TF's starting at 50% capacity

Is this after a "magic move" Nik?

[Mistmatz]

ORIGINAL: Mike Scholl

ORIGINAL: Nikademus

yes it does.
Guad scenario has carrier TF's starting at 50% capacity

Is this after a "magic move" Nik?

Scenario 001 has many vessels disbanded in port with less than 100% endurance, therefore I believe this is a simple field in the scenario files.

[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.

[herwin]

ORIGINAL: Mynok


Well just show us how that force used 129,000 tons of fuel up then. [8|]

I'll post this in two stages.

OK, there are a number of issues you have to take into account:

1. Some of the IJN warships were lightly built and top-heavy, and had to retain some fuel for ballast.
2. Air operations took place at 24-26 knots and required extra fuel (about 3-4x as much as for cruise speeds).
3. The final approach to Hawaii was a long high-speed run at 20-26 knots, using 2-4 times as much fuel as cruise speeds. This was a key planning constraint. If the destroyers could not be refueled completely, they would have been left with the tankers. While in the vicinity of Hawaii, the KB operated at about 25 knots.
4. The quoted data were for ships in clean and new condition.
5. Refueling operations were vulnerable and slow (9-12 knots) and could not be performed safely if there was danger of air or surface attack. In the north Pacific most winters, no more than 1 day in 10 was suitable for refueling operations due to weather, although the KB was favoured by good weather.
6. CVTFs needed to be out of range (about 200 nm) of enemy SAGs at night and when air operations were shut down.

Data:

These give nominal bunkerage and range. The distance travelled by the DD Akigumo from beginning to end was 8593 nm. This included about 1000 nm at 24 knots and 7600 nm at 14 knots. Akigumo was refueled 12 times during the trip, for a total of about 512 tons, burning 1079 tons in total. The refueling after the attack on Pearl Harbour was 250 tons, about 8 times normal daily usage. The Pearl Harbour run cost the destroyer 0.25 tons per NM, while the remainder of the voyage cost about 0.1 tons per NM.

Kongo class: 6330 tons of fuel, 10000 nm@14 knots (required refueling, Hiei at least 354 tons, Kirishima at least 469 tons)
Akagi: 5775 tons of fuel plus 1450 tons supplemental, 8200 nm@16 knots (also required refueling since she could only cruise 60% of the distance)
Kaga: 8208 tons, 10000 nm@16 knots
Soryu:3670 tons plus 350 tons supplemental, 7750 nm@18 knots (also required refueling since she could only cruise 60% of the distance)
Hiryu: about 4400 tons plus 350 tons supplemental, 7670 nm@18 knots (another source 10330 nm@18 knots!) (required refueling since she could only cruise 60% of the distance)
Shokaku class: 4100 tons (another source 3500 tons, war diary indicates about 5500 tons, which I trust), 9700 nm@18 knots (Z refueled once for 350 tons, had 1700 tons of fuel left upon return, so she used about 4000 tons)
Tone/Chikuma: about 2000 tons plus 290 tons each supplemental, 8000nm@18 knots (refueled)
Abukuma: unknown bunkerage, 9000nm@10 knots (refueled)
11 Destroyers: 500-600 tons, 5000-5700nm@14 knots, about 1000nm@34 knots (required 30 tons/day during cruise and refueled often)
The seven fastest tankers available.

Total usage was about 60-70,000 tons. About 75% was spent on the voyage and 25% on the attack. An additional day at Pearl would have had the destroyers and some of the carriers running on fumes at the end of the attack. Given the North Pacific weather, it might have been a few days until they could refuel.

Only the Kaga and Shokakus could reach Hawaii and return without refueling. The track was Hitokappu Bay to 42N 165W at 14 knots, then to 32N, 157W (700 NM due north of Pearl Harbour), then south to a point about 230 NM north of Pearl Harbour at 24-26 knots, and finally return. The DD screen was to return to Hitokappu Bay if it couldn't be refueled during the first leg due to bad weather.

Lahaina anchorage was reconnoitered. Consideration was given to returning via the west side of Oahu. If the US Fleet was at Lahaina, the attack was to be just with torpedoes.

[Andrew Brown]

ORIGINAL: Nikademus

yes it does.


Guad scenario has carrier TF's starting at 50% capacity

A good idea.

To provide more accuracy for any scenario, reduced fuel levels could be applied to all ships that start in TFs, including the KB. At present they do have more fuel available than they did in Real Life.

Andrew

[Scott_USN]

ORIGINAL: jmscho

What do players think about the initial fuel levels of the KB in the historic start scenarios of WitP and/or WitP AE?

Should it be possible for the KB to stay in the PH area delivering strikes for several days or stay a bit further away in the hope of catching returning US CVs.

Are such activities considered gamey?

The KB in my game didn't wait around it whacked everything on its way out on the second day it was still killing stuff which is practical given that the CAG was at speed heading back so air ops are easy enough when you are running away.

If it hangs around for more than 2 days in place than well it may be a bug but in my 7 game starts it always left the second days killing things on the way out and hitting wake on its way past but not staying there. Maybe Ahistorical start is different I don't know.

[spence]

Admiral Yamaguchi was and early avid adherent to Yamamoto's Pearl Harbor plan. He seriously proposed that Hiryu and Soryu make the strike and then be scuttled when they ran out of fuel. It doesn't sound like the fuel situation was in the least inconsequential as apparently asserted, with many unsubstantiated figures, by the author of the article on the j-aircraft forum. The evidence from numerous sources suggests that fuel constraints dictated much of what occurred. A second strike on the afternoon of December 7th or on Dec 8th might just have been possible and Nagumo may be rightly criticized for pulling back. Several days/a week of pounding the American base(s) in the fashion of the 1945 TF38/58 was beyond KB's abilities.

[herwin]

BTW, one implication is that carrier airstrikes should be expensive in CVTF endurance. Assume a CVTF has a cruise speed of 15 knots, costing 180 endurance per resolution phase (12 hours). An AM or PM offensive air operations phase (6 hours) should cost 375 endurance or about twice as much.

[bklooste]

Ok Some comments to stay at Pearl a week would not add any fuel only if they were moving around Pearl. Avgas is a different matter and is not fuel nor does it come from the ships fuel tanks. It is worth noting the original plan was to suicide some carriers so if some carriers ran out of fuel on the way back to japan it is no big deal and some oilers would be sent anyway if the commander decided to extend the trip ; Hence it would have no game impact.

Do a lot of players till return via Truck ?

Rest in line.

I'll post this in two stages.

1. Some of the IJN warships were lightly built and top-heavy, and had to retain some fuel for ballast.

> Dont think any of these were top heavy Anyway they can pump sea water for ballast.

2. Air operations took place at 24-26 knots and required extra fuel (about 3-4x as much as for cruise speeds).

>Only for the hour of launch and not at all if there was a good wind. Anyway this time is very minor compared to the total.

3. The final approach to Hawaii was a long high-speed run at 20-26 knots, using 2-4 times as much fuel as cruise speeds. This was a key planning constraint. If the destroyers could not be refueled completely, they would have been left with the tankers. While in the vicinity of Hawaii, the KB operated at about 25 knots.

>This is at the players discretion after the initial strike. They could just operate at 12 knots and accelerate when needed they had plenty of spotting so would have plenty of warning. After the first strike results i dont think there was much need for fast steaming.

4. The quoted data were for ships in clean and new condition.

> The big problems were the 2 new carriers which were new...Anyway the ships were well serviced before the strike so should be at peak capability.

5. Refueling operations were vulnerable and slow (9-12 knots) and could not be performed safely if there was danger of air or surface attack. In the north Pacific most winters, no more than 1 day in 10 was suitable for refueling operations due to weather, although the KB was favoured by good weather.

>This was already completed where needed.

6. CVTFs needed to be out of range (about 200 nm) of enemy SAGs at night and when air operations were shut down.

Data:

These give nominal bunkerage and range. The distance travelled by the DD Akigumo from beginning to end was 8593 nm. This included about 1000 nm at 24 knots and 7600 nm at 14 knots. Akigumo was refueled 12 times during the trip, for a total of about 512 tons, burning 1079 tons in total. The refueling after the attack on Pearl Harbour was 250 tons, about 8 times normal daily usage. The Pearl Harbour run cost the destroyer 0.25 tons per NM, while the remainder of the voyage cost about 0.1 tons per NM.

Kongo class: 6330 tons of fuel, 10000 nm@14 knots (required refueling, Hiei at least 354 tons, Kirishima at least 469 tons)
Akagi: 5775 tons of fuel plus 1450 tons supplemental, 8200 nm@16 knots (also required refueling since she could only cruise 60% of the distance)
Kaga: 8208 tons, 10000 nm@16 knots
Soryu:3670 tons plus 350 tons supplemental, 7750 nm@18 knots (also required refueling since she could only cruise 60% of the distance)
Hiryu: about 4400 tons plus 350 tons supplemental, 7670 nm@18 knots (another source 10330 nm@18 knots!) (required refueling since she could only cruise 60% of the distance)
Shokaku class: 4100 tons (another source 3500 tons, war diary indicates about 5500 tons, which I trust), 9700 nm@18 knots (Z refueled once for 350 tons, had 1700 tons of fuel left upon return, so she used about 4000 tons)
Tone/Chikuma: about 2000 tons plus 290 tons each supplemental, 8000nm@18 knots (refueled)
Abukuma: unknown bunkerage, 9000nm@10 knots (refueled)
11 Destroyers: 500-600 tons, 5000-5700nm@14 knots, about 1000nm@34 knots (required 30 tons/day during cruise and refueled often)
The seven fastest tankers available.

Total usage was about 60-70,000 tons. About 75% was spent on the voyage and 25% on the attack. An additional day at Pearl would have had the destroyers and some of the carriers running on fumes at the end of the attack. Given the North Pacific weather, it might have been a few days until they could refuel.

> 60-70K is a long way from 130K capacity . So you are just talking about tanker refuel time. Most of this can be done near the Bonin islands on the way back.
> Also it is quite viable to launch an attack and loiter at 12 knots ( if the player excepts the risk) or even run out of fuel on the way back and meet some AOs sent from Hiroshima around the Bonin islands. ie reducing the fuel will have no impact on multi day strikes.

[herwin]

ORIGINAL: bklooste


Ok Some comments to stay at Pearl a week would not add any fuel only if they were moving around Pearl. Avgas is a different matter and is not fuel nor does it come from the ships fuel tanks. It is worth noting the original plan was to suicide some carriers so if some carriers ran out of fuel on the way back to japan it is no big deal and some oilers would be sent anyway if the commander decided to extend the trip ; Hence it would have no game impact.

My point is that the logistical details matter in naval planning. For the Pearl Harbour attack they centred on the fuel costs. If there had been a gas station at 32N 157W, the same planning factors would have controlled the feasibility of the operation, except that Short and Kimmel would not have been quite so fat, dumb, and happy.