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Brady -> RE: KB Fuel Level Too High - Discuss (8/14/2009 8:48:44 PM)
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More from Glen, refering to Herwins:
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.
I’ve never seen a reference giving refueling information for 1st or 2nd Car Div. Have him provide it. His claim that 5th Carrier made the trip “without refueling” is wrong; the log of the 5th CAR DIV shows that at least Zuikaku was refueled once. 3 BAT DIV’s log shows only one refueling, for a total of 823 tons (at about 60 tons/hour). Zuikaku took on 350 tons from a tanker, giving a total usage for this carrier of 4,150 tons during the whole mission.
Re - Akagi using, “35%” of its fuel bunkerage, “for the attack run”.
Fuel burn rates differ from ship to ship, but roughly the function is that for every ton burned at 12kt, 1.25 tons are burned at 16kt, 2 tons are burned at 18kt, 4 tons at 24kt, 5 tons at 26kt, 9 tons at 30kt and 14 tons at 36kt. So, when 2nd CAR DIV and 8th CRU DIV made their 24 hour 30kt run to Wake (which your poster appears to have included in his mission figures), they consumed about 9 times the fuel in comparison to normal cruising speed.
Bunkerage was about 6,000 tons for Akagi and the attack run was 24hrs in duration. For Akagi to burn 2,000 tons in 24 hours would require a burn rate of 83 tons per hour. In the US fleet, an equivelent ship to Akagi was roughly the Saratoga. USN records indicate that this was the worst fuel pig in the entire US Navy, and burned 1435 tons per day at 26kt.
For Hiryu, the USS Ranger would be in the ball park, and Ranger burned 435 tons/day at 26kt (which would be about 12% of Hiryu’s bunkerage). In both cases, the poster is including the 24 hour run away from Hawaii in the “attack run” total, and Hiryu’s figure will still be exaggerated even with this addition.
Akagi had aboard 1,450 tons extra oil. Soryu and Hiryu 700 tons each. They should have re-supplied daily on the way over, to keep their tanks topped up. 2nd Car Div timed it so that it would finish off its surplus (barreled) fuel during the night of the approach to Hawaii. Akagi will have done the same thing, meaning that all three ships should have been near to full capacity on the morning of the attack, because in each ship the stored extra was greater than the requirement for the run in.
For further comparison, Essex burned 17 tons per hour at 24kt and Yamato burned around 45-50 tons. Yamato’s displacement was about 65,000 tons, Akagi’s was 41,000 and Hiryu’s about 19,000.
How dificult was it for the DD's to refuel from the Captail Ships?
Not any more difficult than from a tanker. Nagumo’s order reads,
From CO of Task Force, 5 Dec, to Task Force, recieved 0815 5 Dec (signal). Task Force Signal Order No. 19 Paragraph 3: In case the rendezvous with the 1st Supply Group could not be made, it is planned that destroyers in guard missions be refueled from carriers and Abikuma and Tanikaze from the Third Battleship Division.
Nagumo knew his business – he’d not have given this instruction if he thought the task was too difficult to perform. I'd simply tune out anyone saying that the Japanese "couldn't" do that.
How Many days worth of fuel did the DD's have on hand after their dash in?
A DD would burn about 120 tons per 24hr at 24kt. I think capacity was about 550 tons. The final refueling was just before the dash to the launch point.
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