Cover up synopsis

Discussions about the history of the ship, technical details, etc.
Byron Angel
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Re: Cover up synopsis

Postby Byron Angel » Thu Dec 15, 2016 7:26 pm

Is there any indication as to when Leach became concerned about fuel state?
Even the difference of a few knots can make a large difference in fuel consumption when operating at high speed.

B

alecsandros
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Re: Cover up synopsis

Postby alecsandros » Thu Dec 15, 2016 8:58 pm

@Cag
We must remember also that Prince of Wales was shadowing Bismarck, and lacking further concrete orders, she would not attempt to engage from a very unfavorable angle of approach. Thus when Bismarck reduced speed to 22, later 16kts, it makes sense Prince of WAles also reduced speed, or adopted a different course, as to not reduce distance to the enemy by to much. This may help explain the speed drops and ups from over the day. (remember at 18:00hours, the second battleship duel took place from 27km...)

However, Leach's messages to the Admiralty had a different weight and importance, as based on those messages the Admiralty could adopt various decisions. So it was critical to inform them in a very accurate way. What "accurate" could mean in that context is difficult to know. Could be long-term sustainable speed, and it could be exactly what he said - "maximum speed"...

@Byron
Leach transmitted he had 1600tons of fuel available at 12:53 (IIRC), so roughly 40% of burnable fuel remainig of initial stock (I think). He continued the mission up until mid-day on May 26th, when he started the return journey to Iceland to refuel. So IMHO, fuel was not a big problem on mid-day May 24th.

dunmunro
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Re: Cover up synopsis

Postby dunmunro » Thu Dec 15, 2016 9:47 pm

Byron Angel wrote:Is there any indication as to when Leach became concerned about fuel state?
Even the difference of a few knots can make a large difference in fuel consumption when operating at high speed.

B



Leach was down to 40% fuel at ~10:00 May 24, so Leach must have concerned about fuel even then. At ~20:00 25 May PoW turned north and was in a critical fuel state (34 hours after stating 1600ton of FO available). When Leach returned to Iceland (Havalfjord) at 11:15 27 May been she was apparently down to 50 tons of fuel. PoW maintained an average of just over 27 knots from 0800 25 May to 20:00 25 May. At 2000 she reduced to 19 knots (probably to use her cruising turbines).

Byron Angel
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Re: Cover up synopsis

Postby Byron Angel » Thu Dec 15, 2016 11:15 pm

alecsandros wrote:@Cag
@Byron
Leach transmitted he had 1600tons of fuel available at 12:53 (IIRC), so roughly 40% of burnable fuel remainig of initial stock (I think). He continued the mission up until mid-day on May 26th, when he started the return journey to Iceland to refuel. So IMHO, fuel was not a big problem on mid-day May 24th.


- - -

Hi Alecs
Hopefully someone with actual service sea time can confirm/correct the following. It is my understanding that fuel state becomes a matter of concern when it reaches 50 percent; if so, then 40 percent might be described as a matter of high concern - especially if cruising in distant waters.

According to Wiki, PoW achieved a trial speed of 28 knots @ 111,600 shp with a fuel consumption of 0.73 lbs/shp/hour. Therefore, 1600 tons of fuel would have limited her to an absolute theoretical maximum of 44 hours of steaming time at 28 kts - about 1200 sea miles - disregarding potential effects of weather, sea state, and battle damage. Assuming a power/speed relationship = speed^3 at speeds > square root of waterline length, this would suggest an endurance of perhaps 1500 sea miles at the lesser speed of 26 knots.

I have a feeling that Leach would probably have felt uncomfortable with only 1600 tons of fuel remaining aboard.

Happy holidays, my friend.

B
Last edited by Byron Angel on Thu Dec 15, 2016 11:21 pm, edited 1 time in total.

Byron Angel
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Re: Cover up synopsis

Postby Byron Angel » Thu Dec 15, 2016 11:19 pm

dunmunro wrote:
Byron Angel wrote:Is there any indication as to when Leach became concerned about fuel state?
Even the difference of a few knots can make a large difference in fuel consumption when operating at high speed.

B



Leach was down to 40% fuel at ~10:00 May 24, so Leach must have concerned about fuel even then. At ~20:00 25 May PoW turned north and was in a critical fuel state (34 hours after stating 1600ton of FO available). When Leach returned to Iceland (Havalfjord) at 11:15 27 May been she was apparently down to 50 tons of fuel. PoW maintained an average of just over 27 knots from 0800 25 May to 20:00 25 May. At 2000 she reduced to 19 knots (probably to use her cruising turbines).



Hi dunmunro -
Our posts crossed, I think. Returning to port with 50 tons fuel was definitely "walking on top of the fence". God only knows what the engineering staff had to clean out of the filters afterward.

Happy holidays!

B

dunmunro
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Re: Cover up synopsis

Postby dunmunro » Fri Dec 16, 2016 2:08 am

Byron Angel wrote:
dunmunro wrote:
Byron Angel wrote:Is there any indication as to when Leach became concerned about fuel state?
Even the difference of a few knots can make a large difference in fuel consumption when operating at high speed.

B



Leach was down to 40% fuel at ~10:00 May 24, so Leach must have concerned about fuel even then. At ~20:00 25 May PoW turned north and was in a critical fuel state (34 hours after stating 1600ton of FO available). When Leach returned to Iceland (Havalfjord) at 11:15 27 May been she was apparently down to 50 tons of fuel. PoW maintained an average of just over 27 knots from 0800 25 May to 20:00 25 May. At 2000 she reduced to 19 knots (probably to use her cruising turbines).



Hi dunmunro -
Our posts crossed, I think. Returning to port with 50 tons fuel was definitely "walking on top of the fence". God only knows what the engineering staff had to clean out of the filters afterward.

Happy holidays!

B


PoW potentially lost some FO due to battle damage (~100-200 tons?) at ~0600 24 May from the 38cm dud hit that came to rest against her TDS armoured bulkhead.

Early war fuel consumption was less than in HMS Howe (reported in R&R, p.284) probably because the mid 1941 fuel was of higher quality than mid 1942 fuel. Howe's reported fuel consumption may also have been with paravanes streamed. Using Tovey's speeds and times I was able to work out that KGV's actual fuel consumption during operations against Bismarck was probably ~10% less than the clean bottom temperate water fuel consumption reported for HMS Howe. If PoW used ~1550 tons of FO from ~10:00 24 May to 11:00 27 May then she burned about 20 tons/hr on average even though she maintained 26 knots or greater for 20 hours from 1000 24 May to 2000 25 May during which time she would have burned ~650 tons of fuel.

Friedman states that KGV and PoW's trial speeds were with paravanes streamed, and without PVs trials speeds would have been ~.7 knots higher.

If PoW could have made 28.7 knots @ 111.6k shp and 228 RPM, her maximum speed, under trials conditions at the 134K shp reported during operations against Bismark would have been well above 29 knots. From 0500 to 0600 24 May, PoW averaged 239 RPM.

PoW's log seems to indicate that 220rpm = 27.2 knots and 228 rpm = 28 knots during operations against Bismarck in the open Atlantic.

alecsandros
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Re: Cover up synopsis

Postby alecsandros » Fri Dec 16, 2016 6:42 am

...

I would think about fuel state during a long pursuit with enemy beyond visual range (such as what KGV and Repulse were doing).
However, with enemy in visual range, other factors are more important, IMHO - including realy maximum speed (which is necessary to force action if that's the case).

The speed reported initialy "best speed 27", and later "maximum speed 26", shows only 1kts differential, to small to count from a fuel consumption stand point.

This correlates with Wake-Walkers comment dated May 24th 14:45PM "doubtfull is she [HMS Prince of Wales] had the speed required to force decisive action"

Byron Angel
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Re: Cover up synopsis

Postby Byron Angel » Fri Dec 16, 2016 8:31 pm

The difference in fuel consumption between 26 and 27 kts might be as much as 10 percent.

B

alecsandros
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Re: Cover up synopsis

Postby alecsandros » Fri Dec 16, 2016 9:44 pm

... Which might translate into 40 hours of shadowing left versus 44. It's to small of a difference for target in visual range.
I don't discount the possibility that Leach was somehow concerned with his 1600 tons of available fuel, but my opinion is that he would have phrased the message transmitted to the Admiralty differently , if his issue for reducing speed was fuel-concerned (and not produced by the damage suffered and/or other operational factors).

Warmest Regards old friend,


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