Lutjens' Intentions

Discussions about the history of the ship, technical details, etc.

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Re: Lutjens' Intentions

Post by tommy303 » Fri Jul 19, 2013 7:16 pm

Herr Nilsson wrote:
Vic Dale wrote:The grid system is not about navigation but is a method of reporting.
:clap: That was a difficult birth.
Most of the grid charts are marked at the top, für die Navigierung nicht zu benutzen
(not to be used for navigation).

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And saved the sum of things for pay.

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Re: Lutjens' Intentions

Post by Vic Dale » Fri Jul 19, 2013 7:47 pm

So possibly there is some agreement on the position of AK55 at it's center as; 57* 52' N by 35* 02' W and with it's southwestern corner at; 57* 20' by 36* 20'W.

At 0400 on the 26th Bismarck's position was 56* 27' N by 37* 55' W, or ten miles to the northwest of the position at which contact was lost, by Suffolk.

In order to make AK 55 at 0700 Bismarck would have had to steam at 28 knots heading northeast. This heading would show her to be making for the Iceland Faroes. This indicates that Lutjens wished the British to think this was where he was going, so it is likely that as his signal to Group West indicated that he was still under surveillance, he would have maintained this course for a while.

I have struck a rock as far as the diaries kept by the two survivors are concerned. I have tried to plot using the lat' and long' positions they give and it would have been impossible for the ship to have steamed between many of these positions given the times recorded. I suspect they took their information direct from the general chart which was displayed in the wardroom and probably on the main notice boards as well and this will have given only wild approximations as to the ship's true position at the given times. As I believe we now agree, a chart is no substitute for a globe. It is with regret that I suggest we cannot now use those diaries as a guide to accurately plotting the ship. I can now only use the Position Reports from British sources, the signals between Bismarck and Group West and PG's KTB.

Using the position at 0400 and steering northeast towards the Iceland Faroes Passage, Bismarck will have made AK55 at 0700. I suggest that she continued for a further hour before turning to 120 degrees. This heading was about 90 degrees to the track of PG at that time, thus drawing the enemy away from her. I suggest further that as repairs did not begin until the afternoon, that Bismarck maintained this new course at 28 knots until 1200 when may have hove to to effect repairs.

Allowing for 3 hours to complete the repairs - welding plates over the holes - the ship would have been able to move off again at 1500, resuming her heading of 120 degrees. This heading, I believe she maintained at 28 knots until 0030 on the 26th, when she altered to 150 degrees on which she continued until being relocated at 1030 that morning.

The positions and times I have used are as follows;
0400 25th - 56* 20' N by 36* 20' W
0700 25th - 57* 20' N by 35* 20' W
0800 25th - 57* 48' N by 34* 54' W
1200-1500 - 56* 48' N by 31* 59' W
0030 26th - 54* 11' N by 25* 26' W
1030 26th - 49* 38' N by 21* 11' W NB. the positions shown at 0800, 1200-1500 and 0030 are my own.

I have looked at the Grid Square calculator suggested by Tommy, but again that only finds positions on the Mercator Projections and places AK55 about 175 miles away from Bismarck at 0400, twice as far as she could steam in 3 hours. It would also place Bismarck and PG closer together than was healthy. Thanks to Tommy though.
Bismarck's Speculative Track 0700 25th to 1030 26th,.jpg
Bismarck's Speculative Track 0700 25th to 1030 26th,.jpg (97.96 KiB) Viewed 1502 times
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Re: Lutjens' Intentions

Post by Herr Nilsson » Fri Jul 19, 2013 7:53 pm

Vic Dale wrote:So possibly there is some agreement on the position of AK55 at it's center as; 57* 52' N by 35* 02' W and with it's southwestern corner at; 57* 20' by 36* 20'W.
AK55 is AK 55 is AK55 and the center is 55°03'00"N, 033°15'00"W :stubborn:
Regards

Marc

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Re: Lutjens' Intentions

Post by tommy303 » Fri Jul 19, 2013 8:01 pm

SW corner of AK55 is 54°36'00"N, 034°00'00"W

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Re: Lutjens' Intentions

Post by Vic Dale » Fri Jul 19, 2013 9:23 pm

The top left corner of AK55 as plotted using the Grid Square finder is; 55°30'00"N, 034°00'00"W

That is 145 miles away from Bismarck's plotted position at 0400. This corner is the nearest to that position and could not have been reached until the ship had steamed for five hours at 28 knots.

The only other way to get this right is to use a gnomic chart, or to find a figure for correcting the error between Mercator projections and the sphere.

Google earth does use the most up to date global positioning data, provided by the US Navy, so I we can fault it and my headings and times do add up.

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Re: Lutjens' Intentions

Post by dunmunro » Sat Jul 20, 2013 5:39 pm

Vic Dale wrote:Hi Tommy.

Image
BTW, Bismarck's maximum fuel flow was 51.1 tonnes/hr.

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Re: Lutjens' Intentions

Post by Vic Dale » Sat Jul 20, 2013 6:39 pm

Thanks for that Duncan.

I didn't know what the upper limit was. So perhaps her burn rate was slightly lower than I had thought. I noticed that Group West's figures gave her a better endurance than that I had. I may redraft that graph using the figures provided by Group West.

Btw is that long tons, metric tons or could it be cubic meters?

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Re: Lutjens' Intentions

Post by dunmunro » Sat Jul 20, 2013 8:08 pm

Vic Dale wrote:Thanks for that Duncan.

I didn't know what the upper limit was. So perhaps her burn rate was slightly lower than I had thought. I noticed that Group West's figures gave her a better endurance than that I had. I may redraft that graph using the figures provided by Group West.

Btw is that long tons, metric tons or could it be cubic meters?
I assume that they are in metric tonnes. There's more info here:

viewtopic.php?f=1&t=3153&p=36328&hilit= ... ner#p35803

I actually suspect that your figures are approximately correct and that it implies a max speed for Bismarck in the 28-29 knot range, when fully loaded. It does seem likely that there would be a substantial variation in speed and fuel consumption between Bismarck and PE and we know PE's operational fuel consumption via her war diary.

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Re: Lutjens' Intentions

Post by Bill Jurens » Sat Jul 20, 2013 10:27 pm

This is a delayed re-send (and rather substantive re-write) of something sent several days ago that apparently did not get through. I hope this one does...

Mr. Dale wrote:

"The error between the Grid Map and the globe is the reason Doenitz used the large globe for plotting his U-boats positions."

If you understand the cartographic principles by which charts and globes are created, you will soon see that there is, in practical terms, no significant difficulty in substituting a 'flat' chart for a globe. (There are many navigational textbooks showing one how to do this -- I worked through a few of them way back in the 'good-old-days' when slide-rules were still in common use. The important thing is that latitude and longitude are clearly defined; once this is done the courses and distances between the two specified points are easily determined. This is one reason why ships do not take big globes to sea with them for navigational purposes. Even a one-meter globe, which as I recall is the size Adm. Doenitz was supposed to be using, would have a natural scale of about 1:13,000,000, which is really much too small for navigational purposes.

The difficulty is that there is more than one path possible between two given points on the surface of the globe; one can take a constant (fixed) course which will always get you to the destination but which usually does not represent the shortest route, or one can take the shortest route, which requires continuous (apparent) adjustment of the course along the route. Actually, of course, neglecting the curvature of the earth, the shortest path over the surface, i.e. the so-called 'great circle' IS really a straight line. It's the curvature of the meridians which in effect makes us THINK that our path is changing.

Using Google Earth for this sort of work is more or less a waste of time. Google Earth wasn't designed for navigation, especially over long distances, it was designed to allow viewers a clear 'sensible' picture of small areas of the earth for use in local orientation. Unless you REALLY know what you are doing, you can't really do nautical navigation with it, particularly over significant distances.

In any case, I am sure that if Doenitz DID use such a globe to plot U-boat positions, the effect was intended to be more decorative than functional.

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Re: Lutjens' Intentions

Post by Herr Nilsson » Sun Jul 21, 2013 11:12 am

Vic Dale wrote: The position at which contact was lost is clearly given as 56* 20' N by 36* 20' west ...
Vic, would you agree, that this position is 4' below the upper edge of AK43?
Regards

Marc

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Re: Lutjens' Intentions

Post by wadinga » Sun Jul 21, 2013 11:31 pm

All,

Despite all this misdirection about how far north Bismarck went during her successful evasive manoeuvre and kind attempts to remedy shortcomings in the understanding of nautical charts, there is not a shred of evidence Bismarck was headed anywhere other than France. To confirm this, even when spotted first by the Catalina, then Ark Royal's Swordfish shadowers and finally by HMS Sheffield as well, Lutjens stolidly maintains course for France occasionally making slight turns to port after his diversion south and his speed rarely exceeds 22 knots. If his bows were actually repaired (there is no evidence they were) and if he truly was not short of fuel he would have opened the taps and got there ASAP. Here are the B-Dienst intercepts available on this very website:


1301B/26.5. Von qj2 = Ark Royal an gzz = (Cleethorpes). O U
Estimated position, course and speed enemy battle ship at 1215B 49º 10' 20º 10', course 110º, speed 20 knots, Ark Royal aircraft in touch. My position, course and speed at 1248B 49º 30' 19º 10', course 350º, speed 15 knots, torpedo bomber strike at about 1500.
1520B/26.5. Von qj2 = Ark Royal an gzz = (Cleethorpes). O U
My (your) 1301. Estimated position, course and speed enemy at 1500 (48º) 24' 18º 46', course 110º, speed 25 knots. My position, course and speed at 1515B 49º 14' 18º 19', course 110º, speed 26 knots. Striking force left 1500B.
1700B/26.5. Von qj2 = Ark Royal an gzz = (Cleethorpes). O U
My 1520B. Estimated position, course and speed at 1630B, (48-49º) 12' north 17º (?) 34' west, course 110º, speed 25 knots. My position, course and speed at 1700B (50º?) 00' 17º (?) 25' X 15, course 140º, speed 26 knots, striking force searching enemy.
1800B/26.5. Von qj2 = Ark Royal an gzz = (Cleethorpes). O U
My 1711B. Estimated position, course and speed enemy battle fleet at 1800B 48º (?) 06' etwa 17º 02', course 110º, speed 22 knots. My position, course and speed at 1810B (48º) 55' etwa 17º ..', course 140º, speed 29 knots, striking force scored no hit and leaves .. at 1830 above position based on fix at 1500B.
1950B/26.5. Von qj2 = Ark Royal an gzz = Cleethorpes. O U
My 1800B. Estimated position, course and speed at 1900B (48º) 00' 16º(?) 28', course 110º, speed 22 knots. My position, course and speed (48º) 36' etwa 16º? 54', course 110º, speed 29 knots. Striking Force .. . Above position besed on fix at 1500B.
2140B/26.5. Von qj2 = Ark Royal an gyd2 = Horsea. O U
Estimated position, course and speed of enemy were at 2130B 47º 45' 15º 25', course 330º, speed 22 knots. My position, course and speed at 2100B (48º) 17' 15º 50' (west of), speed 20 knots.

All the best

wadinga
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Re: Lutjens' Intentions

Post by Vic Dale » Tue Jul 23, 2013 8:16 am

So it seems there is no difference between the globe on which we live and on which ships sail and the Mercator's projection which is the basis of naval charts.

The Mercator's projection is a cylindrical representation of the globe which is true more or less at the equator, but which has increasing error top and bottom and cannot give a totally accurate position simply by marking off the lat' and Long' coordinates on such a chart. Mercators Charts only work on the small scale. Like sticking postage stamps over the surface of a football the error between each is small and they have to be fiddled together to make them fit, but try to use a whole sheet of paper to wrap a ball and it will have to be crumpled. It is impossible to transfer a sphere to a flat object and vice versa

A Mercators global chart has the same sized gradations for degrees longitude at the Equator and at the North and South Poles, so there will be very great error in placing a line of at 45 degrees across the Atlantic. On the globe it will point to one place and on the chart it will point to quite another, so a correction must be applied. Using a globe at U-Boat headquarters would permit rapid assessment of convoy sightings and the position of U-Boat patrols, making it easier to get the big picture.

I have not for as single moment suggested using a globe to navigate and nor do I suggest using Google Earth for navigation either.

I have used Google Earth to show what was happening on the globe and have demonstrated that it is not possible to use Mercator's projections in conjunction with it. It was the attempts to use the U-Boat Grid Map and lat' and Long' coordinates which had been taken direct from a Mercator's chart, to fault my findings which was causing the problem. I have shown that the two things; Mercator and Google earth cannot be mixed. I have therefore had to rely only on noon sun sights and some Grid positions which have first been corrected to conform with Google Earth.

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Re: Lutjens' Intentions

Post by Vic Dale » Thu Jul 25, 2013 9:46 am

I don't know if people are ahead of me on this, but it seems the grid calculator does work if you just put the grid square number in and let it give a position lat' and long' on Google earth. I have plotted 3 separate grid squares and they match the positions at which given events and sightings are recorded and it's many thanks to Tommy for giving us the link.

My mistake was trying to use the U-Boat Grid Map to find a position and then trying to use that to find a grid square. It is not possible to use the Grid Map in conjunction with Google Earth, but as the Grid squares work, I think there must be a cleaver bit of software doing the complicated calculation for error between Mercator and the Globe.

I am wondering now if it would be possible to use the positions recorded in the prisoner's diaries to track back on the U-boat Grid and get a grid square for each of them. If so I may be able to get a position form the calculator. That might take some of the mystery out of Bismarck's whereabouts between 0306 on the 25th and 1030 on the 26th

So certain am I that this grid calculator is working properly, that I have now ruled out the northeast heading after the loss of contact at 0306. There was an error which I had inadvertently factored in and was about to raise with everyone. It concerns the report of the ship being in AK55 at 0700. Ship's clocks were one hour behind those in the British ships, so that signal was sent at 0800 and not 0700 as recorded. That leaves 4 hours to steam 157nm to reach that square. It's not nearly enough, because Bismarck would have to have steamed at 39 knots between 0400 and 0800. So confident am I in the U-Boat Grid calculator that I am going to suggest that the track chart showing the ship turning to the west, north and north east over the course of an hour is wrong. I now think it was done much faster than that.

I now believe that as Suffolk turned onto the outer leg of the zig zag, Lutjens immediately increased speed and turned the ship north, using the enemy's speed in conjunction with his own, to open a large gap. With Bismarck heading northwest and Wake-Walker heading southeast at a combined rate of nearly 60 knots the gap would have been beyond Suffolk's estimated radar range of 35km in just a few minutes, then a rapid turn to the east and later southeast to shape course for Ferrol in Northern Spain. Lutjens was now to the northeast and astern of the British squadron and rapidly opening the distance between himself and PG who was heading south. The maneuver has completed without the need to engage PoW.

The ship must have continued at high speed to make the dash southeast and make that square by 0800, but it could just be done in five hours.

The heading to make that square in the allotted time was Ferrol In Northern Spain, I need to try and make sense of the 150 degree heading at 1030 the next morning which had the ship pointed toward North Africa.

Anyway it looks like Google earth is going to give us some accurate answers despite what has been said.

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Re: Lutjens' Intentions

Post by Pandora » Thu Jul 25, 2013 11:24 pm

Vic, what would be the point of going to neutral Spain?

Bismarck would then be interned for the rest of the war, or I am missing something...

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Re: Lutjens' Intentions

Post by Vic Dale » Fri Jul 26, 2013 10:29 am

To Pandora.

Northern Spain Was recommended by Group West because Franco was was a Fascist and although ostensibly neutral was friendly with Hitler. U-boats often made for Vigo to oil and their depot ships often oiled and resupplied there. Under Maritime Law, ships from belligerent nations could oil and make sea worthy, though they could not purchase ammunition, arms, make repairs to their armament, or improve fighting efficiency. Northern Spain Was a handy location from which to make for Brest and any of the French Atlantic ports. No attack could be made on a vessel moored in Spanish waters, though all adjacent waters were subject to overflight from the Luftwaffe. Over flight by the RAF could only be achieved with difficulty with a hazardous flight over the sea, or over occupied France.

When establishing the cross over patrols at the entrance to the Biscay, a Senior RAF officer form Coastal Command, who had served in the Merchant Navy, reasoned a ship making for the French Biscay coasts would make it's landfall on Ferrol, before heading to it's intended destination. Through his experience, he learned that the rocky French coasts could be hazardous after a lengthy trip across the Atlantic, whereas a landfall on Ferrol would permit a fast passage on a clear track direct to any of the French harbours.

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