May 23/24 night shadowing and interception approach CS1/BC1

[Cag]

Hi All

Thanks Paul but that just confuses things more as Leach claims that PoW 284 could not bear beyond 070°. The 284 was mounted on the fore director which would mean that the director could train to a compass bearing of 020° ie directly aft as the ship was sailing to 070° or off her port quarter but not 140° which would be off her port bow?

If as we know the 284 was mounted on PoWs forward director why could it not train off her bow? Would it not be more logical to think that 020° to 140° would mean the bearings of the director ie 20° off PoW starboard bow to 140° off her port quarter? Then the fact that the director would not bear beyond 070° makes sense? (As this would be due to her formast)

Also why if Holland had sent his destroyers north and turned run a reciprocal course to that estimated that the enemy may be on would he want pow to search north east to south East if as Leach suggests they thought the enemy was north west of them?

Best wishes
Cag

[Alberto Virtuani]

Paul Cadogan wrote: "During the battle Hood bore 260 deg from PoW, so there must have been a further change to 260, or Leach's narrative is in error and the bearing was 260 from the start?"

Hi Paul,
it could well be an error, or just Leach missing to report the further change of position.


However,
could it be that the Hood "full speed" was still (despite years and wear....) somehow superior to PoW one, thus that in the minutes from 5:05 (Hood bearing 230°) till 5:55, PoW "lost" some hundreds yards and ended to a position where the bearing of Hood became 255° (as per diagram A of first board of inquiry, where the course is clearly still 300° as the A arcs are not open yet, with a line of fire 30° ahead) ?

ADM1164351diagA.jpg (40.24 KiB) Viewed 1152 times

Could it be that in the following 5 minutes until 6:00 the old "mighty" Hood was able to gain other 5°bearing on PoW, ending (when exploding) on a bearing 260° from the newest British battleship (as per Rowell map) due to her higher velocity ?

Rowell_ratio.jpg (29.21 KiB) Viewed 1152 times

Opinions are welcome, of course, as this is just a theory of mine, based on almost nothing (except the fact that Leach account of the maneuvers is quite detailed.....)


Bye, Alberto

[Cag]

Hi All

Another reason why the 284 may have not been able to bear past 070° on either beam would be the hacs tower which I totally forgot about. This would definitely block rdf transmissions directly aft wouldn't it?

Best wishes
Cag.

[paulcadogan]

Thanks Paul but that just confuses things more as Leach claims that PoW 284 could not bear beyond 070°. The 284 was mounted on the fore director which would mean that the director could train to a compass bearing of 020° ie directly aft as the ship was sailing to 070° or off her port quarter but not 140° which would be off her port bow?

Not at all my friend - it appears Leach was saying that the 284 - on PoW's forward DCT, could not bear far enough AFT beyond 70 deg true to be able to do the 20 to 70 degree true arc. It could therefore only cover 70 - 140. Unfortunately his wording made it look like he was referring to the reverse, hence the confusion.

You are correct that the HACS directors, behind the DCT would block the 284.

I suppose Holland was trying to guard against the possibility of the enemy slipping through the destroyer "net" in the poor visibility the prevailed i.e. the destroyers were searching north but the enemy might already have slipped south of them. It could also have been in response to Norfolk's fleeting sighting of a "large vessel" on an unknown course.

@ Alberto,

You pose an interesting question, regarding PoW trying to keep up with her older consort. Bruce Taylor wrote:

Then there was the "Chief" himself, Cdr (E) Terence Grogan, performing a miracle of naval engineering from the control platform of the Forward Engine Room. To this miracle the speed of his ship and the efforts of her consort to keep pace bear witness. Vice Admiral Louis Le Bailly.....

"I shall always hope that, just as he died, he became aware that the brand new HMS Prince of Wales was having difficulty keeping up with her twenty-year-old flagship as Grogan drove Hood into her last battle."

So PoW losing a little bearing (not hundreds of yards) is not impossible....but we digress.

@ Bill Jurens:

Great to hear from you sir! I have no answer for you though - I leave that to those in the know about such matters. But I appreciate that caution.

Paul

[Alberto Virtuani]

"Paul Cadogan wrote: "So PoW losing a little bearing (not hundreds of yards) is not impossible...."

Hi Paul,
we are speaking of an important interval of time (almost one hour from 5:05 till 6:00). Therefore a mere quarter knot "full speed" difference would imply 250 yards difference in the distance traveled, while a half knot would mean a 500 yards difference.

Such difference can easily account for the bearing change from 230°(05:05) to 255°(05:55) and finally to 260° (06:00) in a moment when there were more urgent priorities for Holland than maintaining PoW at a fixed distance from Hood, due to the high speed (and larger separation) of the German division.....

What is strange is that Leach accounted very precisely for the maneuvers up to 5:05 and an "ordered" change of positions would have been reported as well, while we don't have any other available in his narrative.


Bye, Alberto

[Antonio Bonomi]

Hello everybody,

@ Bill Jurens,

you wrote :

Hello Gentlemen:

I wonder if some of the confusion may lie in the mixed use of both magnetic and true courses and bearings.

The magnetic declination in the areas we are talking about seems to have been in the vicinity of 20 degrees, so the differences could be significant.

I suspect that in some reports magnetic values might have been used, but in other reports true values were reported.

This is not my area of expertise, so comments welcome...

Bill Jurens

I would definitively agree with your concerns about this possibility, ... especially on the northwards tracks starting the evening of May 23rd, 1941, ...

If only we could have put our hands on the Suffolk and Norfolk tactical maps ... as well as on the destroyers infos ... many of those questions ... probably ... would have been easily answered.

Of course we need as much as possible knowldege and expertize on this area as well as on carthography projections ... ( Mercator versus Gnomonic ) ...

https://en.wikipedia.org/wiki/List_of_map_projections

https://en.wikipedia.org/wiki/Mercator_projection

https://en.wikipedia.org/wiki/Gnomonic_projection

By the way does anybody knows which type of maps the Royal Navy was using on this area on 1941 ?
Does anybody have samples or can obtain one ?

I have puchased the Graham Rhys-Jones book, ... after Wadinga suggestion ... it is a very well done book, ... and he spent 5 pages ( from 235 until 240 ) talking about this matter, ... right on the money as far as I can tell.

Bye Antonio

[Cag]

Hi All

Thanks again Paul, its just that Leach always uses the phrase bearing when he seems to talk about compass bearings but just uses the phrase 020° to 140° in this instance which made me think, when put alongside Hollands other tactical movements, that PoW would logically search to the north west ie her green 020 to 140 or the area he thought Bismarck may be, but thanks for clearing that up.

That seems a basic mistake to make though, the rdf officer aboard Hood would have known the limitations of his own 284 as regards bearing etc (the equivalent of Paddon on PoW) maybe he was not consulted which seems odd or he was overestimating PoW capabilities especially with a massive great hacs tower behind the set!

It just seemed odd when Holland was placing his ships in a position to cut off his enemy, had turned south south West to run parallel with the course he estimated them to be on, sent his destroyers north to cover any movement south, all this appears as if Holland was convinced Bismarck was north west and yet he asked PoW to search north east, an area he was rapidly moving away from?

When PoW informed him this was not possible but 281, the longer range rdf unit, could be used he denied them the use of it perhaps for fear of its pulses being picked up. So he mustn't have been seriously thinking Bismarck was north east in the first place? Otherwise it appears that this possibility was ignored and left to chance which is not the character of Holland at all, I've studied the plotted positions as signalled and as it would have appeared to Holland and it proves he was extremely canny in his movements leaving nothing to chance.

Anyhow many thanks Paul Alberto Antonio for clearing that up I wish I could post pics as a picture paints a thousand words as they say. So PoW was stationed to starboard directly alongside Hood up to the turn to 000° (At 090° not on 090° bearing) and thereafter and onto the turn to 200° but reversed to port of Hood and was ordered to search north east (020° bearing to 140° bearing not 020 degrees to 140 degrees) in case Bismarck was behind them, got it. Leach's report was not as simple as it first seems!

Best wishes
Cag.

Best wishes

[Antonio Bonomi]

Hello everybody,

@ Alberto Virtuani,

you wrote :

Such difference can easily account for the bearing change from 230°(05:05) to 255°(05:55) and finally to 260° (06:00) in a moment when there were more urgent priorities for Holland than maintaining PoW at a fixed distance from Hood, due to the high speed (and larger separation) of the German division.....

Of course I am following close your interesting discussion with Paul and CAG about the Hood vs PoW relative bearings after every course change that morning, ... and I know you are better then me on this arguments ...

Only think I add about it is that everybody should remember that ViceAdm L. Holland, ... as reported ... gave to William Dundas the responsibility to carefully control the PoW position relative to Hood during those crucial minutes ...

Bye Antonio

[Cag]

Hi All

Hi Antonio please be assured there is no argument from my side with anyone, I'm on your side on this one I would like to defend Hollands tactics as much as you do. It was merely help I was after as it didn't seem to add up and I was feeling quite dumb!

It just appeared illogical for Holland to ask PoW to search directly aft and astern with the rdf equipment that was mounted furthest forward and for which task it was impossible for it to have done. It seemed to be doing Holland a disservice as he was a very experienced officer and if we can spot this error as lowly armchair Admirals I just couldn't believe Holland would have missed that. But I'm very willing to go with the majority on this and bow to experience.

It just seemed more logical, perhaps just to me I admit, for Hood to search ahead and a beam with her 284 and PoW to search with 284 a beam to abaft the beam ie creating an arc from the South West to North West, or where he thought the enemy to be.

To have PoW search North East to East, or in his wake and into an area he was steaming away from and leaving behind and into which the range of 284 was rapidly diminishing I just found strange as, if we give Holland the credit he is due for believing his enemy was North West of him and acting accordingly, it seems a crisis of confidence for him to search behind in his wake?

Again it was purely help I was after and again thank Alberto and Paul for their help, I'm happy to be reassured.

Best wishes
Cag.

[paulcadogan]

It just appeared illogical for Holland to ask PoW to search directly aft and astern with the rdf equipment that was mounted furthest forward and for which task it was impossible for it to have done. It seemed to be doing Holland a disservice as he was a very experienced officer and if we can spot this error as lowly armchair Admirals I just couldn't believe Holland would have missed that. But I'm very willing to go with the majority on this and bow to experience.

It just seemed more logical, perhaps just to me I admit, for Hood to search ahead and a beam with her 284 and PoW to search with 284 a beam to abaft the beam ie creating an arc from the South West to North West, or where he thought the enemy to be.

To have PoW search North East to East, or in his wake and into an area he was steaming away from and leaving behind and into which the range of 284 was rapidly diminishing I just found strange as, if we give Holland the credit he is due for believing his enemy was North West of him and acting accordingly, it seems a crisis of confidence for him to search behind in his wake?

Again it was purely help I was after and again thank Alberto and Paul for their help, I'm happy to be reassured.

Hi Cag,

Thanks for clarifying your position - I now see clearly what your thinking was and I have to say I now share your concerns to a degree. The only justification I can think of for Holland to order a radar search in the area it seems - based on our estimation of the two ships' relative positions - is to guard as much as possible against the enemy, which was still lost at that point, breaking through to the east of him, having slipped through the destroyer net and his big ships too in poor visibility. With Suffolk to the north, and Norfolk astern sweeping towards the south west, the destroyers sweeping north, he was covering all his bases the best he could.

We don't know if Hood did any searching with her 284 to the north west.

Paul

[Antonio Bonomi]

Hello everybody,

@ CAG,

not a problem at all, ... be absolutely relaxed about it, ... I fully understand your position and willingness to understand the whole manoeuvres, ... just like I do too.

I hope one day we will all able not to take " any side ", ... I am trying harder not to do it all the times, ... we should only be able to accept the facts and evidences and elaborate own opinions, ... I really hope one day we will all on the same boat ... I know it is not easy, ... but I see some very good progresses on this direction lately ...

In this regard the Graham Rhys-Jones book I purchased and currently reading ... is very well done and very fair, ... well supported by good researches, ... providing a lot of evaluations I fully agree with, ... and I am sure he cannot be accused to be a " conspirator " since he was a Royal Navy Officer ... before becoming a book writer ... and his book chapter 11 : " The search for lessons - and scapegoats " is very interesting to be read.

@ Paul Cadogan,

I agree with you, ... at that point ViceAdm L. Holland, ... looking at what he just went thru, ... did not want to run any risk to loose the enemy no matter what, ... even if I think that based on his manoeuvres he was confident on where they could have been, ... and he was right.

Bye Antonio

[wadinga]

Hello Antonio,

I am glad you have enjoyed and found Graham Rhys-Jones' book useful, as I said I think it is the best book published for some years.

On the subjest of magnetic bearings, I think this is unlikely since all the vessels were were equipped with gyro compasses. As I pointed out earlier, the strong dip into the Earth's surface at high latitudes as well as the high declination Bill has highlighted make them very little use. I recall a helmsman in a damaged merchant ship from PQ 17 giving up on steering a steady course by magnetic compass. On being complimented on his straight wake, he said he was keeping course by cloud alignment

The RN outdoubtedly used Mercator charts throughout as these are standard navigational charts. The Gnomonic business is I believe the only part where G R-J goes wrong (IMHO). Mr Alan Raven has provided a fascinating alternate explanation for Tovey's Chief Navigator's mistake in plotting Bismarck's position from D/F. The half convergency correction to allow for radio paths on Great Circles is extremely basic navigation and it is inconceivable that this mistake was made. Far more likely is Mr Raven's suggestion that the bearings were allocated to the wrong shore stations.

For the bearings recorded on PoW's action plot the distances involved are not going to make much difference in azimuth, especially given the intrinsic inaccuracy of M/F D/F. I still believe that at very short ranges, eg less than 30 miles accuracy is even lower as the powerful received signal saturates the twin dipole antenna, making an accurate null to give a bearing on a short transmission very hard.

All the best

wadinga

[dunmunro]

Thanks Paul but that just confuses things more as Leach claims that PoW 284 could not bear beyond 070°. The 284 was mounted on the fore director which would mean that the director could train to a compass bearing of 020° ie directly aft as the ship was sailing to 070° or off her port quarter but not 140° which would be off her port bow?

Not at all my friend - it appears Leach was saying that the 284 - on PoW's forward DCT, could not bear far enough AFT beyond 70 deg true to be able to do the 20 to 70 degree true arc. It could therefore only cover 70 - 140. Unfortunately his wording made it look like he was referring to the reverse, hence the confusion.

You are correct that the HACS directors, behind the DCT would block the 284.

I suppose Holland was trying to guard against the possibility of the enemy slipping through the destroyer "net" in the poor visibility the prevailed i.e. the destroyers were searching north but the enemy might already have slipped south of them. It could also have been in response to Norfolk's fleeting sighting of a "large vessel" on an unknown course.

@ Alberto,

You pose an interesting question, regarding PoW trying to keep up with her older consort. Bruce Taylor wrote:

Then there was the "Chief" himself, Cdr (E) Terence Grogan, performing a miracle of naval engineering from the control platform of the Forward Engine Room. To this miracle the speed of his ship and the efforts of her consort to keep pace bear witness. Vice Admiral Louis Le Bailly.....

"I shall always hope that, just as he died, he became aware that the brand new HMS Prince of Wales was having difficulty keeping up with her twenty-year-old flagship as Grogan drove Hood into her last battle."

So PoW losing a little bearing (not hundreds of yards) is not impossible....but we digress.

@ Bill Jurens:

Great to hear from you sir! I have no answer for you though - I leave that to those in the know about such matters. But I appreciate that caution.

Paul

Hood is recorded as having made 28.8 knots with paravanes streamed (= ~29.5 knots) during full power trials on 24 March 1941 (Briggs). According to PoW's engineering logs (G&D) PoW ran her engines up to 134k SHP "without difficulty". KGV made 28 knots with paravanes streamed with ~111.7k shp during trials (Friedman). Prince of Wales on trials achieved 28.0 knots at 111.6k shp at displacement of 42,100 tons (G&D) and this speed was probably made with paravanes streamed as per KGV, as wartime trials had to be run in coastal waters with the accompanying risk of mines.

[Alberto Virtuani]

Hi Duncan,
thanks for the info, but I would say it's always very difficult to compare speed trials data as they depend not only on the displacement, but also on the "kind" of full power used .....

E.g. for the Littorio's, a difference of almost 25000 cv of power, from normal" full power" (=134000/138000 cv used in full power trials) to "full extra-power" (=160000 cv) was calculated to correspond to a mere 0.9 knots speed increase (from 31.3 to 32.2 knots at light displacement...).

Based on the same proportion, it looks like PoW could possibly have kept up with Hood in 1941, even if with some difficulty.

However, I assume from your post that 134000 SHP was the "full extra-power" of PoW while the normal "full power" when running trials was 111600 SHP.
Do you know whether Hood was using "full extra-power" for her trials in March 1941 or just normal "full power" ?


Bye, Alberto

[wadinga]

All,

Oh No!Not battleship speed Top Trumps again, Nobody knows how fast these ships achieved on 24th May through the water because of the weather conditions. Which were different to the day they did their trials with or without paravanes , infull load, half load correctly trimmed /badly trimmed whatever. etc etc etc. Just because it says 29.9 in the log does not mean they achieved 29.9 because they have no way of measuring this. Every time they put in a sharp turn even though the engines were turning for 29.9 knots they made less because of hydrodynamic drag. The more turns the slower they went. THis is why D/R is Always wrong. That is why the the derived positions on the PoW action plot for the invisible cruisers is wrong. Nobody in PoW knew Suffolk had circled, nobody in PoW knew Norfolk had changed course. All they had were incorrect positions and reported speeds and courses. They drew straight lines and courses on their action plot because they knew no better, and Antonio has based the Diamond of Death on this and imagined M/F D/F measurements from PoW to confirm this.

Guessing whether PoW or Hood was faster on the day is irrelevent. If the the squadron commander says I am fleet guide, it is the junior ship's responsibility to maintain azimuth and distance.

All the best

wadinga