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Author Topic: Chatham Dockyard Defence  (Read 10551 times)

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Offline Bilgerat

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Re: Chatham Dockyard Defence
« Reply #11 on: July 24, 2010, 12:56:54 »
The reason that there was a delay in fitting the 4.5" gun to destroyers is actually quite brutal. Destroyers were regarded by the Admiralty as almost 'disposable' warships and were felt to be a lower priority than fitting the guns to Capital Ships.

The 'Z' class were the first destroyers to receive the 4.5" gun. Before that, that particular gun had been fitted as main anti-aircraft guns on the Illustrious Class and Implacable Class aircraft carriers (16 guns each) as well as HMS Ark Royal (16 guns). It was also fitted as main armament to the 2 modified Dido Class Anti-Aircraft Cruisers HMS Scylla and HMS Charybdis (8 guns each), as well as secondary armament aboard the re-built Queen Elizabeth Class battleships Valiant, Queen Elizabeth and Warspite, in addition to the rebuilt Renown Class Battlecruiser Renown, all with 20 guns each. It proved to be a very effective anti-aircraft gun, in particular aboard HMS Scylla, known in the fleet as the 'Toothless Terror'. No capital ship (Aircraft Carrier, Battleship, Battlecruiser or Cruiser) fitted with this gun was lost to air attack.

All these ships had their 4.5" guns fitted in pairs, whilst the destroyers had single mounts, like HMS Cavalier.

The 4.5" gun was actually a better gun than the 4.7" it replaced. As well as a higher elevation, it also fired a heavier shell over a longer range. The same 4.5" gun, mounted in the semi-auto mk6 turret saw service for a long time. It was fitted to all the 50's and 60's built frigates and destroyers and saw action as recently as the Falklands War.
"I did not say that the French will not come, I said they will not come by sea" - Lord St Vincent

Andrew401968

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Re: Chatham Dockyard Defence
« Reply #10 on: July 19, 2010, 20:39:42 »
Hi, and hello all, this is my first post.

I noticed a few mistakes with Otis earlier posts.

The photo isn't the QF 3 inch 20 cwt AA gun, but a 12 pounder 12 cwt on a High Angle mounting. At first glance, they appear to be the same, but when you take a closer look, you can see the differences. Key differences, is the shape of the barrel, on the 12 pounder, the barrel as a step, where it narrows, whereas the 3" gun is tapers smoothly to the end. The cradle and recoil mechanism is significantly different too, on the 12 pounder, its underneath, and you can clearly see the distinctive diamond shaped front plate. On the 3" gun, the recoil cylinders are short and located above the breach, and there is also quite a complex mechanism for the sight apparatus.

Essentially, the 12 pounders were originally a low angled weapons placed on HA mountings to provide a dual purpose weapon for ships, during WWII they were used as the principle armament for auxiliary ships, but sometimes on smaller escorts, usually as a result shortages. HMS Cambeltown was armed with one for the The St Nazaire Raid. The QF 3" 20 cwt AA was a purposed designed anti-aircraft gun, and is significantly larger than the 12 pounder. Another similar looking gun, is the various marks of the 4" HA Gun. Wikepedia as a good page on both the 3" and 12pdr

http://en.wikipedia.org/wiki/QF_3_inch_20_cwt
http://en.wikipedia.org/wiki/QF_12_pounder_12_cwt_naval_gun

The other partial error was the reference to the 4.5" gun being the armament of fitted "to most destroyers of the time". This was true only from late 1944 onwards when the first Z class destroyers came into service, the majority would have been armed with 4.7" calibre  guns or 4" guns (rare on Fleet Destroyers). The 4.5, apart form its use by the army, was used on aircraft carriers and many capital ships, particularly those modernised in the interwar period, such as HMS Renown, in twin mountings.

This is significant, because one of the key weakness of Royal Navy Destroyers, was the lack of an effective HA version of the 4.7", especially when compared to the DP 5" gun of the USN. I've tried to find out why they delayed switching to the 4.5 gun, with was a more effective DP weapon, perhaps shortage of production or priority to army production, but I think the main reason may have simply been conservative inertia resisting change.

Offline kyn

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Re: Chatham Dockyard Defence
« Reply #9 on: August 24, 2009, 11:36:31 »
A similar structure to the Flak Towers can be found at the Lea navigation at Waltham Abbey, this photo was sent to me by Alec beanse.

Offline kyn

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Re: Chatham Dockyard Defence
« Reply #8 on: August 12, 2009, 15:25:19 »
Each Company possessed the weapons as follows:  2 mobile A/T Smith guns; 3 static A/T Mortars; 1 A/T rifle; 2-3 heavy M/Gs; approx. 1 rifle & 1 sten gun peer man.
Ammunition: Ball ammunition; A/T shells Mortar bombs; Anti-personnel grenades which were stored in strong rooms, 1 to each Coy.  
Bofors batteries were mounted in various parts of the Dockyard, manned by R.A. personnel.  In the event of guns being put out of action R.A. personnel came under the command of Home guard Company Cdrs. in whose area they were based, and assumed an infantry roll.
Each Home Guard Co. was organised in mobile and static platoons, trained to act as independant units, under a general directive.  Signal sections were equipped with field telephones and a few 'walkie-talkie' sets.

rossco

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Re: Chatham Dockyard Defence
« Reply #7 on: August 12, 2009, 08:03:11 »
I wonder if this had anything to do with it: http://www.medwaymemories.co.uk/borstal_gun.htm

Isnt the gun on the railway wagon still in the dockyard or is that a different one from elsewhere?

Offline otis

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Re: Chatham Dockyard Defence
« Reply #6 on: August 11, 2009, 22:34:18 »
A report existes that an AA gun (type unknown) was set up on a railway wagon, protected by 2.5' armour plate, propelled by a steam engine around the yard to provide a mobile defence.

HMS Arethusa
An AA Light Cruiser, was present in the Yard in early 1940 and, whilst in dry dock, used her guns against aircraft approaching up-river.  She had to be specially shored up to prevent hull damage.  She was later moved up the Thames for the same purpose.

More info to come...

Ahh ! A railway gun ( of sorts ). Perhaps that was called Big Bertha as a joke ?

Read about that Cruiser story some time ago. Failed to remember it's name.  :-[

Good stuff, waiting for more.......  :)

   regards Otis
"there was more hit than miss about this arbitrary bombardment"

Offline kyn

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Re: Chatham Dockyard Defence
« Reply #5 on: August 11, 2009, 21:55:07 »
During 1939-41
In the late months of 1939 sandbagged machine gun emplacements were built on the roof of the Royal Marine Barracks in Dock Road, adjoining the Dockyard.  These were equipped with Lewis Machine guns of WWI vintage, and were therefore only intended for immediate and low level attacks.  A mobile 3" AA gun (possibly a battery, as part of the GHQ Line Anti Invasion Defence System was set up on the Great Lines for a short period to cover air approaches from the East.

From 1939-41
A 3" gun was set up on Thunderbolt Pier in the Medway by No.2 Covered slip, and was manned by volunteers from No.1 Machine Shop prior to the formation of the LDV/HGF.
A report existes that an AA gun (type unknown) was set up on a railway wagon, protected by 2.5' armour plate, propelled by a steam engine around the yard to provide a mobile defence.

HMS Arethusa
An AA Light Cruiser, was present in the Yard in early 1940 and, whilst in dry dock, used her guns against aircraft approaching up-river.  She had to be specially shored up to prevent hull damage.  She was later moved up the Thames for the same purpose.

More info to come...

Offline otis

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Re: Chatham Dockyard Defence
« Reply #4 on: August 11, 2009, 17:46:15 »
Thanks Kyn, that was quick, and a map too ! Fantastic.

It all fits nicely as the 40mm Bofors was the modern replacement for the Pom-Pom. My light flak was only researched up to May 1941.

Home Guard units were introduced into AA Command at the end of 1942. So guns under RA control were indeed manned by Home Guard. It appears that AA gunners were at the bottom of the Army pile anyway, and often got the sick and the lame. So Home Guard were considerered up to the task.

I bet the Navy had their own weapons too. Either fixed on land or something moored in the river. Any further info greatly appreciated.  :)
"there was more hit than miss about this arbitrary bombardment"

Offline kyn

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Re: Chatham Dockyard Defence
« Reply #3 on: August 11, 2009, 17:11:05 »
"Within the 'Yard three 'Flak Towers' were built: by No.3 Basin, behind No. 7 Dock and behind the factory on Upnor Wall.  Each equipped with a single Bofors 40mm gun.  these towers were manned by R.A units at first, and then (although opinions differ) by Dockyard Home Guard (31st Btn.).  They were demolished post WWII c.1950.  (N.B. A surviving tower of the same type may be seen at the approaches to Kings Hill at West Malling)."

Taken from Chatham Dockyard in World War Two ( A Chatham Dockyard Historical Society Research Paper No. 20)

Offline otis

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Re: Chatham Dockyard Defence
« Reply #2 on: August 11, 2009, 15:50:45 »
.....switches notes....

In addition to the smaller calibre weapons installed to defend this "Vital Point", the Dockyard also fell into a "Gun Defended Area" guarding the eastern approaches to London. The belt known as Thames and Medway ( South ) comprised 72 of the heavy AA guns in August 1940. These covered an area along the river from Dartford to Sheppy, in batteries of often 4 weapons, made up of the following...

8 x 3 inch AA ( as before but with sights designed for higher altitude work )

8 x 3.7 inch (mobile). The modern Army AA gun. Mounted on wheels like the famous German 88.

24 x 3.7 inch (static). These were static versions to save on costs.

32 x 4.5 inch. These were a Navy weapon as fitted to most destroyers of the time. Each gun was mounted in a turret, giving the same appearance as a destroyer turret.

These being mounted in groups of 4 are unlikely to be called the "Big Bertha". I did plot all the known sites on a map a while ago, I could be wrong, but don't recall one in the Dockyard ?

By 1944/45 the aerial threat had changed from Luftwaffe aircraft to V1 flying bombs. Thames and Medway ( South )
comprise the same number of heavy guns. 64 of them were the 3.7 inch guns and 8 or 9 were the new 5.25 inch weapons.

These new heavy guns were fitted to cruisers as a heavy AA weapon, and were fitted on ships and on the ground as a twin barrelled pair in a large round turret.

Again, big weapons, but can't see a battery of 8 barrels in four turrets being called "Big Bertha"

These are the Army weapons. I have no idea and would love to know what Navy weapons may have been present. Britain was desperate for weapons in 1940, and I can imagine all sorts of obolete guns being dusted off and pointed skywards.

Kyn, do you have any info or pics of those flak towers ? I had no idea they existed.



This is a pic of the QF 3 inch, 20 cwt AA gun. For land use they were most often without the sheild.
"there was more hit than miss about this arbitrary bombardment"

Offline otis

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Chatham Dockyard Defence
« Reply #1 on: August 11, 2009, 15:25:49 »
I did some research on UK anti-aircraft for a project I am involved in. The "Big Bertha" in another thread caught my eye.

In August 1940 the Dockyard was credited with 5 of the First World War vintage 3 inch anti-aircraft guns and 17 Lewis machine guns. These were crewed by the 6th Anti-Aircraft Division of the Army. These 3 inch weapons stood about as tall as a gunner, and were the smallest of the heavy AA guns available. Not a "Big Bertha".

By November 1940, the pace of the Battle of Britain had changed the requirements. The allotment then was only 2 of the 3 inch heavy weapons, with 28 Lewis guns and 3 of the new 20mm Hispano Suiza cannons. The later were effecively a slower-firing scaled up machine gun firing a bullet that exploded inside the aircraft.

In May 1941 the Dockyard had lost the last of the obsolete 3 inch guns and now had only 16 Lewis guns, 5 of the 20mm cannons. She had gained 4 of the 2 pounder Mk VIII twin weapons. Commonly known as a "Pom-Pom" these were 40mm cannons that were fitted to most Destroyers as above as a close range rapid fire weapon.
"there was more hit than miss about this arbitrary bombardment"

 

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