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The Sailor
21-02-2008, 04:59
The Hedgehog was an anti-submarine weapon developed by the Royal Navy during World War II, that was deployed on convoy escort warships such as destroyers to supplement the depth charge. The weapon worked by firing a number of small spigot mortar bombs from spiked fittings. Rather than working on a time or depth fuse like depth charges, the bombs exploded on contact and achieved a higher sinking rate against submarines than depth charges did.

The major deficiency of the combined ASDIC / depth charge attack was the so-called blind time, which was the time it took the depth charges to reach the set depth at which they were to explode. This time increased with the presumed depth of the contact, and could often result in the submarine evading the attacks.

Further, it was related to the method of attack used by single destroyers. They would acquire a target, with ASDIC, then head toward the contact at speed. However, at a certain distance, the target would be too close to be spotted on ASDIC, which the submarine, again coupled with the problem of the slow-sinking depth charges, could use to avoid the attacker, since the attacker would need to speed up to minimize the time between loss of contact and attack which the submarine could hear if it had not yet picked up the destroyer.
The Hedgehog could fill this gap.

Hedgehog was a 24-spigot mortar of crude build, usually firing to 300 yds or around 250 meters ahead of the attacking ship, shortly after blind time began. It fired a circle-formed salvo in the general area of the submarine, each spigot containing 35lbs of Torpex. The spigots were contact fused, thus only creating the disturbing noise of depth charge attacks when actually hitting a submarine, which was as good as a kill though surfacing damage was possible too. It is not known that any submarine survived a hedgehog hit because no one lived to tell about it.

During 1943, it came as a shock to a U Boat crew to hear the acoustic approach of a destroyer and suddenly find themselves blown up and sinking before the ship even reached them.

The beginning of the end in the Battle of the Atlantic.

The Hedgehog fired twenty four 14.5 kg charges whereas a later development called the "Squid" fired more. A further development called "Limbo" was used into the 1960s, and this used 1 ton charges.

TheDigger
21-02-2008, 12:18
Interesting weapon the Hedgehog I wonder what the firing rate of this weapon was. Was this equipped in a bank of more than one, does anyone have any pictures of ships fitted with this device.

TheDigger
21-02-2008, 12:23
Well I could not wait and did a little research

The first Hedgehog installation was put onboard the frigate (DE) HMS Bayntun on March 12, 1943.


I found a pic of a dual setup so this got over some of the relaoding issues

John Brown
21-02-2008, 13:26
The 'SQUID' which replaced the hedgehog was a three barrelled mortar system which fired depth charges ahead of the ship in a triangular pattern. (On the face of it, the return to depth charges seems a bit of a retro step other than the fact that they are fired ahead of the ship). As with the hedgehog two squids could be mounted to give a salvo of 6 charges. The first squid was rushed into service in May 1943 on HMS Ambuscade with the first production unit being fitted on HMS Hadleigh Castle. HMS Salisbury was the last ship to fire a Squid in Royal Navy Service in 1977.

Stan.J
21-02-2008, 19:13
H.M.S.Magpie was one of the early ships to be fitted with Hedgehog. accounting for the destruction of U238 on 9/2/1944. Looking at this picture the weather was often the worst enemy on Arctic conveys.

tomsam
24-02-2008, 00:43
Hi John.
I am sorry to correct you but you are thinking of a Mk 10 "Limbo" Mortar.
But they were developed from the Squid.Some Squid were fitted forrard and some aft, but all Limbo's were fitted aft in echelon .
Hope this helps.
Tomsam

John Brown
24-02-2008, 11:53
Hi Tomsam

In the interests of accuracy I am always ready to be corrected. On this occassion however, I am not sure what you mean. Yes, the Limbo was a further development of the Squid but as far as I am aware my post gave info on the Squid itself. If you know differently please could you explain further?

Regards...John

Batstiger
24-02-2008, 12:21
Yes John that is correct you only mentioned the Squid in comparison with the Hedgehog.
The Squid was a far more advanced weapon as opposed to the Hedgehog. With the latter contact with bomb and submarine had to be made before it was successful, the other bombs would explode in sympathy otherwise the whole lot was wasted.
With the Squid a depth setting was being applied all the time up to the moment of firing by electronics from the Asdics. these came from a "Q" transponder and the "147" depth recorder.
When fired all charges would explode on reaching the Submarines last known depth.
As regards the Limbo, this did not come in to use until after the war.
The first ship I came across that was fitted with a single triple mounting was the Weapon class destroyer HMS Scorpion.

Bob.

tomsam
24-02-2008, 13:45
Hi John, Sorry if what I said was unclear. I was referring to HMS Salisbury being the last ship to fire Squid in service in 1977. When I wrote the first reply I had a momentary lapse of reason and forgot that the Salisbury class were never fitted with the limbo as the expense was too great for Air Direction Frigates (Not being ASW Frigates ) Again sorry for the confusion as all what you posted was pertinent and my brain needs "paying off".:o
Regards
Tomsam

John Brown
24-02-2008, 20:00
No problem Tomsam. Just glad it's cleared up now.

Bob...thanks for your input too.

Regards...John

Batstiger
24-02-2008, 23:14
Your welcome John, I used to be a Ping bosun many years ago.

astraltrader
09-09-2009, 18:25
I thought this classic picture of a Hedgehog anti-sub mortar might prove to be of some interest?

Scurs
09-09-2009, 19:55
Were we (SURPRISE) the last ship to be in commission with Hedgehog fitted? In 1963, someone (probably the skipper) got the bright idea to fire it...............er.............not an all together unqualified success! The Hedgehog was mounted in 'A' Gun position.
The 24 bombs ("lights" of course - no warhead) performed something like:-

6 didn't go anywhere, stayed on the mounting
10 fired and bounced off the foc'sle
3 lodged by the breakwater
5 went as designed

We also had an twin 4" gun, and two army style, hand powered, Bofors..........nobody was brave enough to attempt to fire those.
The Hedgehog experiment was not repeated, and may have been the last time one was fired in the RN, but any submarine would have been perfectly safe! :rolleyes:

astraltrader
09-09-2009, 20:00
It was proven to be far more accurate than depth charges once the initial teething troubles were resolved.

Apparently a copy of Hedgehog was produced in Russia known as the MBU-200 which developed in 1956 into the MBU-600 with an enhanced range of 600 metres or so....

tim lewin
10-09-2009, 05:26
Posted before but no harm in repeating in this context; all from the 55'56 commission of Corunna and taken in the Med; probably Ron can add detail.
tim

Squid, not h/hog or limbo

tim lewin
10-09-2009, 09:35
Should have posted those in reverse order! someone was asking about p/vane stowage (vertical on q/deck) if you close-up on the stern view you can see it triced up to the bulkhead.
tim

tone
12-09-2009, 18:01
The fact that hedgehogs only exploded on contact was a virtue, not a fault. Along with (of course) the ahead-firing aspect of these weapons, the idea was to exchange the few large area weapons that were depth charges with many smaller weapons that only fired when a hit was obtained. This meant that the escort team wasn't deafened and the waters roiled for minutes on end by explosions which may not accomplish any damage anyhow.

The hedgehog/mousetrap only caused a smaller loss of sonar utility in the event of it actually achieving something. Moreover, the explosion (or lack thereof) was itself of foreensic value.

I'm sure the squid was a good weapon, as well, but its charges' larger radius of destruction were obtained with a cost. I'm curious how the approaches compared in net results.

tone

qprdave
12-09-2009, 18:14
I posted this link in the pingers thread it gives you the kill rate v attacks of all the A/S Weapons

http://www.navweaps.com/Weapons/WAMBR_ASW.htm

starshell
13-09-2009, 11:42
Just a bit of clarification on the early development of Hedgehog.....

Early trials with the Hedgehog mounting were taking place by August 1941 on the old W Class destroyer Westcott and by September 1941 full sea trials were taking place using Westcott and Enchantress. Westcott apparently scored one of the first kills using Hedeghog on 2nd Feb 1942, sinking U-581 (Note that every source I have read on this sinking has a different account - some say just depth charges were used, one says ramming and two say hedgehog! ). By the end of 1942 over 100 ships carried Hedgehog. On smaller escorts like the Flowers and Sloops the Hedgehog was split into two units firing 12 spigots each. RN crews were quite wary of Hedgehog due to initial mistakes in installation, a general lack of maintenance information and no manuals, but when used properly in a deliberate attack they could be quite efficient and achieved a 35% successful attack rate by late 44 (based on 37attacks and 13 successes).

On 20th September 1943 HMS Escapade was unlucky enough to be the only RN ship heavily damaged by its own Hedgehog unit. Escapade had stopped to assist the frigate Lagan which had just had its stern blown off by a homing torpedo. On locating the U-boat responsible and firing her Hedgehog the bridge crew of Escapade witnessed a massive explosion above the bows. One of the bombs had exploded permaturely when leaving its spigot. This practically blew off the bow of the ship and there were 16 dead plus nine injured. Amazingly she still managed to tow the battered Lagan back to Northern Ireland and Escapade was then repaired at Portsmouth later that month. Lagan and Escapade must have been a grim and bizarre sight as they pulled into port together!

The USN used Hedgehog more widely and had more success with it. In May 44USS England famously sank 6 Japanese submarines with 12 salvoes in 11 days.

Mark

Forester
16-06-2010, 12:12
I have a collection of first hand reminiscences by crew members of HMS Forester (H74) and they describe in some detail a split hedgehog system installed in their ship. There was a 12 spigot mortar on each side of the forward superstructure and the crew's action station was in the shelter below the 'B' gun's blast shield and aft of the 'A' gun, which remained installed on the fo'csle. The two mortars were fired simultaneously with 12 of the 24 round salvo going from each side to make a complete pattern. The mortar bombs came up from the magazine in boxed sets and the boxes had to be stowed on deck after use, to be returned empty when they returned to port. I've never seen any pictures of such an installation, but the two crew members who tended and fired this set up gave such detailed descriptions that you can't really doubt them.

r.morrison
16-06-2010, 13:50
The idea was succesful by all accounts then, the Russian Navy still use a similar system to this day. (Photo shows UDAV system on KUTZNETOV on the lower left........)

Were there are accounts of the British system having been mounted on bren carriers during WW2 for use against ground targets ?

I did read this somewhere:)

chris westwood
16-06-2010, 16:18
Yes John that is correct you only mentioned the Squid in comparison with the Hedgehog.
The Squid was a far more advanced weapon as opposed to the Hedgehog. With the latter contact with bomb and submarine had to be made before it was successful, the other bombs would explode in sympathy otherwise the whole lot was wasted.
With the Squid a depth setting was being applied all the time up to the moment of firing by electronics from the Asdics. these came from a "Q" transponder and the "147" depth recorder.
When fired all charges would explode on reaching the Submarines last known depth.
As regards the Limbo, this did not come in to use until after the war.
The first ship I came across that was fitted with a single triple mounting was the Weapon class destroyer HMS Scorpion.

Bob.
I was under the impression that the fact that the hedgehog bombs didn't explode unless a contact had been made was considered an advantage, because it confirmed that a contact had been hit, altough I appreciate that a near miss from an exploding depth charge coiuld damage a submarine badly.
Thanks for the description of how a squid worked, really interesting.

John Brown
16-06-2010, 16:37
Were there are accounts of the British system having been mounted on bren carriers during WW2 for use against ground targets ?

I did read this somewhere:)


I'm not sure about being mounted on Bren Carriers but certainly a variant, the Hedgerow, was carried in some landing craft and used to explode mines on the beaches during the Normandy landings.

Regards...John

Forester
18-06-2010, 07:41
I was under the impression that the fact that the hedgehog bombs didn't explode unless a contact had been made was considered an advantage, because it confirmed that a contact had been hitWhen Forester and Vidette were dispatching U413 in the Channel Forester's salvo produced two explosions but the ASDIC continued to track the submarine and Vidette hit it again with the reuslt that the one survivor burst to the surface in a huge bubble of air. It seems that in the shallow water close to the coast two of Forester's hedgehog bombs exploded on contact with the seabed.

Re: hedgehog on land, some Matilda Mk II tanks were equipped with a seven round hedgehog mortar.

chris westwood
18-06-2010, 13:28
When Forester and Vidette were dispatching U413 in the Channel Forester's salvo produced two explosions but the ASDIC continued to track the submarine and Vidette hit it again with the reuslt that the one survivor burst to the surface in a huge bubble of air. It seems that in the shallow water close to the coast two of Forester's hedgehog bombs exploded on contact with the seabed.

Re: hedgehog on land, some Matilda Mk II tanks were equipped with a seven round hedgehog mortar.

thanks mate

barnsey
25-06-2010, 10:06
Posted before but no harm in repeating in this context; all from the 55'56 commission of Corunna and taken in the Med; probably Ron can add detail.
tim

Squid, not h/hog or limbo

This is a great thread and these photos Tim are very interesting as well as being detailed....

thanks everyone

Alandc
26-05-2011, 10:15
With regard to Starshell's post (#19) and whether the first "kill" using a hedgehog was by HMS Westcott, my father served as a signalman on HMS Westcott from 31st Oct '41 to 23 Dec '42 and he was in no doubt that U581 was rammed. He didn't speak much about his wartime experiences but that is one I do remember. It also tallies with the account in Tom Chapman's book of HMS Wescott (Water, Water, Every Where). My father also kept a newpaper cutting from the time that refers to the ramming and which I've attached - plus some photos that I believe are the survivors being picked up.

Alan

alan reeves
27-05-2011, 20:07
[QUOTE=The Sailor;5333]ThAlane Hedgehog was an anti-submarine weapon developed by the Royal Navy


Am i right in believing the hedgehog bombs had a impeller on the nose and as the bomb went through the air the primer was screwed into the charge.We had the weapon on the St AustellBay and when ammunitioning ship, one of the stokers was playing with it making it fly round. Alan.

jainso31
29-05-2011, 17:49
Alan- none of the photographs in this thread, show an impeller on the nose ,as you put it; it had a contact fused warhead and was fired in batches.

jainso31

qprdave
29-05-2011, 18:20
no impeller/propeller. As Jim said it was a contact weapon. But.... They were fired so that if one went off the others detonated as well

Dave

Scratcher
30-05-2011, 14:05
Hedgehog Bombs with what look like impellers to me?.

qprdave
30-05-2011, 14:39
The impeller shown had nothing to do with depth finding, it was used as a screw type mechanism to fuse the projectile down to prime it. If it hit a target before it completed the fusing, the only bang you would have heard is it hitting the submarine and there would be very relieved submariners.

Dave

alan reeves
30-05-2011, 18:14
Thanks QPRDave. Does this mean if the fuse was manually screwed home and the bomb dropped on deck it would explode?

qprdave
30-05-2011, 19:09
I should imagine it wouldn't be advisable to mess with it. And if you did. Don't drop it!!!!!

Dave

Blaydon
30-05-2011, 22:16
From what I have heard there was a Hydrostatic component to the fusing and although the vane would screw the pistol home the weapon was required to descend to a depth of 15 feet prior to it being fully armed.

Forester
31-05-2011, 06:47
I should imagine that the impeller was a modification to the early bombs. designed to prevent premature detonation in the event of a bomb failing to be thrown clear of the ship, as happened a number of times - most spectacularly to HMS Escapade.

Don Boyer
31-05-2011, 07:13
Very interesting thread this, as I had not heard or read much of the early development of this weapon. I do know it was a very effective piece of work, as the US Navy was all over it as soon as it was invented and it sprouted on destroyers and destroyer escorts just as fast as they could get them manufactured.

The US destroyer escort England's famous sortie against the Japanese navy in 1944 generated six submarine kills in 12 days, all the kills being made with Hedgehog. She was working a Japanese submarine scouting line revealed by code-breaking and managed to pick up an extra submarine that just happened to be passing through. (England, by the way, was not named for the well-known country, but for a gentleman by that name -- :D)

Forester
31-05-2011, 12:31
England, by the way, was not named for the well-known country, but for a gentleman by that name I wonder where his ancestors came from... ;)


I read in notes that Dad left me, that Forester had "Split Hedgehog" fitted. I'd never seen a photo of this set-up, but it seems from reading "British Destroyers from Earliest Days" that this installation was quite common. It allowed a ship to retain both the A and B guns for firing ahead when chasing E-boats and surfaced U-boats.

BTW, they're not on the ship post 1942 refit as shown in my signature photo. They were fitted in April 1943.

BobM
05-03-2012, 20:15
A book by Gerald Pawle entitled 'The Wheezers and Dodgers' gives some very interesting information about the development of this weapon.

The genesis of the project lay in the development of a spigot mortar by Major Jefferis as the basis of an anti-tank weapon, the 'Blacker Bombard' after the originator of a spigot Lt. Col Stuart Blacker. Blacker had approached the Admiralty before the war suggesting a spigot weapon might be used against submarines but was told there was "no naval requirement".

When war came Charles Goodeve who had been placed in charge of a team of original thinkers tasked with developing new weapons championed the idea. It was Goodeve's idea that instead of firing one bomb it should fire a series. Goodeve met some opposition. Apparently on approaching a senior member of the Ordnance Board he was told:
"This idea was put up by Major X in 1910, and it was turned down by the Ordnance Board then. The spigot mortar was put up by Colonel Blacker in 1930, and was turned down again. It was put up by Major Jefferis in 1939, and the Ordnance Board turned it down for the third time. If God Almighty Himself sponsored the spigot mortar, I tell you it would still be turned down by the Ordnance Board!"

The early projectiles were made by Boosey & Hawkes who are better known for making musical instruments. The name 'Hedgehog' was the winning entry in a competition to find a name with the winner receiving a bottle of sherry for his idea.

At the time work began the Hedgehog was up against several other ahead throwing weapons: the Bell-mouthed Bastard, the Fairlie mortar and a couple of others. The hedgehog eventually triumphed because the problem of the fuses was solved. How this was done is extremely interesting and will form the basis of my next post.

BobM
06-03-2012, 08:45
The principal challenge was posed by the Fairlie mortar and its supporters in the Admiralty. This weapon used a projectile with an iron nose which limited the quantity of explosive carried to 20 pounds with the fuse carried in the tail.

Goodeve and his team designed the hedgehog bomb with a load of 30 pounds of explosive fired by a fuse in the nose and used a tubular tail to confer stability. Experiments with a range of designs revealed that bombs with a flat nose were less likely to skid on hitting the surface of the sea. Further experiments showed that a 20 pound charge would not do enough damage to submarine plating. Goodeve was uncertain whether their 30 pound charge would be any better. One source of concern was that if the bombs hit the deck of submarine rather than the pressure hull the explosive force would be reduced. To find out how much effect this deck would have it was vital to know the height above the pressure hull of the deck. Up to date information about U boats was not immediately available but fortunately an Italian magazine ran an article on the Italian navy which included a picture of a man standing on the pressure hull to work on the deck of a German U boat. By calculating the approximate height of the worker's legs it was possible to estimate this distance.

Various types of fuses were tried to ascertain which was most effective with the best proving to be a mechanism activated by a propeller which began turning as the projectile hit the water.

The idea behind the pattern of charges was to catch a U boat in any combination of evasion manoeuvres it might attempt when it's commander knew it was under attack. This pattern was worked out using a device like a roulette wheel on which a scale model of a submarine was placed. Over many days tiny missiles were thrown at this model and the result was the discovery of the correct elevation of the spigots.

In the next post I will describe the trials and how the weapon was finally 'sold' to the Admiralty.

johnrey
28-05-2012, 09:54
On 20th September 1943 HMS Escapade was unlucky enough to be the only RN ship heavily damaged by its own Hedgehog unit. Escapade had stopped to assist the frigate Lagan which had just had its stern blown off by a homing torpedo. On locating the U-boat responsible and firing her Hedgehog the bridge crew of Escapade witnessed a massive explosion above the bows. One of the bombs had exploded permaturely when leaving its spigot. This practically blew off the bow of the ship and there were 16 dead plus nine injured. Amazingly she still managed to tow the battered Lagan back to Northern Ireland and Escapade was then repaired at Portsmouth later that month. Lagan and Escapade must have been a grim and bizarre sight as they pulled into port together!

Mark

My father Richard 'Snowy' Reynolds was a signalman and on the bridge at the time, he woke up with his nose split open and his Barr and Stroud binoculars that were around his neck now missing! He's passed on now but I was reminded of the story the other day when I came across this image on the IWM website, it shows what he would have seen... http://media.iwm.org.uk/iwm/mediaLib/30/media-30279/large.jpg?action=d&__utma=1.1541942361.1338198730.1338198730.13381987 30.1&__utmb=1.7.10.1338198730&__utmc=1&__utmx=-&__utmz=1.1338198730.1.1.utmcsr=google|utmccn=(orga nic)|utmcmd=organic|utmctr=hms%20escapade%20damage&__utmv=-&__utmk=27964092

Kind regards

John

Forester
30-05-2012, 12:35
In that image it looks like the 'A' Gun that has taken the hit and been blown off its mounting. One can imagine a projectile failing to leave the spigot properly and bouncing into the back of the gun.

nick60
08-06-2012, 15:15
I always thought the "Hedghog" was fitted before 1943?

When the V and W's were converted to long range Escort, "A" gun was removed and replaced with the Hedgehog. I understood this conversion programme took place in 1941-42.

Have I got this wrong?

jainso31
08-06-2012, 15:30
The Hedgehog (also known as an Anti-Submarine Projector) was an anti-submarine weapon developed by the Royal Navy during World War II, that was deployed on convoy escort warships such as destroyers to supplement the depth charge. The weapon worked by firing a number of small spigot mortar bombs from spiked fittings. Rather than working on a time or depth fuse like depth charges, the bombs exploded on contact and achieved a higher sinking rate against submarines than depth charges did.
The Hedgehog received its name because when unloaded, the rows of empty spigots resembled the spines of a hedgehog.
It was developed by the Directorate of Miscellaneous Weapons Development based on the British Army's Blacker Bombard and entered service in 1942.

jainso31

nick60
07-08-2012, 20:59
Thanks Jainso

Should have known you would have the definitive answer......

Forester
08-08-2012, 12:55
I'm very interested in the "Split Hedgehog" that was fitted in Forester in 1943just before she joined C1 Escort Group in Londonderry, but there seems to be no photos of this installation, although I'm aware of several ships being so equipped. There was one each side of the forecastle just behind "A" Gun - which remained in place. One of those who manned this weapon describes sheltering in the lobby at the forrard end of the superstructure, with reloads being passed up in boxes from shell room via the messdeck below. They had to bring the empty boxes back, so they were stacked on deck instead of throwing them over the side as "gash".

For Overlord, a 2 pounder was fitted on the bow for chasing "E" Boats, so what with that, the "A" Gun and the split hedgehog, it must have been very crowded up the pointy end during operations in the channel!

Mitch Hinde
08-08-2012, 14:07
Hi All

Is this a split hedgehog or just two mounted alongside each other?.

Mitch Hinde

Forester
08-08-2012, 14:28
That looks like two full hedgehogs mounted side-by-side. The crewman's helmet suggests they are in a U.S. Navy ship [or else one of His Majesty's ships with a U.S. visitor aboard]

This is what one source has to say on the subject. . .

Quote:
HMCS Assiniboine
on her way under tow she was wrecked off Prince Edward island on 10th November 1945,, HMCS ASSINIBOINE showing A gun and the fog lookout closed up as the eyes of the ship, .Date Laid Down Date Launched Date Commissioned
1 Oct 1930 29 Oct 1931 19 Oct 1939
Date Paid Off Date of Re-Commission Date of Disposal
8 Aug 1945 1 Nov 1945

Ship Remarks The ship's armament would be modified to two 4.7-inch guns (forward), one 3-inch AA gun (aft), four 21-inch torpedo tubes (1 x 4), six 20-mm machine guns and the split "Hedgehog" anti-submarine mortar. Usually, the normal Hedgehog mount would be placed on the "B" gun deck of this size of ship, and the 4.7-inch mount would be removed. However, the smaller split version of Hedgehog allowed two smaller mounts to be sited on either side of "A" Gun, thus allowing the ship to retain the second 4.7-inch gun forward.
Unquote.

It may be coincidence but Assiniboine was leader of C1 Escort Group at the time Forester joined from Home Fleet.

jainso31
08-08-2012, 14:47
Mousetrap (ASW Marks 20 and 22) was an anti-submarine rocket used mainly during the Second World War by the U.S. Navy and the U.S. Coast Guard. Its development was begun in 1941 as a replacement for Hedgehog, a British-made projector, which was the first ahead-throwing ASW weapon.
These, however, were spigot-launched, placing considerable strain on the launching vessel's deck, whereas Mousetrap was rocket-propelled. As a result, Mousetrap's four or eight rails for 7.2-inch (183 mm) rockets saved weight and were easier to install.
The rockets weighed 65 pounds (29 kg) each, with a 33-pound (15 kg) Torpex warhead and contact pistol, exactly like Hedgehog.

By the end of the war, over 100 Mousetrap Mark 22s were mounted in U.S. Navy ships, including three each on 12 destroyers, and submarine chasers (usually two sets of rails).

jainso31

Forester
08-08-2012, 14:56
This is the only image I've found showing a ship with split hedgehog installed. HMCS Assiniboine again.

120947

bobking
01-01-2013, 01:07
As I was born just after the conflict, I never saw a Hedgehog fit; In the initial installation, was the weapon first mounted on the foredeck, just ahead of the fo'cstle, and just behind where the A mount would have been, then moved up to the B gun position, where it seems that single Squid mounts were, replacing Hedgehog? Thereby avoiding the heaviest seas.

In the Black Swans, where were the Hedgehog mounts? Were they dual fit either side of the fo'cstle, or split. They would have to be up front somewhere, but on photos I haven't spotted the mounts. OR , were the weapons just fitted in the most suitable, available position.

Forgive my ignorance of most Naval subjects, I was a simple Air Traffic Controller! Bob King

ivorthediver
01-01-2013, 15:31
After noon Bob , Welcome to the Forum ,

I'm sure some one will answer you soon about your query , I seem to recall seeing a picture of an accidental firing of a Hedgehog which I was looking for when I came across your post , and I recall it made a right mess of the area just forward of the bridge requiring substantial repair work

Old Salt
01-01-2013, 21:00
During our workup at Pearl Harbour we often shared exercises with an old DE still fitted with Hedgehog.

A young ensign was showing young ladies around the ship. He showed them the Hedgehog and got to the part ..... " to fire you push this button here.."....... Fortunately only dummy projectiles : the ones that fell into the harbour caused no problems. The ones that landed in the officers' carpark certainly did !

Brian

Scurs
01-01-2013, 21:22
bobking.................In SURPRISE (1962), the Hedgehog was in 'A' Gun position.

Old Salt............Happened in KEPPEL with Mortar Mk.10 too.............a salvo of "lights" sailed sternwards, cleared the breakwater at Portland, and neatly splashed down alongside Capt.F2 who was astern of us (either TEAZER or WHIRLWIND, can't remember which).

bobking
01-01-2013, 23:13
Thank you, Scurs.

I was flabberghasted to see in a photo of HMS Surprise, (navyphotos.co.uk) to see the Hedgehog mount in the A gun position, where it must have been installed in 1943,--empty by the look of things; had it been fired recently??

On the quarterdeck appear to be no less than 3 Whirlwind Helos!!

Also, Surprise must have been about the biggest Admiral's Barge EVER. She must have been a bit of a mongrel.
Bob King

PhilMeds
02-01-2013, 09:51
The Hedgehog can just be see on the forecastle between the two large ventilation mushrooms.

Philip.

bobking
02-01-2013, 12:37
Many thanks for that Phil, nice picture, if a little grainy. Any idea where the Hedgehog was on Black Swan, or modified Black Swan?
Bob King

Scurs
02-01-2013, 15:14
bobking..........When I joined in 1957, we were taken around the TAS School at GANGES. where we were shown a Hedgehog and told, "These are obsolete and you won't find one on a ship in the Fleet now"..................WRONG!.......fast forward to 1962-63 !!! :D:D

Yes in one exercise. we acted as a sort of Helicopter Carrier............Quarterdeck PO was not impressed worried about what those things might do to "Holy of Holy's" quarterdeck. The Hedgehog, got fired once, and only once, during the 14 months I was in the ship. Nobody was actually brave (or foolish) enough to fire the 4" even once though !
The Hedgehog firing, was not, shall we say, an all together successful venture............I think, maybe 6/24 bombs actually went where they were meant to go - the remainder - some didn't go anywhere and stayed on the mounting, some went a few feet up in the air and came down on the foc'sle, coming to rest by the breakwater.....some bounced off various parts of the ship and plopped overboard...........the submarine crew probably did themselves a mischief, through laughing so hard!
The next time we were involved in exercises it was back to our usual role of acting as Convoy Merchant ship.

You see........back in 1944, she was designed for 19 knots top whack, with the weight of all that extra accommodation and large wooden quarterdeck aft, by 1962, it would be pushing it to manage 14 knots - in fact above 12 knots the Engineer used to phone the bridge and asked for the ship to slow down as the main bearings were overheating! Then much below 9 knots, with all that extra weight, she would virtually lose steerage-way, or at the best be very reluctant to answer the helm. It was "interesting" being Quartermaster on that ship (as I was for most of my time in her).

ivorthediver
02-01-2013, 15:57
Ok lads after looking everywhere I found it in some old research copies from when I built a model boat for my grandson a few years back .

If my memory can be relied upon:rolleyes: it was HMS Escapade but don't rely on that as I say it was a print off a friend who was telling me a little about the weapon whilst I was building a Flower class model and said that "Teething" problems were overcome [ bit of an understatement ] and in this incidence it virtually destroyed the Bridge of the vessel

PhilMeds
02-01-2013, 17:54
With reference to the Hedgehog being "Touchy" if anyone not familiar with her erratic ways, decided she should be fired.

During the whole commission, including the Portland Workup, H.M.S.Veryan Bay only fired her once

This was during her twelve months deployment to the West Indies & the Antarctic.

After a visit to the beautiful island of Grenada, located in the southern Caribbean Windward island chain, it was decided that the Hedgehog would be “Tested”.

We were just leaving after the visit and were well out to sea and by a strange coincidence in the middle of their fishing area, when the misguided action took place.

Everything went according to plan; the Hedgehog threw all her children out of the pram as requested. The ship sailed towards the disturbed water but nothing was heard until the ship had sailed through the point of impact. The babies all cried together as they saw us pass over head.

After the initial shock of feeling the ship lift and shake, the captain ordered stop and check for damage. The inspection revealed that a line of rivets on theStarboard were leaking oil. The repair was carried out along side in Trinidad. This involved transferring the oil to another tank and then the Shipwrights mate had to replace the rivets with bolts. The ship for the next eight months sailed with the evidence of the repair. I am not certain of the number but we always went alongside Port-side-to.

I should add that not one fish came to the surface but the Captain did receive some unkind words from more than upset senior officer ashore.

Philip.

Scurs
02-01-2013, 20:27
Phillip............bit puzzled really..........not being a TAS rating, I may have this wrong, but:-

I was always under the impression that the Hedgehog "Bombs" were "contact" thingmebobs that only went "BANG" if they actually HIT something. In other words they had to actually hit the submarine to explode............or..........could they be pre-set like depth charges? When we did the firing they were "lights" (no explosive warhead), which given the "performance" was just as well. :confused:

bobking
03-01-2013, 00:07
Although maybe slightly off topic, when I was down at Portsmouth for the 50th Anniversary celebrations, I met an old codger who it turns out was on one of the first LC(A)'s which went in on the first wave. He said his boat had Hedgerow, plus one full reload. They had just fired the weapon, and were in the process of re-loading, when they were blown out of the water by a German shell. He was quickly picked out of the water by another LC(A), and that commenced it's run in , and that hit an obstacle. so he ended up in the water again. He was picked up agsin, this time seriously injured, and taken to a Destroyer, which took him back tp Haslar. His war lasted about half an hour. How incredibly brave was that!! He was onl;y introduced as Ron.
Bob King

bobking
03-01-2013, 00:09
Although maybe slightly off topic, when I was down at Portsmouth for the 50th Anniversary celebrations, I met an old codger who it turns out was on one of the first LC(A)'s which went in on the first wave. He said his boat had Hedgerow, plus one full reload. They had just fired the weapon, and were in the process of re-loading, when they were blown out of the water by a German shell. He was quickly picked out of the water by another LC(A), and that commenced it's run in , and that hit an obstacle. so he ended up in the water again. He was picked up agsin, this time seriously injured, and taken to a Destroyer, which took him back tp Haslar. His war lasted about half an hour. How incredibly brave was that!! He was only introduced as Ron.
Bob King

bobking
03-01-2013, 00:09
sorry double post!!

PhilMeds
03-01-2013, 01:53
The plan was that the bombs would explode when they reached the bottom, i.e., after we had pass well beyond the “Splash” point and then we would stop to fish. No one was more surprised than those on the bridge when the ship was shaken by the shockwave.

Philip

Scurs
03-01-2013, 22:19
Ahh I see Phil..........thank you, makes sense now! Btw, both the Squid and Mortar Mk.10 were efficient when fish was needed on the menu! :D

ap1
03-01-2013, 23:23
Here’s a bit of detail on the Hedgehog, from a paper called "Anti-submarine Weapons";
which I’m about to post in full elsewhere, very shortly.

© Crown Copyright/MoD (1956).

HEDGEHOG.

By

COMMANDER D.H. RUSSELL, R.N.


Before the comparatively advanced development of ahead throwing weapons,
the only method available for determining the depth of the target was from the
range at which asdic contact was lost, coupled with a knowledge of the shape of
the lower edge of the asdic beam. It was this and the limitations of the depth
charge pistol depth adjustment, which were the principle deficiencies of the
early equipment and decided the course of development.

The idea of throwing a charge ahead of the ship to a position where asdic
contact was still maintained, was born just before the outbreak of the last war.
Development began in 1940 on about six projects of this type. In view of the
high order of deck thrust caused by the discharging gear, the trend was to
discharge a number of small charges, at short time intervals, to form a calculated
pattern on entering the water. As development proceeded, a weapon known by
the code name ' Hedgehog ' emerged as the most promising for fleet use, and
the remaining projects were ultimately dropped.

The Weapon System

The development of Hedgehog and its associated equipment was divided
between the Ministry of Defence and the Admiralty, the projectile being
designed at the Admiralty Mining Establishment. The prototype weapon,
built under contract by Messrs. Foster Wheeler and based on a design drawn
up at the Anti-Submarine Experimental Establishment, underwent sea trials in
1941. It must be borne in mind that this weapon was developed during the
most critical period of the war and consequently it was of supreme importance
to get it to sea with the least possible delay. For this reason its design was kept
as simple as possible.

The mounting consists of four beams each carrying six spigots mounted on
fore and aft trunnions so that they can be rocked by hand control from a
position behind the blast shield. The projectiles are fired electrically over
a 2-second period by a ripple firing switch so that they enter the water together
in an approximately circular pattern 120 feet in diameter at a range of about
210 yards.
The original design was intended to replace the forward gunmounting
in escort vessels. In some cases it was particularly desirable to
retain this gun, and for this reason the mounting was re-designed in two sections,
each containing one pair of beams. One section was mounted each side of the
ship, the starboard half being the controlling mounting and the port half a
slave.
The two half-mountings were connected by a telemotor link and were
slightly set in to allow for their off-set from the ship's centre line. This version
was known as the ' Split Hedgehog '. On the after end of the mounting behind
the blast shield an operator manned the hand drive to the tilting beams, and
matched a pointer linked to the beam drive with a gyro stabilizer pointer
indicating the vertical datum. Given practice and fair weather, a reasonable
degree of correction for roll was obtained. As the mounting is designed to fire
ahead, however, it was necessary to arrange to compensate for small course
errors during the attack. This is done by controlling the vertical datum used
for roll correction from the Captain's Bearing Indicator on the bridge. This is
only possible for course errors up to 20" as any aim-off done in this manner
distorts the pattern entering the water and reduces its lethal area.
Two types of fire control system were developed at the same time as the
weapon, to provide vertical indication for the operator controlling the
mounting.

Fig5127005

The Type 'A' fire control gear was specially designed and employed a self-erecting
gyro, controlled by mercury-switch operated torque motors, to provide
the vertical datum. The gyro casing was mounted at the after end of the
mounting. Although this practice is now well established, at that time the use
of mercury switches to control gyros was considered rather novel, and as a
second string, the type ' B ' fire control gear was also developed. This was
sited below decks near the centre of roll and used a standard Evershed and
Vignoles fire control gyro with a powered follow-up drive working an 'M' type
transmitter. The receiver was fitted at the operator's position on the mounting.
The gyro-wander was hand corrected through a differential using spirit levels
as a datum.

The later versions of Hedgehog have the omissions, which were originally
accepted in the cause of simplicity, rectified, and metadyne remote power
control is fitted in conjunction with a Type 'C' roll unit fitted below decks to
provide automatic roll correction. The firing operation has also been made
automatic by fitting a motor-driven ripple-firing switch operated from the
range recorder firing contacts.

The projectile, developed at the Admiralty Mining Establishment, weighs
65 lb and contains 34 lb of explosive. Initiation of the charge is by means of
a contact fuse, armed by the firing impulse, and also by its passage through the
water.
The tail fitted to stabilize its flight through air incorporates slightly
'set' radial fins to impart the rotational movement to centre the projectile
while sinking. The tail tube, which fits over the mounting spigot, carries the
cartridge containing the propellant. It is built in at the upper end with the
primer making contact with the firing pin, housed in the top end of the spigot.
The sinking rate of the projectile is about 29 ft per second. Once it is armed
and it strikes a hard surface an inertia weight is dislodged which releases a
spring loaded firing pin.

Method of Attack

The detection facilities available in the early Hedgehog fitted ships, were
much the same as those already described when discussing depth charges.
During the critical period, when Hedgehog was developed, it merely provided
an additional armament for ships fitted for depth charge attack, consequently
certain advantages of the ahead-thrown attack were not fully exploited in the
early days.
The addition of a bearing recorder, already mentioned, was the
most significant contribution to achieving a controlled attack. There was no
depth finding asdic, only a 'Q' attachment which considerably shortened the
contact range without giving any positive information as to the target depth.

In the absence of depth information, it was necessary to choose an optimum
target depth of about 175 feet to enable a suitable allowance for blind time
during the sinking period of the projectile to be made for the purpose of setting
the range recorder. However, for deep targets, where blind time was large, the
inaccuracies were too great and depth information became essential.

As the weapon is essentially designed to fire ahead, the attack procedure is
to steer a centre bearing course deduced from the bearing recorder, and then,
after making the appropriate settings to the range and bearing recorders to
steer the deflection angle ahead of the target. Small errors in this angle are
compensated by feeding continuous bearing information from the Captain's
Bearing Indicator into the roll correction instrument as already described.
Thus, when the range recorder firing contacts make, the position where the
projectile pattern enters the water is properly computed with certain depth
limitations.

The use of contact fuses can give rise to much debate. Their successful use
denotes a certain hit, and the destruction of the submarine. Their unsuccessful
use does not disturb the asdic conditions for a further attack. The overriding
disadvantage, however, is the loss of the cumulative effect, materially and
morally, of a number of near misses. Compared with a depth charge attack,
where the effective radius of a pattern is about 260 feet, the Hedgehog had to
be regarded as a precision weapon since, with contact fuses, the lethal radius
became the radius of the projectile pattern, that is, about 60 feet.

It can be appreciated how the inaccuracies due to the sinking time of the
projectiles mount up without accurate depth measurement of the target, and
how much depends on the skill of the operators of the early roll correction
arrangements. However, in the relatively confined waters of the English
Channel at the end of the war, results from worked up ships showed a probability
of success of 30 per cent. A significant improvement over the depth
charge attack.

bobking
04-01-2013, 01:23
Thanks, Andy. That is superb detail!!Bob King

ap1
04-01-2013, 15:02
Thanks, Andy. That is superb detail!!Bob King

Thanks, Bob. Good to know the effort is appreciated.

The full paper is now posted on its own thread 'Anti-Submarine Weapons: Engineering' in 'Other Naval Topics' too.