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Depth Charges.

Discussion in 'Ships & Shipborne Weaponry' started by Liberator, Oct 8, 2007.

  1. Liberator

    Liberator Ace

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    These weapons, which had been used by the Royal Navy since 1918, had a total weight of 450 pounds, contained the explosive Amatol (with a charge/weight of 75%) and were detonated by a hydrostatically fused pistol. In the early days the minimum depth of detonation was 50 feet. The Mark VII depth-charge was a adaptation fitted with a nose cone and tail unit to provide some ballistic performance when being dropped from an aircraft. Initially these D/Cs were dropped in sticks with intervals of 36 or 60 feet between charges. These weapons, restricted to a maximum release height of 115 feet entered RAF anti-submarine service in 1940.

    In April 1941 the Mark VIII D/C came into service with a filling of Torpex - 30% more effective than Amatol. Nominally of 250 pounds weight the Mark VIII weighed in at 304 pounds with nose and tail fittings and had a lethal radius of 28 feet against submarines. A small interval between charges resulted in a short stick length which increased the risk of the whole stick under-or overshooting and , on the recommendation of RAF Coastal Commands Operational Research Section, the interval was increased to 100 feet at the end of 1942. At about this time an improved pistol capable of initiating the explosion at a reduced depth of 25 feet came into service, making these weapons more effective against submerging submarines. The depth-charge became the standard weapon of the Allies in the battle against enemy submarines.
     
  2. Hawkeye90

    Hawkeye90 Member

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    Very interesting. Ironic as well, being that I watched Das Boot last night. Depth charges really were a nightmare to the wolf pack.
     
  3. lwd

    lwd Ace

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    By the end of the war hedgehog was becoming very widely used if not quite as wide as depth charges and was proving far more lethal.
     
  4. Onthefield

    Onthefield Member

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    Another movie that really shows you the damages of depth charges is U-571. Hell on earth, that's it!
     
  5. Joe

    Joe Ace

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    Having watched a Sumbarine movie (don't ask what, I only saw the end of it. It was definatly in the Pacific though), was there really a click before the charge went off?
     
  6. T. A. Gardner

    T. A. Gardner Genuine Chief

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    There are quite a few more different depth charges used during WW II than that:

    The US used the Mk 3, 4, 7 and, 9 while the British had the Mk III, VII, VII (airborne), VII, X, X*, X**, and XI (airborne). In addition the US used Mousetrap and Hedgehog while the British used Hedgehog and Squid in ahead thrown weapons.

    The typical arrangement of depth charges for a pattern were 10 and 14 charge patterns. Which was used depended on the situation and the ship's capacity to throw and drop depth charges. For most ASW oriented ships the 10 or 14 pattern was standard. The 10 required two K guns per side along with two stern racks. The stern racks would drop 3 charges each while the guns would fire four additional charges outside the stern drop. The 14 pattern used 3 K guns and the stern racks increasing the pattern size to 4 from each stern rack with 6 from the K guns.

    Unique among the above depth charges was the British Mk X. This was a monster depth charge fired from a torpedo tube. The Mk X was the most massive depth charge used in World War 2. Only the British used this model. The Mk X had a 2000-pound explosive filler, making it generally referred to as the “one-ton” depth charge. Its all up weight was 3050 pounds. Unlike other depth charges, the Mk X was fired from a standard 21” torpedo tube. Normal practice for the Royal Navy was to replace one torpedo with a Mk X per destroyer engaged primarily in ASW operations. Their fleet destroyers normally did not have one of these weapons issued. Depth settings for the fuze of the Mk X* were 200, 600 and, 800 feet. The Mk X** was increased to 1500 feet maximum.
    Sink rates were: Mk X 6 fps, Mk X* 21 fps and, Mk X** 50 fps.
    It was sort of a pre-nuclear nuclear depth charge.

    (italics from a rather lengthy paper I wrote on WW 2 ASW weapons)

    Some other oddities: The Japanese never went with a K gun on their destroyers. Instead, they stuck with the older Y gun (fires a depth charge to both sides simultaneously). Their normal ASW outfit was two Y guns and two racks.

    The US K gun used a black powder charge and fired the arbor (the thing the depth charge was mounted on) along with the depth charge. The British opted for a hydraulic / pneumatic system where the arbor was not fired with the depth charge. This was chosen to save steel, not because it was more efficent. The British K gun could fire to about half the maximum range of the US model.

    And no, there is no "click" before the charge goes off.
     
  7. skunk works

    skunk works Ace

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    I heard the charge was a 5" cartridge (sawed off I expect), and as you say "black powder" ? I've also heard this was the same system used to launch early torpedo's from PT's (like the 109)(that little lump atop the end of the launcher). I've also heard that the charge would light up the night sky and the Japanese could see this and would open fire at the flashes.

    True or False ?
     
  8. T. A. Gardner

    T. A. Gardner Genuine Chief

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    This is sourced to orginal US Navy ordinance manuals (since declassified):

    The standard projector for firing depth charges to the side of a ship was the K gun or, Projector Mk 6 (U.S.). This projector was a type of spigot mortar. In use, the projector was loaded with 1 to 3 sphereohexagonal black powder charges (depending on the range desired) and a cradle assembly loaded onto it. The depth charge was then chained to the cradle and held there by a release link that opened upon firing.
    Firing distances varied with the charge(s) loaded and the type of depth charge used. For the Mk 6 depth charge the ranges were 50, 75 and 120 yards for charges 1 to 3 respectively. The Mk 9 teardrop could be fired to 60, 90 and, 150 yards using similar charges.

    The charges are contained in a 3" diameter x 13" long case. These are also the same charge used to launch torpedoes from the Mk 14 etc. above water torpedo tube.

    I would think that yes, there probably would have been a good sized flash associated with it going off along with a large puff of smoke.
     
  9. Joe

    Joe Ace

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  10. Repulse

    Repulse Member

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    i usually call them death charges because they do cause death.:D
     
  11. fer-de-lance

    fer-de-lance Member

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    The most effective shipboard ASW weapon in WWII was the Royal Navy's SQUID ahead throwing mortar. This was a 3-barrel mortar that threw three heavy (394lb; 207lb of minol), fast sinking (44 fps) charge ~270 yards ahead of the ship. The SQUID charge or "bombs" were not depth charges per se as they were time fused. The Royal Navy had a depth finding "Q" attachment (fan beam that scanned in elevation) for the Type 147 Asdic (147Q) which provided the target depth displayed on a chemical chart recorder. With this information, and a reliable sink rate, the time fuse on the SQUID bombs could be set to explode at the target's depth. The three barrels would fire three charges in a triangular pattern with 120ft sides to bracket the target.

    Wartime "Castle" class frigates were equipped with SQUID and the "Loch" class frigates had Twin SQUID, two sets of three. Twin SQUID fired all six charges with three charges set 60ft below the other to try and bracket the target within the two triangles (ie. cover for any errors in depth finding or target maneuvres).

    SQUID had a very high kill probability on WWII Type VII and Type IX U-boats. It was also considered the only effective weapon against the Type XXI fast submarine. It replaced hedgehog as well as conventional depth charges in the Royal Navy after WWII.

    The US Navy also received depth finding sonars for some of their destroyer escorts (DE). Some DE also received a magnetic fuse depth charge, the Mk 8, for use in the Atlantic. The Mk 8 was not streamlined and had a relatively slow sink rate 8-12 fps but the magnetic fuse gave it a great advantage, potentially exploding the charge when it gets close to the target. On May 13, 1944, USS Francis M Robinson used Mk 8 with magnetic settings in the sinking of RO-501, a U-boat transferred to the Imperial Japanese Navy. After scoring two hits with hedgehog, Mk 8 were launched with magnetic settings. Two charges exploded 24 and 38 seconds after the first were fired from K-guns. The depth recorder followed the RO-501 as she sank and exploded.

    USS Chatelain also scored with magnetic fused Mk 8 when she damaged the U-505 june 4, 1944, forcing her to surface which resulted in her capture by a boarding party. After gaining sonar contact with the U-505, the Chatelain attacked with hedgehog but scored no hits. She then charged in for a depth charge run. With a QCS sonar whose beam was fixed in elevation, the Chatelain could not determine the depth of her target. However, the depth of the target could be estimated by the time when the sonar contact is lost as the target passes under the coverage of the fixed sonar beam. Contact on the U-505 was lost at approximately 50 yards, suggesting a shallow depth.

    The Chatelain launched a full pattern of Mk 8 with magnetic setting and hydrostatic back-up. One of the charges exploded much earlier than the rest, suggesting that the magnetic fuse may have been actuated when it passed close to the target.

    Shortly after the depth charge pattern exploded, the U-505 was forced to surface and was subsequently boarded and captured.
     
  12. lwd

    lwd Ace

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    I believe hedgehogs figured prominatly in USS Englands sting of kills. From:
    USA ASW Weapons

    British ASW Weapons
    mentions that the Britts didn't have as much success with hedgehog as the US did. It's not clear from these sources that Squid was supperior to hedgehog. After wars end the US started going to ASW torpedos as did the Britts I believe.
     
  13. Albrecht von Hesse

    Albrecht von Hesse recruit

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    I've been trying to research the Mark X and have been coming up dry. Basically I'm looking for the following information:

    1. its physical shape, appearance and dimensions,
    2. sink rate (seems to be 6 fps, not mps, yes?),
    3. 'kill' radius (compared to Mark VII heavy),
    4. damage comparision/ratio compared to the mark VII heavy,
    5. ship classes that carried them,
    6. date of service entry,
    7. quantity normally carried (my research seems to indicate no more than two were carried).
    Was the Mark X's depth variable-set? By that could it be set for discreet depths as were the Mark VII and other depth charges? Or did it have fixed depth settings?

    Thanks!

    ~Albrecht
     
  14. Skipper

    Skipper Kommodore

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    Hi Albrecht. I noticed you are a new recruit. I you wish to do so you can introduce yourself in the new member section. This way many more will notice your request and look at your posts. We have probably quite a few members who know about the Mark X, no promise here.
     
  15. Jan7

    Jan7 Member

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    Hi Albrecht, welcome at the WW2F!
    You may find more of naval weapons in these pages: NavWeaps - Naval Weapons, Naval Technology and Naval Reunions - Navy Weapons . I ts a big site and helped with a powered and integrated search machine.

    Your introduction in the New Forum members its a good option. Don't hesitate of use this metod. Its a lot of new friends can help you......


    Jan.
     
  16. GarethJohn

    GarethJohn Member

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    Hi Guys

    Ive been searching for someone who can assist me concerning Depth charge patterns during 1942.

    The ship in question is HMS Active H14, I understand she was fitted with Y guns, however photos I have of the period show what appear to be K guns. She sank a U-boat during October 1942 using a ten pattern depth charge attack.
    My question is, if she had Y guns would this pattern still be possible and where would these Y guns be mounted?

    Thanks in advance!
     
  17. Carronade

    Carronade Ace Patron  

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    Everything I've seen on the RN has them using K-guns, and the ten-charge pattern would require two K guns per side as described earlier in this thread.

    The Y-gun may have been unique to the USN. Since it fired simultaneously to both sides, it was mounted on the centerline, which was its big disadvantage since c/l postions were also needed for guns, torpedos, not to mention much of the c/l was taken up by superstructure, funnels, etc. Ships with Y-guns usually only had one of them.

    One thing that might be a bit misleading, the RN designated its ships' main guns/turrets by letter; on a four-gun ship like Active as originally built the 4.7" would be A, B, X, and Y guns. Y gun was on the fantail; ironically in antisubmarine conversion it was often removed to accommodate more depth charges.
     
  18. GarethJohn

    GarethJohn Member

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    Now I see why 'Ace' is listed under your name :D

    Thank you so much!

    Kind Regards
     
  19. Carronade

    Carronade Ace Patron  

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    I dug out Allied Escort Ships of WWII (Peter Elliott) which has sections on RN and USN weapons and discusses the Y gun only in the latter, another indication that it was probably not on British ships. K gun strictly speaking is also an American term, but the weapon was similar to the British depth charge thrower. Depth charge throwers are always described as being mounted in pairs, 2, 4, or 8 per ship, i.e. K gun style.

    Many of the older British destroyers were converted to escorts, starting with WWI-era ships like the V&W class, also most of the surviving A-I classes. This included removal of Y 4" or 4.7" gun and one or both sets of torpedo tubes in order to carry more depth charges. "A" gun on the forecastle also often went; when the Hedgehog was developed it was sometimes mounted there. The Director Control Tower was often replaced by a Type 271 radar 'lantern'; although it sounds a bit odd to us today, radar was an important antisubmarine tool in WWII since U-boats operated and attacked on the surface whenever possible. This meant that the remaining guns had to operate in local control, aimed optically/manually by the crew on the mount, but that was considered adequate for engaging surfaced U-boats.

    As I understand it, "Ace" denotes the volume of posts rather than their cogency, but thanks!
     
  20. GarethJohn

    GarethJohn Member

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    Thank you for the info, it makes a lot more sense now! ;) One of the Destroyers in question, HMS Active a prewar A class destroyer operated very succesfully in the South Atlantic and South African waters, She is credited with 3 U-boats sunk and fiited out exactly as you described. One of the few prewar destroyers to survive the whole war finally she was broken up in 1947.

    Thanks again!
     

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