Talk:Hedgehog (weapon)

Hedgehog in service

Was not the hedgehog placed in service late in 1941 and early 1942 (as opposed to 1943), the first one being on the HMS Westcott? Two references would be Clay Blair's Hitler's U-Boat War and Sir Charles Goodeve's short biography. Jayman435 (talk) 23:20, 22 September 2008 (UTC)

Fixed. TREKphiler ^{hit me ♠} 13:09, 23 November 2008 (UTC)

Suggest use of a info box like the one inserted to the right (Not all info in the box is checked)--Thorseth (talk) 09:22, 20 February 2009 (UTC)

Hedgehog
Hedgehog anti-submarine weapon, British WWII
Type	Anti-submarine Mortar
Place of origin	United Kingdom
Service history
In service	1942–1943?
Used by	Royal Navy
Production history
Designer	Directorate of Miscellaneous Weapons Development
Designed	1942
Specifications
Shell	65 lb (29 kg)
Calibre	7 in
Barrels	24
Effective firing range	200 to 259 m
Filling	30 lb TNT or 35 lb (16 kg) Torpex
Detonation mechanism	Contact

Language Use in Pic

I noticed on the English page for the Hedgehog that the description was in Spanish first, and then in English. After verifying that the pic was properly described on the Spanish page already (http://es.wikipedia.org/wiki/Erizo_%28arma%29), I removed the foreign language from the English page, where it should not have been in the first place. Deejaye6 (talk) 02:55, 2 November 2010 (UTC)

I restored the Spanish description and flipped the descriptions so that it's English and then Spanish as this is a British weapon. The description you edited is stored on Wikipedia Commons which is used to store media across all languages. At the bottom of the left margin for the Hedgehog (weapon) article is a list of languages. Those are Wikipedia's that have articles on the Hedgehog and any/all of them can use the same images from Commons. Ideally the description would have translations for all of the language specific articles that use the image. For example, I just added a Japanese description to Image:Hedgehog anti-submarine mortar.jpg meaning if you go to the Japanese language article for the Hedgehog at ja:ヘッジホッグ (兵器) and then click on the image (it's part way down the page), you will see an image page that's mostly in Japanese and has English, Spanish, and Japanese descriptions. --Marc Kupper|talk 18:15, 2 November 2010 (UTC)

Copyright infringement RESOLVED

Hi,

Following review of a recent change, I discovered that there appears to be some content which seemed to be copied from a website (see [1]). While the article is now not too heavily copied from the website, some changes to the articles such that the use of copyright materials be minimised might be appropriate.

— Andrew Y _talk 10:51, 29 May 2015 (UTC)

You're wrong. Plain and simple, why?

https://tools.wmflabs.org/copyvios/?lang=en&project=wikipedia&title=Hedgehog+%28weapon%29&oldid=664544673&action=search&use_engine=1&use_links=1

Did you even bother to check your own source? Nah I didn't think so.

Oh look!

http://modelshipwrights.kitmaker.net/modules.php?op=modload&name=SquawkBox&file=index&req=viewtopic&topic_id=217077&ord=&page=6

95% copy vio supposedly.

But a quick check of when the pages were posted: yes Aug 2014.

Here is the article as of August 1.

The poster obviously copied this article. — Preceding unsigned comment added by 81.132.173.149 (talk) 00:48, 30 May 2015 (UTC)

I will explain my reasoning here. The edits concerned made by 81.132.175.44 and 81.132.173.231 were made yesterday. In deciding it was copyright infringement (which I now agreed it wasn't), I made use of the two Copyvio reports here: [2] reporting the status after the two edits (rev 664544673) and [3] reporting the status before the two edits (rev 635127980). As you can see, the percentage confidence changed from 65.1% to 95.0% after the two edits.

Considering the edits were made yesterday, and as you correctly identified the pages were posted in Aug 2014, one would reasonably believe that the issue occurred in the two edits and they contains materials copied from the website. Except it was not the case. For some reason, [4] did not show up in the check for rev 635127980. I don't know why, but it is just the case. I checked the diff summary ([5]) and compared the highlighted region with the report (which was a wrong thing to do). I confirmed my suspicion and reverted the edit. I was wrong, I must say, but I did check my source. I just didn't use the diff summary correctly and for that I sincerely apologise.

I will respond to your message at my talk page there.— Andrew Y _talk 08:59, 30 May 2015 (UTC)

Is U-boat the preferred British English term for all submarines?

A question for User:BilCat in keeping with the user's preference for discussion of edits to be conducted on the appropriate article talk page: Unless U-boat is the preferred British English term for submersible warships I suggest the term submarine is preferable in this context because the weapon was also used attacking Japanese submarines. Can you provide a British English reference supporting a preference for U-boat? Thewellman (talk) 06:55, 10 July 2016 (UTC)

Actually, I was just referring to the IP user's change of "Second World War" to "World War II". I have no preference for either U-boat or Submarine, but since the IP user gave no reason for making the change, I just made a straight revert. - BilCat (talk) 07:21, 10 July 2016 (UTC)

Looks like the infobox could be updated to include users other than the royal Canadian navy, and used from 1942-present? Destructomat (talk) 03:00, 11 December 2016 (UTC)

Other users added and clarified. Tofof (talk) 04:23, 21 December 2016 (UTC)

In English language usage I've only ever seen U-Boat to refer to German submarines, presumably because they were prefixed with U-. Rcbutcher (talk) 04:58, 21 December 2016 (UTC)

In contemporary wartime British usage 'U-boat' referred to any enemy submarine, e.g., German, Italian, or Japanese. — Preceding unsigned comment added by 95.150.11.196 (talk) 12:02, 16 April 2017 (UTC)

Source? - BilCat (talk) 12:10, 16 April 2017 (UTC)

Churchill said so. It was to prevent confusion. Allied vessels were 'submarines', enemy ones 'U-boats'. — Preceding unsigned comment added by 95.150.11.196 (talk) 12:42, 16 April 2017 (UTC)

And the source for that? - BilCat (talk) 18:04, 16 April 2017 (UTC)

"Explodes When" - Inconsistency

Parts of the article claim that a Hedgehog bomb "only explodes on contact" and that a miss of a submarine means there is no explosion. This idea is further offered as a reason that Hedgehog was superior to depth charges: it didn't 'foul' the acoustics of the water and render sonar/asdic inoperable in the same way. None of this has citations.

Unfortunately, other parts of the article, namely the caption for this image, claim that the bombs explode regardless upon hitting the ocean floor. Though the caption's claim is not apparent within the image's associated description, it is in fact explicitly made by the image's source, p. 4: "Moberly's hedgehog charges explode as they hit the ocean's floor" (emphasis mine).

I've flagged this inconsistency, but it needs clearing up.

Tofof (talk) 04:21, 21 December 2016 (UTC)

I don't know this, it is just intelligent speculation, but I think that bombs exploding on the bottom in practise did not matter.

The Atlantic has an average depth of 3,646 m and the Type VII U-boat had a crush depth of 250–295 m. So the Hedgehog bombs that missed the target and exploded on the bottom would have a long way to fall before that happened. By the time they did explode the action might well have moved away and the considerable distance would attenuate the sound.

Also, the article does not actually say that Hedgehog bombs that missed the target will not explode, merely that ones which miss the target will not foul up the sonar 'picture' and I think that this is probably true.

FerdinandFrog (talk) 19:53, 21 December 2016 (UTC)

The article most certainly does claim that Hedgehog bombs that missed the target will not explode:

“ In addition, any explosion indicates a "hit" ”

So we're now talking about 48 bombs at 35 pounds of torpex in each for the standard dual-hedgehog attack. That's 1680 lbs of explosives, that do explode, regardless of whether or not they miss. That's equivalent to 5-6 UK depth charges (the Mark VII, typical in 1939-1942) at 290 lbs of torpex each, or 8-9 US depth charges (the late-war Mark 9, 1943-1945) of 200 lbs torpex each. And the standard depth charge attack was a pass with K-guns and stern racks to drop a pattern of 6-10 charges. So, we're talking about very similar amounts of explosive used in either case.

The explosion (and remember, elsewhere in this article, it claims "the subsequent explosion would trigger all the other bombs to explode as well") creates a gas bubble for an instant, which then implodes from the water pressure, then the momentum of the water actually ends up creating another (smaller) bubble, another implosion, and so on in cycles. The expansions and contractions create shock waves which a) damage the submarine if it's close enough and b) create a mess of loud reverberations and bubbles that get described as "disturbance" that fouls ASDIC/SONAR.

Why would 1600 lbs of exploding torpex from hedgehogs somehow not create "disturbance" but the same 1600 lbs of exploding torpex from depth charges would? So, the claim in #1 of operational usage clearly depends upon the hedgehog bombs not exploding unless on hitting a submarine.

Unfortunately, quantitative information about the phenomenon is hard to find; this article currently claims 15 minutes which I'm honestly certain is a gross exaggeration.

Finally, I disagree with the suggestion that the average ocean depth during an escort-submarine engagement was 3600m. The entire North Sea (save perhaps along the Norwegian Coast) is less than 150m deep at all points. And the relatively-northern main convoy route (see the HX/SC/ON 'lane' in [6] or the paths in [7] for example) traversed, substantially, the Reykjanes Ridge and the Rockall Rise - areas ranging from 300m to 1500m deep.

Tofof (talk) 04:54, 22 December 2016 (UTC)

I agree the current article has some confusing wording. I shall attempt to clarify the language when I find appropriate references; but I will offer a bit of explanation here. Detonation was initiated by striking a hard surface, but landing on a soft mud bottom would be unlikely to initiate fuze function. Detonation of a single hedgehog would not reliably cause sympathetic detonation of all other hedgehogs in the pattern. It should be remembered that until late in the war, most submarine operations including the major convoy battles were in deep ocean waters to avoid detection by coastal boat and aircraft patrols. Under deep water conditions a detonation from submarine depth would be significantly earlier and closer than detonations caused by striking a rocky bottom. Destructive interference and increased frictional effects would make a pattern of small charges of similar total explosive mass significantly different than the gas bubble dynamics of a single large explosive mass as described. Thewellman (talk) 07:14, 22 December 2016 (UTC)

The Hedgehog bombs were contact-fuzed which in the North Atlantic effectively meant that if one explodes after entering the water then it has hit a submarine. Only if fired in shallow water would an explosion not signify this, where the bomb hitting the sea floor would also detonate it. Obviously if the sea was this shallow then no U-boat was going to be there in the first place. So you wouldn't bother firing any.

The escort vessels all had Admiralty charts so they knew where the water was deep, and where it was shallow. So did the U-boats. In addition, the escorts were using ASDIC (SONAR).— Preceding unsigned comment added by 95.150.11.196 (talk) 12:15, 16 April 2017 (UTC)