Can you sink a submarine with a .50bmg?

[44minimum]

Watching treasure quest last night got me wondering if 50 caliber machine guns would sink a submarine. In those world war two documentarys there are all kinds of footage of airplanes strafing submarines and ships. Can you sink one with a few fifties? How thick is the steel on those? Any submariners here?

And what happens when a depth charge goes off? Are there all kinds of fish floating around afterwards?

[leftiye]

Not to be sarcastic, but if you could, then what are the 18 inch guns for? A fifty will go through 18 inches of concrete a friend told me (not sure I believe that). I would guess however that a sub's pressure hull would be more than a match for a 50, maybe if you just perforated the air/ballast tanks though?

[S.R.Custom]

This too can be calculated. Assumes the occupants are too stupid to plug the hole. What's the depth rating of the sub in question? Anyone know the yield strength of "submarine steel?" I'm guessing it's A6 or similar...

[dubber123]

Are subs pressurized from inside, to equal the outside force of the water? If so, they might not be as thick as you would believe. I think it was post WWII, but I know the test of some 50 BMG armor piercing ammo was something like 4" of steel plate at a 45° angle, at 600 yds. Pretty impressive. I don't think those rounds were available in WWII though.

[Randall]

Not to be sarcastic, but if you could, then what are the 18 inch guns for? A fifty will go through 18 inches of concrete a friend told me (not sure I believe that). I would guess however that a sub's pressure hull would be more than a match for a 50, maybe if you just perforated the air/ballast tanks though?

The 18" guns are for distance, if you can shoot the enemy from 20 miles and he can only shoot 18 miles guess who will win.

[S.R.Custom]

Are subs pressurized from inside, to equal the outside force of the water?

I don't think so. (But I'm no squid.) I would think if they did pressurise the tube, then they'd have to do the slow rise & fall thing to keep from giving everyone inside the bends... Wouldn't be tactically prudent.

[Milanodan]

"Modern" nuke subs are built from a steel called HY80, with a MIN. yield strength of 80,000 PSI. I used to test a lot of it way back ~'66. It's best feature is its toughness at very cold temps--as welded. I used to test it at -60F, and it absorbed a LOT of energy (Charpy V).

But I suspect an AP .50 would penetrate pretty deep, although the hole would be small. Don't know how thick sub hulls are, but HY80 is not armor plate.

I once fired an AP bullet I pulled from some WW2 30/06 ammo, and loaded into a "hot" load fired from a 26" barrel 300 Win. Mag. At close range (way too close) it went right thru a 1 1/8" thick steel plate, but that was soft A36 (YS~36-40KSI).

Then my friend hit the plate with a 270 gr. softnose from his .378 Weatherby, and it made a big hole that almost went thru--it bulged the back of the plate. We measured the hole at 1" deep.

HY80 would stand up far better.

[Wayne Smith]

I know that a B25 with 8 .50BMG's in the nose would sink a destroyer. I don't know how thick the pressure hull on a German or Japanese sub would have been. I also know some of the P38's and B25's in the Pacific were 'over armed' with whatever was available. Some of those included 20mm and 40mm cannon in the nose of the aircraft.

I guess it depends on what the airplane is firing!

[Old Ironsights]

FWIU if you could grab a modern sub, set it in high orbit, & duct-tape on a couple of boosters, the things would make pretty good spaceships too.

Structural and atmospheric integrety are functions of the skin & shape. Punch a hole in the skin and it will collapse under pressure.

Try it with a popcan sometime.

[dubber123]

I don't think so. (But I'm no squid.) I would think if they did pressurise the tube, then they'd have to do the slow rise & fall thing to keep from giving everyone inside the bends... Wouldn't be tactically prudent.

Makes sense, no rapid ascents for sure. For some reason I just doubt those old subs were too thick. If made of mild steel, I doubt even a 4" hull thickness would stop an AP round.

[monadnock#5]

Even if the rounds didn't penetrate the pressure hull, they would still tear up the tanks needed for submerging and more importantly, resurfacing. A sub trapped on the surface was easy meat for the next hunter just over the horizon.

[jonk]

I know that the Tuskeegee airmen sank a German destroyer with nothing but .50 cal ammo and that's a lot harder to do I'd think.

It would be easy to punch a hole in a sub with the .50 but I think it would only do damage to the upper hull- i.e. it could still ride on the surface but you could easily stop them from submerging with enough damage.

No, they don't and didn't pressurize the subs to the pressure at depth. They might run the pressure up a bit to take some of the strain off but not to whatever depth they were at. They needed their compressed air to force the water out of the ballast tanks for a quick surface if need be, not to waste in flooding the cabin of the sub.

FWIW, most WW2 subs in the US fleet were rated to 300-400 feet with crush depth usually around double the rated depth. A few German type VII variants could go down 600 feet as a matter of course and a few even were forced down over 800 feet and lived to tell the tale. Pressure increases by 1 atmospheric pressure (roughly 15 pounds at sea level) about every 33 feet you go down; so at 400 feet for instance, that's about 181 pounds per square inch.

On any given piece of steel, even pig iron, that isn't too high. However the cumulative effect is that it slowly squeezes the hull tighter, reducing the interior volume of the air inside. The quality of the sub's hull isn't so much how strong the steel is but how much flex it can take before it fails. To say nothing of the weld quality, seals aroudn the props, tubes, hatches, etc.

[Johnw...ski]

I don't know about modern submarines but I have been inside of the U-853,
the last German u-boat sunk in WW2. I have gone through the blast holes that were blown open from the depth charges or hedge hogs that got it. The steel of the pressure hull is only about 3/8" thick. The pressure inside of the pressure hull is one atmosphere, same as at sea level, for the exact reason that was stated earlier, the problems associated with decompression when surfacing, the possibility of the bends.

For anyone interested the pressure on the outside of the hull surfaced (and inside) is one atmsphere or about 14.7 psi. For every 33' of depth the pressure increases outside by one atmosphere or 14.7 psi, so at 33' the pressure on the hull is 29.4 psi. The maximum safe depth of the U-853 a type IX C submarine
was 185 to 250 meters, so at a depth of 250 meters the outside pressure would be 380 psi.

Hope this helps,

John

[mike in co]

why ??
yes today hy80 hulls, lite steel balast tanks. over built. some hy 120/160 out there somewhere.
if you put a hole or two in the skin, still surface , and then patch them.
yes lite pressure in the boat, but not"equalizing" at depth.
what you see allows it to float, what you do not see allows it to submerge...deep.
the pressure hull would be hard to hit well, as some has the tanks around it, and then the water...

today it is unlikey a 50 can get with in distance.....too much electronics on the sub.

in wwII while not as strong, still balast tanks, not as deep diving....and a fifty hole would be easy to patch.

the stuff you see is sea water systems failing on the wwII subs, and on some newer. but the isloation of sea water piping from inside the hull means a much more secure interior.

i was on two current and one older for about 8 years.....

i slept well........

in the world there are submarines and there are targets..

the only good marine...is a SUBMARINE!

[44minimum]

Wayne Smith, you stated that you know a B 25 with eight fifties will sink a destroyer and of the other armaments were put on different aircraft. Is this by chance firsthand knowledge, like were you there? If so, then I will bet you have some interesting stories.

[Blammer]

It's not the hole but after it makes the hole what does it bounce around and destroy/damage? :)

Get about 50 of em bouncin around in about 5 seconds an you definitely have some fireworks in the making.

[Leadforbrains]

in the world there are submarines and there are targets..

the only good marine...is a SUBMARINE!

Submariners.... 300 men went down and then later on 150 couples came up.[smilie=s::kidding:

[testhop]

just punch enough holes and it will sink the problum is a sub would dive dive

[35remington]

No, a plane really couldn't prevent a submarine from diving by hitting it with fifties. If the outer hull could be penetrated, it would also have to go through the pressure hull, a rather tall order for a fifty. Even with armor piercing. They could attack the gunners manning the AA guns, though, and kept the decks clear.

In addition, the "sinking the destroyer" bit came about after setting off the unsecured depth charges in the stern or some similar event. Absent some explosives being involved, sinking a fleet destroyer in WWII simply through hull perforations with a fifty is not possible - too many watertight comparments would have to be pierced, necessitating multiple runs on a ship not firing back - which they most assuredly would be.

And yeah, yeah, I've heard about the "awesome firepower" of the B25's complement of fifties in the nose, but the simple fact of the matter was skip bombing was responsible for sinking destroyer sized ships in the vast majority of instances. The multiple passes needed to sink the ship with small caliber fire really aren't in the cards in a combat engagement at a ship firing in return.

The fifties were more capable on the Japanese barge traffic and subchasers encountered. Smaller ships, in other words. People tend to lump many small craft in the category of "destroyer" when they're in actual fact corvette or subchaser size. Hard to judge when you're exchanging fire at 350 mph.

Look up the penetration ratings on fifties; even with AP ammo it's not quite the giant killer many here seem to give it credit for.

The steel used in the pressure hull on German subs was pretty impressive stuff; you could strafe till you were blue in the face (actual events would prevent multiple passes from occuring) and the sub would dive to safety anyway.

That many subs were strafed by fifty caliber fire is a matter of record; I recall no instances, (and I've read quite a bit of WWII history) where strafing passes alone prevented a previously undamaged sub from diving. Whatever damage a fifty can or does do, obviously it wasn't ever sufficient in the time involved to cripple a sub and prevent it from diving.

If there are, I'd appreciate any dissenters showing a link, as I haven't ever heard of it.

[Bret4207]

We also have to remember that in "sinking a destroyer", or anything else for that matter, an awfuul lot depends on what manner of ship or boat you're talking about. A WW1 "Torpedo Destroyer" is a lot different than a WW2 "Tin Can" which is a lot different than a current Destroyer. Some of the early Destroyers and European Destroyers designed in the 20's but used in the early parts of WW2 were little more than single hulled vessels with virtually no armor. They were never designed with air power in mind. Things changed through the decades and what we think of a heavy duty today might have been unimaginable back in the day.

The 50 is an awesome weapon, but as someone else said, it's not a ship sinker.

BTW- The 16" guns of the BB50 class Battleship had a range of about 26 miles IIRC. A 2200 lbs shell passing over the heads of a bunch of pinned down Marines was said to sound, "Like a freight train passing overhead". They may be out dated but there is still a place for them in many Marines minds.

[35remington]

http://www.ww2aircraft.net/forum/aviation/destroyer-sunk-tuskagee-airmen-more-information-needed-1657.html

The supplied link discusses the Tuskegee "destroyer" incident, which was rather inconclusive as to whether the fifties alone even sank the ship at all; conflicting accounts are reported of the event.

The mentioned ship, at around 1100 tons, was too small to be called a destroyer by WWII destroyer standards but normal size for a WWI destroyer; although such Italian ships were rated as good antisubmarine craft, it's a long way from the U.S. Fletcher class destroyer type of WWII, or the equivalent Japanese or German (Z Class) fleet destroyer types.

Yeah, the generic "destroyer" encompasses some rather small types which would be more properly called sloops or corvettes, but any claims of fifties causing fatal damage must take that into account.

The AP 16 inch shells weighed over 2700 lbs. The high capacity (shore bombardment, etc.) shells were closer to a ton.

[Tom Herman]

the stuff you see is sea water systems failing on the wwII subs, and on some newer. but the isloation of sea water piping from inside the hull means a much more secure interior.

Hi Mike,

I can appreciate getting sea water pipes out of the interior of subs.
All I can think of is the Thresher and that disaster. One of my teachers in HS was one of the engineers that designed it.
Needless to say, he had a real bad time getting over the situation, and decided to leave engineering to become a teacher.
The sound picked up by monitors when a sub implodes due to outside pressure must be one of the most sickening sounds around.
Thanks for your service to our country!

Happy Shootin'! -Tom

[No_1]

Old style WW1 subs, I am sure it could be done with a 50 cal. New style subs (1960's on) I seriously doubt it. The design of the modern submarine is pretty much ballast tanks surrounding the pressure hull. There are many ballast tanks on the subs that can work together or independently to submerge or surface the sub. Puncturing 1 or maybe 2 of the 8 or more ballast tanks would have an effect on the performance of the sub but I do not think it would be catastrophic. The pressure hulls use to be made of HY80 but I am not sure what they are made of now. If you are in disagreement, take a look at the below link which shows a picture of a current still active sub which had a "close encounter" with an underwater mountain at speed.
http://www.freerepublic.com/focus/f-news/1330034/posts
As far as pressure goes, as the sub goes deeper in the pressure on the inside rises ever slow slightly because the hull does compress but not enough to make a difference. As far as submerging or surfacing goes, they can do it as fast as it can rise / sink free style or forced under power and it has no ill effect on the crew.

Robert

[danski26]

Ok....FYI...Subs are kept at or around 1 atmospher of pressure inside the boat no matter what depth they are at. In ther words if theboat is 66 ft depth or 600 ft depth the pressure inside is still 14.7 PSI. If you think otherwise....may GOD have mercy on your soul. Now....continue the amusing discussion.

[Zad Fnark]

Not to be sarcastic, but if you could, then what are the 18 inch guns for?

Probably to get through the 11+ inch armored belt of the nearest battleship.

ZF-

[Dale53]

Since others brought it up - The B25 was, at one time, outfitted with a 75mm gun in the nose. I had a close friend (older gentleman) who was a navigator on one. There were definitely some interesting stories connected with that armament.

I read an account of a Wing of B-25's so armed in the South Pacific that hit a battalion of Japanese soldiers at parade. Then the infantry went through the area. Pretty gruesome...

Dale53

[castalott]

This is all from memory and a long time ago....

When I walked thru the U505 in Chicago, I remember the main pressure hull being over an inch thick. The ballast tanks were a lot thinner because they were equal pressure on both sides.

In Herbert Werner's book, "Iron Coffins" , he talks about going deeper than 300 meters several times and being under depth charge attack at the same time. It was a very harrowing experience as the boat would flex and compress with the power of the 300 pound ( and later the 600 pound ) depth charges going off 30 or more feet away. He said it was very loud indeed....And he rode the type vii workhorse model.....

You should read this book. Herbert Werner should not be alive and none of those submariners were wimps...

[35remington]

Now, with a 75mm, all bets are off....although, in reading a history of WWII submarine warfare, I recall where the 3 inch guns on some of the DE's (destroyer escorts, a junior grade destroyer) were not highly thought of as giving good penetration on submarine hulls.

A 75mm gun is approximately 3 inches, and, if speaking of a howitzer like that carried on a B-25, of lower muzzle velocity than the 3 inch (75mm) gun carried on some of smaller escorts. So, more food for thought.

However, the number of subs hit by destroyer gunfire of 3 inch to 5 inch caliber had to be very low. In nearly all instances, when submarines were forced to the surface, they were almost immediately scuttled by their crew in recognition of the superior gunnery power of the converging escort forces. Most gunfire directed at them from the escort ships like DE's and corvettes either missed or did not have time to be used before they went down.

When fired at undamaged, unsuspecting submarines spotted on the surface, it was very rare to get any kind of hit at all before the sub crash dived.

All in all, if shooting at a sub in WW II and knowing I had to penetrate the hull, I'd rather have had a 5 inch 38 (the naval cannon, not a Smith and Wesson).

[Milanodan]

The pressure hulls use to be made of HY80 but I am not sure what they are made of now. Robert

There are stronger grades of the HY (high yield) steels, but I'm not aware of their use in sub hulls. It's possible the Navy spec'd. them--it's been 40+ years since I was involved.

I worked at the Linde weld lab. in Newark, NJ, and we also developed welding processes for the Trident and Minuteman solid fuel rocket motor cases. As I recall, they were made from HY 100/130.

[Frank46]

Treasure Quest had a film on thursday where they were looking to ID some german subs near england. It was mentioned that the pressure hull was 20mm thick. Or about 7/8". I think that they mentioned also it was a type VII sub on one of their dives. Frank

[RugerFan]

WWII US fighters had their wing 50s regulated to hit the same spot at a particular distance. I don’t know about destroyers, but I have read accounts of cargo ships being sunk with concentrated .50 cal fire at the waterline. I never heard of a WWII era sub actually being sunk with 50s, but I would think there may the potential to do so with the concentrated fire of 6 to 8 .50 cals.

[mike in co]

It's not the hole but after it makes the hole what does it bounce around and destroy/damage? :)

Get about 50 of em bouncin around in about 5 seconds an you definitely have some fireworks in the making.


only if you have some magic 50bmg that never looses energy........

penetrate the balast tank shell, big energy loss, then some water cause its not likely you are shooting across at sea level, more energy loss, now its got to attack the pressure hull. at an angle. damaged in the first pc of steel means not likely to make it in to the pressure hull......now after all of this say one makes a hole in the pressure hull......just how much energy is left......and there is tons of stuff for it to hit and loose more energy....its not an empty metal can on the inside.


sorry just not likely.....

mike in co
uss gurnard ssn
uss gurtarro ssn
uss roosevelt ssbn

[mike in co]

Ok....FYI...Subs are kept at or around 1 atmospher of pressure inside the boat no matter what depth they are at. In ther words if theboat is 66 ft depth or 600 ft depth the pressure inside is still 14.7 PSI. If you think otherwise....may GOD have mercy on your soul. Now....continue the amusing discussion.


actually it is just over 1atm....its called "pressure in the boat" always established before shuting the air intake valve and submerging.


mike in co

[mike in co]

Submariners.... 300 men went down and then later on 150 couples came up.[smilie=s::kidding:


cute, nice attempt....gotta get the numbers right...
around 100 on a fast attack 600 class, a little more on the ssbn with a full vertical launch weapons system. on the newer boats that may get a few more...maybe 120 something.

so it goes like this, 120 men and 4 marines went down, and a 124 men came up....

( yes we sometimes took marines on rides...they did not tell us where we were going).....


mike in co

[MT Gianni]

I have read a lot on the ww2 sub battles and missions. In WAHOO, or Clear the bridge, Richard H O'Kane considers a Japanese plane to be a nuisance when they find he has not dropped torpedos. The strafing would only bother thenm if he was lucky enough to hit the scope.
I do have experience with pipe and flaws in a pipe, even a small scrape or indentation will cause it to fail there at pressure and stress. It may not fail at 300 ft depth but any flaw in the hull would add to the stress of the materiels at greater depth.

[WickedGoodOutdoors]

Bubbleheaded Idea. sure just prick the thin mylar skin and it will explode like a midsummersnight dream.


Actually they use items like ASROCs, SUBROCS and such on Subs. Not too much less is going to hurt them.

You do really need to unload your .45 below decks as the ricochette is not good for the electronics. Thats why we had shotguns.

Ill tell you for a Fact that EB Green Duck Tape will hold its own untill you hit 300 feet deep. Its amazaing how much water comes thru a 3 in dia hole!

[klcarroll]

No submarine commander in his right mind would intentionally expose his boat to an aircraft strafing run if he had any options at all! One common point in virtually ALL of the WWII Submarine vs. Aircraft engagements was that the submarine in question was unable to dive for one reason or another.

Even a couple of .50 caliber holes in the pressure hull would restrict diving to no more than periscope depth: ……And then only as an emergency measure.

If you ever have the opportunity to see the U-505 exhibit here in Chicago, you will see for yourself the number of “perforations” she collected during the Boarding Action!


Kent

[mike in co]

Bubbleheaded Idea. sure just prick the thin mylar skin and it will explode like a midsummersnight dream.


Actually they use items like ASROCs, SUBROCS and such on Subs. Not too much less is going to hurt them.

You do really need to unload your .45 below decks as the ricochette is not good for the electronics. Thats why we had shotguns.


http://art.webesteem.pl/14/img/fantazos_submarine_nursery.jpg


and the load was number4 buck( currently available from midway).....the 00 buck was doing too much bouncing on theose steel navy vessels...ships and subs

mike in co

[mike in co]

No submarine commander in his right mind would intentionally expose his boat to an aircraft strafing run if he had any options at all! One common point in virtually ALL of the WWII Submarine vs. Aircraft engagements was that the submarine in question was unable to dive for one reason or another.

Even a couple of .50 caliber holes in the pressure hull would restrict diving to no more than periscope depth: ……And then only as an emergency measure.

If you ever have the opportunity to see the U-505 exhibit here in Chicago, you will see for yourself the number of “perforations” she collected during the Boarding Action!


Kent

since it is unlikely i will be there, where are the perforations....on the exterior skin or visible from the interior. you could repair with a weld. thier real issue was seawater system piping...as intentional holes to the ocean when a fitting or pipe failed.
wwII subs were shallow diving subs.
not like todays deep diving subs

mike in co

[Rattlesnake Charlie]

WWII US Submarine Design Spec
Pressure hull - Thirty-five pound (approx. 7/8") high-tensile steel (HTS)
Outer hull - 3/8" mild steel
Source:
http://www.maritime.org/descon.htm

WWII "fighters" were capable of carrying bombs, which they usually did when supporting ground troops and on submarine patrol.

While it is possible that a .50 could penetrate both superstructure and pressure hull, it is not likely. Punching holes in ballast tanks would not hinder diving, but enough would make staying afloat/surfacing more challening.

I have not heard of any WWII boats being sunk by .50 cal MG fire.

The inside is not pressurized to any degree. It may be pressurized to verify all hull penetrations have closed. We're only talking like your ears popping going up or down mountain.

[35remington]

U-505 was getting shot at by much, much heavier guns than fifties - like automatic antiaircraft cannon mounted on the warships that captured her. These are hardly fifties, possessing from 3 to 10 times the punch and they fire explosive and armor piercing shells of much greater capabilities. Even using these, despite the damage caused, U505 didn't sink because the scuttling attempt went awry and there was insufficient time to accomplish it with the nearby Allied warships.

If the holes these cannon made failed to speed the demise of the U-505, it's pretty hard to make a case that a much less powerful 50 caliber round would sink a sub or prevent it from diving.

Sure, a sub wouldn't knowingly expose itself to a "strafing" run, as the aircraft could be carrying bombs, depth charges, rockets or the like.

But fifties alone really wouldn't be capable of preventing a sub from diving after a strafing run with any possible number of hits. The pressure hull is almost entirely below the water even when the sub is on the surface, and for the small 50 caliber round to penetrate ocean, outer hull, ballast tanks and then finally pressure hull is unlikely.

As actual events showed.

[Leadforbrains]

cute, nice attempt....gotta get the numbers right...
around 100 on a fast attack 600 class, a little more on the ssbn with a full vertical launch weapons system. on the newer boats that may get a few more...maybe 120 something.

so it goes like this, 120 men and went down, and 60 couples came up....



mike in co
Thanks for the correct numbers mike it has been around 20 years since I have heard that saying, so I couldn't remember the joke exactly as it was told to me.
:drinks:

[schutzen]

My father was a USAAF gunner in a B-17s and flew numerous anti-submarine patrols over the Atlantic Ocean. He told me that if they could catch a sub on the surface they would try to atack in a shallow dive from the stern to the bow of the sub. By diving at it they could bring the top turret and the ball turret guns in to action. The machine guns served two purposes. 1st, if the sub was unable to dive the incoming machine gun fire suppressed the sub's deck guns. 2nd, it forced the sub to dive if possible. Then when the bombs were dropped they were more effective. A bomb detonation 50-100 feet from a surfaced sub may not destroy it, but 50-100 feet from a sub submerged at 50-100 feet is much more destructive. Any damage to the hull was incidental to the bomb attack. Sadly, Dad has Alzheimer's disease and can no long converse coherently about his experiences or I would ask him for more details.

[mike in co]

thanks for the correct numbers mike it has been around 20 years since i have heard that saying, so i couldn't remember the joke exactly as it was told to me.
:drinks:



hey lets not be editing my jokes....

Lol
mike

[10-x]

...."even a direct hit with the 100 pound bomb did not guarantee the sinking of a U-boat if its pressure hull was not breached"
....pg 7,Max Schoenfeld's, Stalking the U-Boat, Smithsonian History of Aviation Series, 1995. Excellent book on USAAF Anti-Submarine Warfare in the Atlantic. Aircraft used were B-24's with airborne radar, armed with assorted depth charge type weapons.

[Milanodan]

I do have experience with pipe and flaws in a pipe, even a small scrape or indentation will cause it to fail there at pressure and stress. It may not fail at 300 ft depth but any flaw in the hull would add to the stress of the materiels at greater depth.

Er, not to get too technical here, but one of the basic assumptions of mechanical design is that structural metals are full of small "defects". They may be microscopic in size or much larger. They act to concentrate stresses at or near the defect.

They affect the fatigue-crack resistance far more than the one-time overload condition, and the latter would be the concern for bullet holes/damage during a battle. HY80 has exceptionally good ability to deal with defects (very high fracture toughness), whereas its fatigue strength, even with a minimum of defects, is moderate compared with other higher strength steels.

By definition, fatigue cracking involves repeated cycles of varying stresses (may or may not be reversing stresses), and 100,000 cycles is considered to be about the start of low-cycle fatigue cracking.

[KCSO]

This just happened to be one of my brother's jobs in the Navy. He used a 50 to sink old barges and small ships for artificial reefs. I will ask him Monday just how big of a ship he sunk and how many rounds it took. I never thought to ask before.

[StarMetal]

Here's a 1942 penetration chart for the .50 on amour plate at various distances and angles.

http://img59.exs.cx/img59/9960/ap23wz.jpg

As far for sinking a Destroyer I served aboard a WWII destroyer when I was in the Navy. The hull was only 3/4 inch thick and the main deck was less. I doubt either were armor grade steel. He's another thing to look at. That ship had 600 pound boilers and ran 850 degree superheat. It if were possible to get a .50 into the boiler room, and part of the boiler room had the main deck for an overhead without any 01 level structures above it, and hit one of those superheated steam lines the results would have been disastrous. Most all the super structure on my ship was aluminum bulkheads with steel decks. If a plane came in low across the top of the water and strafed the side of the hull where the boiler rooms resided a .50 with AP would penetrate it. Lots of the hull was just that on that Destroyer, meaning no water or fuel tanks blisters. Of course, just like the subs we speak of, she would be firing back at you.

As an aside we docked in the Destroyer & Submarine piers and I can't count the number of times we were docked very close the USS Scorpian SSN-589. I have pictures of it in fact.

Joe

[35remington]

The short paragraph above the chart sez the penetration is for "20mm Hispano ammunition" (cannon).

That's a whole lot more powerful than a fifty, like 3X.

Here's the whole context, with 20mm Hispano, 50 caliber AP, and a few smaller calibers thrown in for good measure. Scroll down in the posts and read; pictured pages are included.

http://www.ww2aircraft.net/forum/aviation/armor-penetration-20mm-vs-50-cal-911.html

Looks like they've got their own argument going on, theirs about the value of the 50 caliber in ground attack on the Germans in WWII, dragging in all kinds of related and unrelated points about weapon effectiveness. Probably to about the same convincing effect as here. Which is to say everyone has an opinion and hasn't changed it.

Last I checked the Allies won WWII, so at least that isn't up for debate.

[EchoSixMike]

50cal M8API (typically loaded at 4:1 with API-T) is notionally rated at 7/8" penetration of RHA (Roll Hardened Armour) at 100m and zero incidence. RHA is hot rolled 4340 and is typically about 280-330 brinnel hardness IIRC. Vs a sub you're not going to get zero incidence hits however you will pick up some velocity due to aircraft speed. But, you won't have an unobstructed shot at the pressure hull because you'll have to penetrate all the superstructure (ballast tanks, hull framing,etc) 1st.

Hitting any sort of intermediate barrier causes the projectile to tip and thus radically reduce penetration when it actually strikes the main armour belt. This is actually part of the basis for modern armour packages on fighting vehicles like tanks and IFV's with used spaced armour as well as materials like ceramics, kevlar, light metals, rubber/polymers and springs.

FWIW, 50caliber API generally had better penetration of armour at combat ranges than 20mm Hispano SAPHEI. It was more aerodynamic and had higher sectional density WRT it's penetrator core. As mentioned earlier, Allied ships had issues with 3" L/50(barrel length) guns penetrating subs, so 50cal is pretty much out of the question. The one Jap destroyer(actually a DE) that I recall was sunk in the Pacific was due to fire from ready ammo cooking off and starting a fuel fire IIRC, and once the picric acid in the depth charges started burning it blew the stern off. Might very well have been more than one incident like this, as the Japs used destroyers to resupply their forces on the islands quite often.

Some foreign subs use HY100 steel in their hull, and I've seen reference to HY120 in some publications as well. I don't know what US subs use at present, we tend to be a little more discrete with info on our own stuff. S/F.....Ken M

[Lloyd Smale]

I personaly dont think so. Both subs and especialy a boat like a destroyer has bilge pumps that will take care of alot of water leakage. I wouldnt think you could put enough 50 cal holes in a 350 foot long destroyer to sink it. A sub with a hole in it could still submerge. It just couldnt go real deap. Subs and ships constantly leak on there own and have to have bilges pumped daily. At least thats the case with ww2 era stuff.

[StarMetal]

Sorry I grabbed the wrong chart. I'll have to go back see if I can find the Browning .50.

I wasn't talking so much that a .50 cal would sink a Destroyer, but that if a few of the bullets would some how penetrate one of the superheated steam lines a lot of havoc would result. You are correct they have pretty good bilge pumps.

As a side note we went through a hurricane about 280 miles off the eastern coast late at night. I believe it was hurricane Beulah. We took a lot of damage and we came into port bow down as they couldn't pump the water out of the anchor chain locker due to some damage. That will be an adventure I will never forget.

Joe

[corvette8n]

Only if you are using cast[smilie=1:

[35remington]

The penetration chart for the Browning 50 is on the link I posted.

A 20mm Hispano round that tries to do everything, like the semi-armor piercing high explosive incendiary mentioned (SAPHEI) certainly won't outpenetrate a dedicated 50 AP round of WWII since the 20 mm projectile is expected to explode and break up and is structurally weakened by carrying the explosive and incendiary charges. However, the 50 AP falls noticeably short of equivalent 20mm AP ammo of the period when it comes to armor penetration.

Since WWII is the only time we got to test the "penetrate the sub hull theory" we ought to stick to 50 AP ammo that was available at the time when speaking of WWII subs. A modern 50 caliber round, even of enhanced penetration capability, has no chance of penetrating a modern sub hull anyway.

Good discussion anyhow.

Anybody casting a 20mm projectile in ACWW's?

[AZ-Stew]

.50 vs destroyer? Hit a magazine and it's game over for the destroyer. 5" ammo is stored below the water line. Other ammo may be stored above the main deck, depending on the weapon. As others have said, calling a destroyer "lightly armored" is being generous. The ones I served on were aluminum (mostly 1/4", but 3/4" in certain locations) and I wouldn't have wanted to be taking cover from anything but .22 rimfire behind it.

In my opinion, yes, an aircraft could easy sink a destroyer by strafing it with .50s, assuming a couple of hits in the right places. On the other hand, sinking one simply with multiple perforations is not likely.

Regards,

Stew
USS Conyngham DDG-17 1970 - 1974
USS John S. McCain DDG-36 1976 - 1978

[EchoSixMike]

35Rem, the M8API I mentioned is WW2 standard. I've been issued lots dated 1944, unfortunately, that was for use in 1997:???: It's still manufactured, I used a bunch in OIF in 2004, but the current premium API is Mk 211 Raufoss, which has better incendiary components and a tungsten core vice hardened steel in the M8. Mk 211 is typically issued only to air defense units or snipers, I can tell you it does bad things to people when fired from the Barret.

I don't know what was standard issue for ground attack in 20mm in US service in WW2. I strongly suspect it was SAPHEI, but might well have been plain HEI since the main use for 20mm was antiaircraft.

Here's what I pulled off Jane's for the 20x110RB which was used in the 20mm Oerlikon ground mounts, they don't have US data on the 20x110 Hispano but I strongly suspect the same projectiles were used in both cartridges:

Type: HE: Steel shell filled Pentolite or Tetryl, with nose impact fuze Mk 26; 125 g; MV 830 m/s
HEI Mk 3: Steel shell filled Pentolite and incendiary composition; nose impact fuze Mk 26; 125 g; MV 830 m/s
HEI-T Mk 4: As for HEI but with tracer in shell base and reduced filling of high explosive; 123 g; MV 830 m/s
AP-T Mk 9: Solid steel shot, bored at rear for tracer; 120 g; MV 840 m/s

S/F.....Ken M

[StarMetal]

.50 vs destroyer? Hit a magazine and it's game over for the destroyer. 5" ammo is stored below the water line. Other ammo may be stored above the main deck, depending on the weapon. As others have said, calling a destroyer "lightly armored" is being generous. The ones I served on were aluminum (mostly 1/4", but 3/4" in certain locations) and I wouldn't have wanted to be taking cover from anything but .22 rimfire behind it.

In my opinion, yes, an aircraft could easy sink a destroyer by strafing it with .50s, assuming a couple of hits in the right places. On the other hand, sinking one simply with multiple perforations is not likely.

Regards,

Stew
USS Conyngham DDG-17 1970 - 1974
USS John S. McCain DDG-36 1976 - 1978

Aw heck Stew, those were new ships :-D I was aboard the USS Willard Keith DD775, a left over from WWII.

[35remington]

The mentioned post in the link indicated that 20mm AP was superior to 50 AP in armor penetration.

The hulls of all post war and WWII destroyers were steel. The upperworks, especially of several post war classes of destroyers, were often aluminum to reduce top weight and increase stability. Steel was in abundance too in such ships as the Fletcher class; aluminum was used most often in those structures farthest from waterline or that had considerable bulk; the bulkheads and interior passages would present several surfaces that had to be penetrated by any individual round, not a single "paper thin" surface.

After the experience of the Falklands war, aluminum became less popular as a superstructure metal due to its propensity to burn. Certainly the latest destroyer classes use much less of it than formerly.

Setting off a magazine is rather unlikely with a fifty unless top topside ammo in the ready lockers or adjacent to the guns is hit and the fire somehow contributes to ignition of what's stored belowdecks.

"In my opinion, yes, an aircraft could easy sink a destroyer by strafing it with .50s, assuming a couple of hits in the right places." The lottery is winnable, too, it must be said.

Figuring the very great number of destroyers that must have been strafed in WWII, and the very, very small number of them that were recorded to have been lost due to such cause (all incidents I am aware of had to do with igniting depth charges on deck) the chances of actually sinking a destroyer whilst strafing it with a fifty caliber have to, at best, be called "remote." "Assuming a couple of hits in the right places" must have been an overassumption in actual practice. Any individual ship would rarely get subjected to repeated strafing passes - likely, at most, one or two in an engagement. Not good odds for scoring a fatal hit with rounds of limited penetration.

Replicated no doubt dozens upon dozens of times in actual events, strafing wasn't a good way to put a destroyer out of action. This shouldn't be surprising. What "could happen" and what actually "did happen" under combat conditions are certainly proved by the evidence as two entirely different things.

The fifty ain't that big a giant killer. We Americans tend to be overproud of it and give it mythical qualities that surpassed its actual capability in combat, which, while considerable, was really proven to be no more than what it should have been.

Thus, the question, "Can a fifty sink a submarine?" The ony answer is that actual practice proved it cannot.

[StarMetal]

The mentioned post in the link indicated that 20mm AP was superior to 50 AP in armor penetration.

The hulls of all post war and WWII destroyers were steel. The upperworks, especially of several post war classes of destroyers, were often aluminum to reduce top weight and increase stability. Steel was in abundance too in such ships as the Fletcher class; aluminum was used most often in those structures farthest from waterline or that had considerable bulk; the bulkheads and interior passages would present several surfaces that had to be penetrated by any individual round, not a single "paper thin" surface.

After the experience of the Falklands war, aluminum became less popular as a superstructure metal due to its propensity to burn. Certainly the latest destroyer classes use much less of it than formerly.

Setting off a magazine is rather unlikely with a fifty unless top topside ammo in the ready lockers or adjacent to the guns is hit and the fire somehow contributes to ignition of what's stored belowdecks.

"In my opinion, yes, an aircraft could easy sink a destroyer by strafing it with .50s, assuming a couple of hits in the right places." The lottery is winnable, too, it must be said.

Figuring the very great number of destroyers that must have been strafed in WWII, and the very, very small number of them that were recorded to have been lost due to such cause (all incidents I am aware of had to do with igniting depth charges on deck) the chances of actually sinking a destroyer whilst strafing it with a fifty caliber have to, at best, be called "remote." "Assuming a couple of hits in the right places" must have been an overassumption in actual practice. Any individual ship would rarely get subjected to repeated strafing passes - likely, at most, one or two in an engagement. Not good odds for scoring a fatal hit with rounds of limited penetration.

Replicated no doubt dozens upon dozens of times in actual events, strafing wasn't a good way to put a destroyer out of action. This shouldn't be surprising. What "could happen" and what actually "did happen" under combat conditions are certainly proved by the evidence as two entirely different things.

The fifty ain't that big a giant killer. We Americans tend to be overproud of it and give it mythical qualities that surpassed its actual capability in combat, which, while considerable, was really proven to be no more than what it should have been.

Thus, the question, "Can a fifty sink a submarine?" The ony answer is that actual practice proved it cannot.

Don't get the idea that I think a quick strafing fly by is going to take out a Destroyer that is firing back a you. Let me ask you this though. If they had the mini Gatling guns back then, do you think damage from the .50 cal might be more serious?

Joe

[35remington]

Now I have to admit I'm completely hijacking the thread from submarines to something else, so I better keep my replies short, but assuming the dispersion of a gatling gun is less than wing or nose mounted fifties the concentration of fire would be greater....assuming he was lucky enough to get a favorable angle, somehow and the bullet struck squarely instead of at an angle, which is more luck. Maybe increasing the odds of a vital hit? What do I know about that, anyway? I can only be credible in quoting the records of history.....anything else is speculation.

Likely we'll never find out. A fifty, even a gatling gun, mounted in a jet is as obsolete as a biplane. I've already gone far afield in the "then versus now" argument anyway.

I sure wouldn't want to be on any ship's deck with someone shooting at me with six or eight fifties anyway. As if that matters.

[mike in co]

remember as you move from the wwII data...the new subs will not let a airplane get within shooting range they are seen miles away. plenty of time to not be there when the plane shows up.....so it is a invalid question...........you can shoot your gattling/mini gun at the water all you want......

[Crosshair]

Strafing the sub would likely not puncture the pressure hull. What it would do is puncture ballast and fuel tanks. A trail of fuel oil and air bubbles on the surface is not conductive to a subs long term survival.

[Slowpoke]

I was watching a DVD last night and it showed actual footage of U 505 being captured, for a couple a minutes you could barely make out the sub on the surface from all the inbound gun fire both from ship and plane, they said only one crewman was killed, they also said that 800 + (865?) U-boats were sunk.

good luck

[Mtman314]

I took my sub into the ship yards figure more than 6 " of flexible steel. At test depth you can tie a rope across the sub taunt and when it surfaces it will snap.

[pakmc]

I worked in a ship yard for about my first 15 years, we took a destroyer hull and took the forward engine room out and put it into a hull and made a rock dredge out of it. the 6.000 Hp generator ran the cutter head and the 35,000 shaft horse power main engine powered the pump. It could pump up to over 5 miles with out a mid station pump.
But the hull of the "tin can" was only 1/4" plate. Tin cans were light and fast, they were not built to take hits.
A 30-06 could punch holes in one from a mile away. A fifty could punch holes in it from 3miles away. And probabilty go out the other side., but remember the holes are only 1/2" in dia. that's not very big consistering the size of the vessel your punching the holes in. even the 6 or 8 fiftys in the nose of a B-26??(B25)I forget which one it was, would have to put a lot of holes in a destroyer to sink it. (did I say it wouldn't hurt it., no I didn't say that, anything hit with 6 to 8 fiftys was going to be in a world of hurt. (if it survived)
with each gun putting out about 550 rounds a minute, that is a lot of holes to patch.
Pat

[TAWILDCATT]

ANY ONE SEE A B25 WITH A 75 MM gun in left side nose.when attacking a sub often it was at night when the sub was charging its batteries and getting fresh air.to knock it out you put on the carbine arc light and dropped a nose fused depth charge that took care of the guners then a mk 24 mag torpedo,if the sub dove.meanwhile you 50s holed the top.most holes were not 50cal they opend to an inch or so.german subs knew if they dived that MK 24 would get them.so they stayed on top to fight where the sweeper got them.
why do you think the 50 is still popular.AOM3C

[Lloyd Smale]

no doubt stew is right. With a lucky hit it could theroticaly happnen and did on occasion. A bullet will penetrate a hull of even an older ship. I was in the coast guard when i was young and stationed on the cutter taney. This was a DE in ww2 and was built in 34. It was the last ship that was still in commission that fought in pearl harbor. I believe it was decomisssioned in 89. It is now a museam ship in balitimore. If you get there get the attendent to let you down in the engine room. The throttles were valve handles on brass pedestals. The #1 thottle platform still has a 50 cal slug imbedded in it from pearl harbor. This bullet not only penetrated the hull but came down at an angle thorugh another deck and imbedded in the throttle. Might have been a freak incidence but it shows you shouldnt hide behind a couple pieces of steal when a 50 bmg is cut loose!

[castalott]

I have read that 50's were good on surface ships in one respect. Poke as many holes in the funnel as possible. If the boilers won't draw, the ship won't move.

Near the end of WW2, we had just landed in the Phillipines. A large Japanese cruiser/battleship formation surprised a few of our small 'Jeep' carriers with their pitiful over matched destroyer screen. Many of the big Japanese shells went thru the small carriers and exploded beyond. This, and the fact that the Japanese thought these were Essex class, goofed up the range estimation,

The destroyer screen launched a desperate attack to save the carriers. A handful of destroyers made smoke, launched torpedos and tried to blast the paint off the battleships with their guns. After the war,the Jap Admiral in charge claimed he was attacked by a superior force and had to withdraw.

If that Admiral hadn't retreated, he could have been on the landing site in a few hours. He could have destroyed the landing force and lengthened the war by a year or more. ( He could have killed 100,000 or more Americans that day.)

We all need to stand a little straighter and be a little stronger- We are the sons and grandsons of the men that won WW2.

[Beekeeper]

rode them both at one time or another in the Navy.
2100 Destroyers were 1/4 inch aluminim above the main deck and 1/2 steel below the main deck
Boiler and engine rooms had additional 1/4 inch added, wasn't armor plate just 1/4 inch mild steel.
Took 50's through the upper decks but not completely through the hull.

The newer nuke subs are so thick no bullet would penetrete, Even the ballast and fuel tanks are extra thick. Don't think you could penetrate one with a normal shell.

my $.02 worth


beekeeper

[Rattlesnake Charlie]

Wow. This thread has had some interest.

What I want to know, is there anyone with actual documentation that a submarine, WWI or WWII, that was sunk by .50 cal machine gun fire alone.

Additionally, does anyone have documentation on how much HY-80, or Hy-120, a .50 cal can penetrate? Can it do one inch? Two? Just curious.

I have always been interested in firearms.

I have 1.5 yrs submerged experience on 1960 - 1970's vintage US nuke subs.

Never been shot at by a .50 Browning.

[FN in MT]

Somewhat off topic but I recently visited the Mare Island Naval Shipyard in Vallejo, CA. VERY interesting. They opened the yard in 1854 (IIRC) and it closed in the late 1970's. The Museum there is well worth a visit if your ever in the area.

And...If ever in Portland visit the Sub they have downtown at the OHMSI Museum. Great tour, as you actually get to board the Sub and tour the entire vessel.

I've got an Uncle who was on Subs in the North Atlantic I'll call him and see what he thinks.

I've got some Browning fifty time under my belt and there is NO doubt it's a hell of a platform. I've fired quite a few AP & API rds at old US Armor and even at ranges of 2000 yds the old fifty will turn much of a vehicle into swiss cheese.

Interesting topic. Funny too as I just watched "U-571" on the tube yesterday!

FN in MT

[mike in co]

one of the reasons mare island is closed as a sub base, was poor performance. the sunk a brand new sub at the pier!...i toured the resurfaced boat while at nuc school on mare island, and later was assigned to the boat.....one could still find mud if you looked hard in non-critical areas. one very expensive boat...essentially full outfitting twice.
i lived directly across the channel, rode my bicycle to work. ohhh this was 1971!

mike in co

[FN in MT]

Mike in CO,

On Your way to Mare Island.....recall NAPOLI PIZZA?? Rocco the owner is a good friend. Been a LONG time since the pizza shop days for him. Now he owns a nice home and has a couple of Ferrari's! LOL.

I enjoyed the tour of Mare Island. It had to be a hell of a going concern in the WW2 days! Reading the info on a few of the exhibits it was mentioned that the flag that was raised (second raising) over Iwo Jima 64 years ago and captured in that amazing photograph was sewn at the Flag Loft on MI. Interesting stuff.

FN in MT

[Prairie Wolf]

One Question.

Isn't a sub buoyancy negative? The ballast tanks have to be full of air, or it will not float. They let the some of the air out and she becomes basically buoyancy neutral. The depth is then controlled by the steering planes.

Now. All this talk about breaching the pressure hull, why do you need to do that? You only need enough holes in the ballast tanks so you can't hold air so that the sub is buoyancy negative. Then, the sub cannot stop moving or it sinks. I don't know enough to say if the sub is bouyancy negative enough so that no air in the ballast tanks means you are screwed, but I do know it is a very delicate balance.

My brother served on a boomer so next time I talk to him I should ask him.

[No_1]

Good question Prairie Wolf,

I am speaking of somewhat modern subs here:

Subs are built with backup systems on top of backup systems. The ballast tanks are not just 1 tank but are a series of tanks located from front to back. These tanks can operate independently: together or separately and are fed from HP (high pressure) air-paks. I believe you would have to breach the integrity of many tanks in order to have a major effect on the ship's ability to preform.

I know this is thread is base completely on "what-ifs" but you must understand that a sub's main purpose is to stay undetected and it's equipment, crew and rules of operation are honed to the fine edge of staying undetectable. A sub with a good crew will always know pretty much everything that is in the near area and would never show it's face in a situation that would allow it to be compromised. Anything that would have a 50 cal mounted on it would never know the sub was around so it would never get a chance to find out how effective it's 50 cals are against a sub.

Robert

[mike in co]

i think in todays technology, the only way something with a 50 cal would know a sub was around, would be if it was just sunk by said sub.

thier are submarines, and targets...and nothing else....


mike in co

[mike in co]

One Question.

Isn't a sub buoyancy negative? The ballast tanks have to be full of air, or it will not float. They let the some of the air out and she becomes basically buoyancy neutral. The depth is then controlled by the steering planes.

Now. All this talk about breaching the pressure hull, why do you need to do that? You only need enough holes in the ballast tanks so you can't hold air so that the sub is buoyancy negative. Then, the sub cannot stop moving or it sinks. I don't know enough to say if the sub is bouyancy negative enough so that no air in the ballast tanks means you are screwed, but I do know it is a very delicate balance.

My brother served on a boomer so next time I talk to him I should ask him.

read above, plus what he said....plus, plus.....

[Leadforbrains]

I'm no expert, but I have always heard the best way to sink a submarine is by using another submarine.

[missionary5155]

Good morning
I am amazed you Naval historians let the 18" naval cannon mentioned go unanswered.
ONLY the Japs floated battleships (2) armed with 18" rifled ordanance. Our Iowa Class BB carried 9 16" rifled cannons... someone previously noted rounds and range.
It is a fact the PT boat drivers in the South Pacific did everything possible to rearm thier boats with larger caliber weapons finding the caliber.50 lacking in penetration at ranges against jap BARGES and Small craft. I have never read of any PT boats making Caliber .50 runs against jap destroyers or larger combat vessels.
I am a BIG fan of the Caliber .50.. The Army paid me to drive about in 52 Tons and shoot machine guns. Against a light skin vehicle it was awsome. A Caliber .50 would CLEAN the exterior of a search light tank in seconds. But if I needed to sink a Sub ???
God Bless ya

[Rattlesnake Charlie]

My comments, a few up, were:

"What I want to know, is there anyone with actual documentation that a submarine, WWI or WWII, that was sunk by .50 cal machine gun fire alone.

Additionally, does anyone have documentation on how much HY-80, or Hy-120, a 50 cal can penetrate? Can it do one inch? Two? Just curious."

As of 090306, still no response backed up by fact.

Yes, I love speculation, but I live by documented fact.

And, I do like to "stir the pot".

[bearcove]

The easiest way is by hand.

Open the valve to the ballast tanks. DUH!