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Old 04-27-2012, 07:15 AM
kombatminipig kombatminipig is offline
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Shells striking water

One thing I've been pondering about is about battleship shells (vintage WWI-WWII era) striking water, as the vast majority were apt to do during battle. What happens to them?

As to the best of my knowledge, battleships generally fired armor penetrating shells as opposed to HE shells (unless sortied for artillery support), meaning that they wouldn't explode upon impact but that the detonator would go off a fraction of a second later, allowing the heavier shell to penetrate armor before going off. Would striking the water's surface be enough to set off the detonator, and if so would the shell explode on the surface or would it have time to sink? Would the lower impact speeds of plunging fire vs direct fire affect the result?
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Old 04-27-2012, 09:53 AM
Gray Ghost Gray Ghost is offline
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This article goes into some detail on underwater hits with AP shells. The author's consensus is that impact with the water is sufficient to activate the fuze, and therefore the shell will eventually explode if the fuze isn't a dud. Unfortunately, he doesn't cite any figures for that assertion.

I felt the rest of the site has interesting articles on naval gunnery.
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Old 04-27-2012, 10:08 AM
Gray Ghost Gray Ghost is offline
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Piling on, the author in the previous cited piece has another article where he makes the following, unsupported statement:
Quote:
Base fuzes use the impact inertia shock to set them off, so they have to hit something hard enough or thick enough to initiate them; otherwise, the projectile acts like a solid shot until it hits the ground/water, which will set almost all such fuzes off (only a very few special anti-submarine fuzes were ever built that hitting water did not set off--they used either hitting the steel hull of the submarine (fat chance of that at most ranges!) or a depth-charge-like pressure-activated fuze (making them into rather tiny depth charges) and were not very effective, as you might imagine).
Of course, you can have very long delays set for your AP fuzes, as were famously used by the giant 800mm German railway gun "Dora" in the Sevastopol siege, June 6, 1942:
Quote:
[Paraphrased from the translated quote] On June 6, 'Schwere Gustav' [I've read that the 'Schwerer Gustav' referred to the class of 3, later 4 guns, but that it was the gun 'Dora' that fired the shots. Wiki disagrees. W/e] engaged the 'White Cliff' fort. The magazine for the fort was underground and under Severnaya Bay, placed there by the Soviets to be invulnerable to conventional weapons. The Schwere Gustav fired nine shots on the target, penetrating over 30 m (100 feet) of water before entering the bottom and drilling into the concrete to explode inside the warehouse.

Last edited by Gray Ghost; 04-27-2012 at 10:09 AM..
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Old 04-27-2012, 10:52 AM
engineer_comp_geek engineer_comp_geek is online now
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Some people think of water as being fairly soft because you can jump into it from 10 feet up and not get hurt. Once you get above 30 or 40 feet though you can start to get injuries, depending on how the person hits the water. And once you get to a couple hundred feet, it's almost always fatal. Most people who jump from the Golden Gate Bridge don't survive. Water is hard when you hit it fast. High divers can jump from over a hundred feet up and survive though. A lot depends on exactly how you hit.

Similarly, if you shoot a gun into the water, the bullet will often be fragmented just due to the forces involved. The higher the velocity of the bullet, the more likely this is to occur. It seems kinda counter-intuitive, but a .22 bullet will penetrate farther into the water than a .30-06 high powered rifle bullet. The .30-06 will fragment and be scattered, where the .22 will stay intact and go further.

Something like a battleship shell won't fragment like a rifle bullet, but it will certainly hit with enough force to trigger the impact mechanism (whether it is an impact fuse or a delayed type).

While the vast majority of the shells will explode, you can still have some duds. You have to be careful around any old WWI or WWII battle site because there can still be unexploded ordinance in the area, which can still be deadly even after all this time. If you are diving and come across an unexploded WWII shell lying on the sea floor, don't touch it.
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