Does a battleship move in the water when it shoots a full salvo?

swabjocky · February 16, 2002, 10:13 PM

Just a little bit of naval info to let you digest.i know the answer, do you?

swab

Vladimir_Berkov · February 16, 2002, 10:27 PM

I would say no. I am sure that the amount of recoil force generated by the main armament firing is impressive, but likely not enough to make a difference considering the ship's incredible mass.

Also, considering that a full salvo would be fired broadside, the rearward force of the salvo would be dissipated across the entire opposite hull of the ship. The energy required to move the ship side to side is far more than it would take to move the ship forward and backwards considering the same acceleration.

Aion · February 16, 2002, 10:31 PM

Are the screws turning?

- Aion

Coronach · February 16, 2002, 10:35 PM

Yes

-Mike

Scott Conklin · February 16, 2002, 10:36 PM

It depends on what you mean by "move". The force is sufficient to create a wave on the opposite side so the ship has moved, technically.

Ed Brunner · February 16, 2002, 10:39 PM

I don't know anything about naval artillery... I doubt that it would move much , but I would guess that it would move. BTW, in the old fashioned artillery, a salvo is fired one round at a time, not all at once.

Crimper-D · February 16, 2002, 11:07 PM

But have seen a Fletcher Class DD (5 5" mounts) let off all it's mounts at once while underway... that sucker rolled and skidded sideways visibly. Of course, Tin Cans displace considerably less mass than a BB, but I'd say the same principles would apply with both.

bdhawk · February 16, 2002, 11:12 PM

yep, when they touch off the 16 inchers she moved sideways through the water. projectiles weighed 'bout the same as a compact car and they used over 200# of powder for each shot. there is a video of it on the missouri's websight. www.ussmissouri.com

**Mike Irwin** · February 16, 2002, 11:41 PM

Yes. Slightly.

Theoretically, a single person simply PUSHING on a ship, even one as large as the Missouri, should be able to move her if she's not hard tied.

C.R.Sam · February 17, 2002, 12:00 AM

Yep

Tamara · February 17, 2002, 12:25 AM

...huge naval rifles is incredible.

The IJN BB Yamato needed some work after it was determined that the blast from her 18" rifles caused serious damage to the rangefinding optics of her small AA and DP mounts.

Aion · February 17, 2002, 12:42 AM

He already said the screws were turning. So the answer is obviously "yes," whether the ship is rolling as a result of recoil or not.

- Aion

TexasVet · February 17, 2002, 12:47 AM

2000lb Projectile X 2000fps = 4,000,000fpe.
4,000,00fpe X 12 guns = 48,000,000 fpe.
48,000,000 / 2000lb per ton = 24000 TONS of recoil energy!
At 60,000 tons per your average big BB, that is 40% of the mass of the ship being imparted. Bet your bippy it's gonna move. About 6 feet, IIRC.

When I was on a 2,200 ton tin can, we figured the impact of a dud 16 incher (assuming it transferred all its energy) would be the equivalent of holding an identical destroyer two feet off the deck, and dropping it.

**Mike Irwin** · February 17, 2002, 01:14 AM

Uh, TexVet?

I think your calculations are just a little bit off...

By a couple hundred million foot pounds of energy.

Projectile weight for the armor piercing shell was 2,700 pounds.

Multiply that by 7000 grains in a pound, and get 18,900,000 grains projectile weight.

Square the muzzle velocity of 2,500 fps. = 6,250,000.

Multiply weight by MV and get 118,125,000,000,000.

Divide that by the constant 450,400 = 262,266,873 foot pounds of energy.

Divide that by 2,000 to get foot tons of energy = 131,133 foot TONS of energy at the muzzle.

That's for a single gun. Multiply that by 9 for all 9 guns going in unison (which they rarely did because it stressed the ship so much), and you get 1,180,197 foot tons of energy per broadside.

Pretty sobering to think about, eh?

Tam,

You ever wonder where the ship's boats were on Yamato and Musashi?

They had to be stowed in protective recesses under the main deck due to the muzzle blast from the main guns.

herr bean · February 17, 2002, 01:16 AM

Of course it will. If I remember my physics than even shooting a pistol would move it, albeit imperceptably.

C.R.Sam · February 17, 2002, 01:22 AM

Decelerator recoil pad that big?

Sam

Vladimir_Berkov · February 17, 2002, 04:40 AM

First we need to find the force of the guns firing. The weight of one shell is 2,700 pounds. We need to convert this to mass. Weight=mass*acceleration due to gravity. Converting pounds to Newtons and adding gravity we get

12015=mass*9.8

mass=1226kg

Now, force=ma. We need force and acceleration, we have mass.

The length of the 16 gun is 20.32m.

Finalvelocity^2=Initialvelocity^2+(acceleration)(displacement).

(762m/s)^2=0+2a(20.32)

a=14287.5m/s^2

Remember F=ma

So now

F=1226kg*14287.5m/s^2

multiply it by nine guns, and you get

F=157648275 Newtons

Assuming this entire force is transfered to the hull, we can use the same equation to find the acceleration of the hull.

mass of hull=58994285kg

157648275=58994285kg*a

a=2.6722m/s^2

That is not much at all. We also must remember that this is in a frictionless environment. The friction, from both the "suction" action of the side of the hull facing away from the motion, and the resistance of water on the other side, plus the friction produced by the bottom of the hull and of air over the entire portion of the ship above sea level is immense. I have no idea on how to calculate it.

This calculation also disregards any elevation of the guns. If the guns were all fired at a 45 degree angle, the force vectors would result in a force acting both to the side but DOWN as well. Te acceleration side-to-side would be reduced signifigantly.

In addition the guns 48" of rearward recoil movement obviously uses a hydraulic-type system to store much of the recoil energy from the gun barrel. I also have no data on this system and cannot calulate how much it accounts for.

What I would expect is that the ship rotates slightly on its axis if anything, considering the position of the elevated guns relative to the center of mass.

P.S. I was just thinking about this equation, and actually the acceleration number might be wrong as well, as I assumes the shell acceleration as constant, and as reaching max velocity at the exact moment it exits the muzzle of the gun. I also didn't figure in the length of the powder bags, which I do not know.

Art Eatman · February 17, 2002, 05:43 AM

Went on an R&R trip out of Korea to Hong Kong on the USS St. Paul in late 1954. Got to talking gunnery to some navy guys. Aside from, "Yes, a broadside moves the ship sideways.", what I found interesting is that not even a cruiser with "only" 12-inch guns fires straight ahead.

BBs and suchlike angle off course to fire during, say, a stern chase. I don't recall the minimum angle. I was told the reason was to avoid damage to the ship from the recoil.

The St. Paul covered our pullout from Wonsan after the Chosin Reservoir debacle. Part of the outfit I was stationed in had evacuated through there...

(I'll sell my share of Frozen Chosen for a nickel...Okay, do I hear two cents?)

, Art

Vladimir_Berkov · February 17, 2002, 08:52 AM

These sites, however, state otherwise.

http://www.battleship-newjersey.org/.../23septpm.html

Quote:

QUESTION -- I noticed in an aerial photo of the NEW JERSEY firing a broadside that the water next to the ship is roiled. Do the guns cause that or does the ship move sideways after firing a broadside?

The ship does not move. The roiled water is caused by the concussion of the guns firing.

http://www.warships1.com/W-Tech/tech-022.htm

Quote:

What looks like a side-ways wake is just the water being broiled up by the muzzle blasts. The ship doesn't move an inch or even heel from a broadside.

The guns have a recoil slide of up to 48 inches and the shock is distributed evenly through the turret foundation and the hull structure. The mass of a 57,000 ton ship is just too great for the recoil of the guns to move it. Well, theoretically, a fraction of a millimeter.

But because of the expansive range of the overpressure (muzzle blast), a lot of the rapidly displaced air presses against the bulkheads and decks. Those structures that are not armored actually flex inwards just a bit, thus displacing air quickly inside the ship and causing loose items to fly around. Sort of like having your house sealed up with all windows and vents closed and when you slam the front door quickly the displaced air pops open the kitchen cabinets.

R. A. Landgraff

Art Eatman · February 17, 2002, 09:58 AM

Given the 2,700 lb/projectile, that's roughly 12 tons for a 9-gun broadside. 57,000 tons of ship means roughly 1/5,000th of its mass leaving home rapidly.

Okay, 1/5,000th of the mass of a 190-pound man on an innertube in a pond, with a 10-pound rifle, firing a 280-grain bullet: Roughly equal mass:mass comparison test.

Somebody with a .375, come warmer weather, you mission is...

, Art

Jager1 · February 17, 2002, 10:01 AM

I remember when the New Jersey was shelling positions in Lebanon, there was much ado about her having to stage salvoes to encompass the "rocking effect" and sideways displacement when firing. IIRC, the media claimed it was something along the order of 12 feet with the guns elevated at 45 degrees?

Vladimir_Berkov · February 17, 2002, 10:12 AM

The reason why battleships do not fire multiple turrets at once, is not because of displacement, but because the firings are not perfectly simultanious, the very slight "rocking" effect of the the firing on the lateral axis of the ship screws with the firing computer solutions ever so slightly. However, that would translate to a big error over a long distance.

Guys, think about it logically. If the ship moved 12 feet to the side when the guns fired, people would be knocked off their feet all over the ship. It would be like an earthquake going on inside. Even a relativly small acceration of the ground under a standing human can be very disruptive. Have you ever stepped on one of those moving sidewalks, or even an escalator when you weren't paying attention?

The force of the firing is rapidly transfered to the water from the hull, if moving sideways. That would mean that the movement of 12 feet would require a very quick acceleration and hence a violant disturbance all over the ship.

Double Naught Spy · February 17, 2002, 10:14 AM

Given that the battleship is not securely fixed as a solid object, then one of the basic rules of physics would apply. For every action, there is an opposite and equal reaction.

If there is enough force to rock the ship, then it is being moved in the water.

It doesn't get any more simple than than.

swabjocky · February 17, 2002, 10:33 AM

Well people, the russians did win this gold medal.from what i read on the usnavy internet site,the ship doesnot move.the shock is absorbed by hydrolics.mr vlademir has it right.

swab

Vladimir_Berkov · February 17, 2002, 10:57 AM

Right on! Where is my prize?

February 16, 2002, 10:13 PM	#1
swabjocky Senior Member Join Date: August 27, 2001 Location: upstate sc Posts: 384	Does a battleship move in the water when it shoots a full salvo? Just a little bit of naval info to let you digest.i know the answer, do you? swab

February 16, 2002, 10:35 PM	#4
Coronach Senior Member Join Date: March 25, 1999 Posts: 3,147	Yes -Mike __________________ The axe bites into the door, ripping a hole in one panel. The maniac puts his face into the hole, cackling gleefully, "Here's Johnny...erk." "And here's Smith and Wesson," murmurs Coronach, Mozambiquing six rounds of .357 into the critter at a range of three feet. -Lawdog "True pacifism is the finest form of manliness. But if a man comes up to you and cuts your hand off, you don't just offer him the other one. Not if you want to go on playing the piano, you don't." -Sam Peckinpah "A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects." -Robert Heinlein

February 16, 2002, 10:36 PM	#5
Scott Conklin Senior Member Join Date: November 18, 2000 Location: B.F.E. Posts: 1,721	Actually... It depends on what you mean by "move". The force is sufficient to create a wave on the opposite side so the ship has moved, technically. __________________ "Once the monkeys learn they can vote themselves bananas, they'll never climb another tree." - Heinlein www.libertydwells.com

February 16, 2002, 10:39 PM	#6
Ed Brunner Senior Member Join Date: October 11, 1998 Location: Natchez, MS, USA Posts: 2,562	This is only a guess... I don't know anything about naval artillery... I doubt that it would move much , but I would guess that it would move. BTW, in the old fashioned artillery, a salvo is fired one round at a time, not all at once. __________________ MOLON LABE UNTIL IT'S OVER! Ed

February 16, 2002, 11:07 PM	#7
Crimper-D Senior Member Join Date: July 26, 2001 Location: The Bearflag Republic Posts: 579	Don't know about the BB's... But have seen a Fletcher Class DD (5 5" mounts) let off all it's mounts at once while underway... that sucker rolled and skidded sideways visibly. Of course, Tin Cans displace considerably less mass than a BB, but I'd say the same principles would apply with both. __________________ "It is evident that scepticism, while it makes no actual change in a man, always makes him feel better.".....H.L.Mencken

February 16, 2002, 10:27 PM	#2
Vladimir_Berkov Senior Member Join Date: September 1, 2001 Posts: 378	I would say no. I am sure that the amount of recoil force generated by the main armament firing is impressive, but likely not enough to make a difference considering the ship's incredible mass. Also, considering that a full salvo would be fired broadside, the rearward force of the salvo would be dissipated across the entire opposite hull of the ship. The energy required to move the ship side to side is far more than it would take to move the ship forward and backwards considering the same acceleration.

February 16, 2002, 10:31 PM	#3
Aion Senior Member Join Date: January 27, 2002 Location: Northern Virginia Posts: 277	Are the screws turning? - Aion

February 16, 2002, 11:12 PM	#8
bdhawk Junior member Join Date: December 22, 2000 Posts: 114	uss missouri yep, when they touch off the 16 inchers she moved sideways through the water. projectiles weighed 'bout the same as a compact car and they used over 200# of powder for each shot. there is a video of it on the missouri's websight. www.ussmissouri.com

February 16, 2002, 11:41 PM	#9
Mike Irwin Staff Join Date: April 13, 2000 Location: Northern Virginia Posts: 41,380	Yes. Slightly. Theoretically, a single person simply PUSHING on a ship, even one as large as the Missouri, should be able to move her if she's not hard tied. __________________ "The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza Baby Jesus cries when the fat redneck doesn't have military-grade firepower.

February 17, 2002, 12:00 AM	#10
C.R.Sam Senior Member Join Date: October 29, 1999 Location: Dewey, AZ Posts: 12,858	Yep

February 17, 2002, 12:25 AM	#11
Tamara Moderator Emeritus Join Date: March 11, 2000 Location: Indianapolis, IN Posts: 16,002	The muzzle blast of these... ...huge naval rifles is incredible. The IJN BB Yamato needed some work after it was determined that the blast from her 18" rifles caused serious damage to the rangefinding optics of her small AA and DP mounts. __________________ MOLON LABE! 2% Unobtainium, 98% Hypetanium. The Arms Room: An Online Museum.

February 17, 2002, 12:42 AM	#12
Aion Senior Member Join Date: January 27, 2002 Location: Northern Virginia Posts: 277	He already said the screws were turning. So the answer is obviously "yes," whether the ship is rolling as a result of recoil or not. - Aion

February 17, 2002, 12:47 AM	#13
TexasVet Senior Member Join Date: July 22, 2000 Location: DeepEastTexas Posts: 1,096	Oh yeah! 2000lb Projectile X 2000fps = 4,000,000fpe. 4,000,00fpe X 12 guns = 48,000,000 fpe. 48,000,000 / 2000lb per ton = 24000 TONS of recoil energy! At 60,000 tons per your average big BB, that is 40% of the mass of the ship being imparted. Bet your bippy it's gonna move. About 6 feet, IIRC. When I was on a 2,200 ton tin can, we figured the impact of a dud 16 incher (assuming it transferred all its energy) would be the equivalent of holding an identical destroyer two feet off the deck, and dropping it. __________________ Tonkin Gulf Yacht Club 68-70 You are What you do When it counts.

February 17, 2002, 01:14 AM	#14
Mike Irwin Staff Join Date: April 13, 2000 Location: Northern Virginia Posts: 41,380	Uh, TexVet? I think your calculations are just a little bit off... By a couple hundred million foot pounds of energy. Projectile weight for the armor piercing shell was 2,700 pounds. Multiply that by 7000 grains in a pound, and get 18,900,000 grains projectile weight. Square the muzzle velocity of 2,500 fps. = 6,250,000. Multiply weight by MV and get 118,125,000,000,000. Divide that by the constant 450,400 = 262,266,873 foot pounds of energy. Divide that by 2,000 to get foot tons of energy = 131,133 foot TONS of energy at the muzzle. That's for a single gun. Multiply that by 9 for all 9 guns going in unison (which they rarely did because it stressed the ship so much), and you get 1,180,197 foot tons of energy per broadside. Pretty sobering to think about, eh? Tam, You ever wonder where the ship's boats were on Yamato and Musashi? They had to be stowed in protective recesses under the main deck due to the muzzle blast from the main guns. __________________ "The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza Baby Jesus cries when the fat redneck doesn't have military-grade firepower.

February 17, 2002, 01:16 AM	#15
herr bean Member Join Date: February 16, 2002 Location: Colorado Springs, CO Posts: 31	Of course it will. If I remember my physics than even shooting a pistol would move it, albeit imperceptably.

February 17, 2002, 01:22 AM	#16
C.R.Sam Senior Member Join Date: October 29, 1999 Location: Dewey, AZ Posts: 12,858	Decelerator recoil pad that big? Sam

February 17, 2002, 04:40 AM	#17
Vladimir_Berkov Senior Member Join Date: September 1, 2001 Posts: 378	First we need to find the force of the guns firing. The weight of one shell is 2,700 pounds. We need to convert this to mass. Weight=massacceleration due to gravity. Converting pounds to Newtons and adding gravity we get 12015=mass9.8 mass=1226kg Now, force=ma. We need force and acceleration, we have mass. The length of the 16 gun is 20.32m. Finalvelocity^2=Initialvelocity^2+(acceleration)(displacement). (762m/s)^2=0+2a(20.32) a=14287.5m/s^2 Remember F=ma So now F=1226kg14287.5m/s^2 multiply it by nine guns, and you get F=157648275 Newtons Assuming this entire force is transfered to the hull, we can use the same equation to find the acceleration of the hull. mass of hull=58994285kg 157648275=58994285kga a=2.6722m/s^2 That is not much at all. We also must remember that this is in a frictionless environment. The friction, from both the "suction" action of the side of the hull facing away from the motion, and the resistance of water on the other side, plus the friction produced by the bottom of the hull and of air over the entire portion of the ship above sea level is immense. I have no idea on how to calculate it. This calculation also disregards any elevation of the guns. If the guns were all fired at a 45 degree angle, the force vectors would result in a force acting both to the side but DOWN as well. Te acceleration side-to-side would be reduced signifigantly. In addition the guns 48" of rearward recoil movement obviously uses a hydraulic-type system to store much of the recoil energy from the gun barrel. I also have no data on this system and cannot calulate how much it accounts for. What I would expect is that the ship rotates slightly on its axis if anything, considering the position of the elevated guns relative to the center of mass. P.S. I was just thinking about this equation, and actually the acceleration number might be wrong as well, as I assumes the shell acceleration as constant, and as reaching max velocity at the exact moment it exits the muzzle of the gun. I also didn't figure in the length of the powder bags, which I do not know.

February 17, 2002, 05:43 AM	#18
Art Eatman Staff in Memoriam Join Date: November 13, 1998 Location: Terlingua, TX; Thomasville, GA Posts: 24,798	Went on an R&R trip out of Korea to Hong Kong on the USS St. Paul in late 1954. Got to talking gunnery to some navy guys. Aside from, "Yes, a broadside moves the ship sideways.", what I found interesting is that not even a cruiser with "only" 12-inch guns fires straight ahead. BBs and suchlike angle off course to fire during, say, a stern chase. I don't recall the minimum angle. I was told the reason was to avoid damage to the ship from the recoil. The St. Paul covered our pullout from Wonsan after the Chosin Reservoir debacle. Part of the outfit I was stationed in had evacuated through there... (I'll sell my share of Frozen Chosen for a nickel...Okay, do I hear two cents?) , Art

February 17, 2002, 09:58 AM	#20
Art Eatman Staff in Memoriam Join Date: November 13, 1998 Location: Terlingua, TX; Thomasville, GA Posts: 24,798	Given the 2,700 lb/projectile, that's roughly 12 tons for a 9-gun broadside. 57,000 tons of ship means roughly 1/5,000th of its mass leaving home rapidly. Okay, 1/5,000th of the mass of a 190-pound man on an innertube in a pond, with a 10-pound rifle, firing a 280-grain bullet: Roughly equal mass:mass comparison test. Somebody with a .375, come warmer weather, you mission is... , Art

February 17, 2002, 10:01 AM	#21
Jager1 Senior Member Join Date: December 11, 2000 Location: Phoenix, Arizona Posts: 422	I remember when the New Jersey was shelling positions in Lebanon, there was much ado about her having to stage salvoes to encompass the "rocking effect" and sideways displacement when firing. IIRC, the media claimed it was something along the order of 12 feet with the guns elevated at 45 degrees?

February 17, 2002, 10:12 AM	#22
Vladimir_Berkov Senior Member Join Date: September 1, 2001 Posts: 378	The reason why battleships do not fire multiple turrets at once, is not because of displacement, but because the firings are not perfectly simultanious, the very slight "rocking" effect of the the firing on the lateral axis of the ship screws with the firing computer solutions ever so slightly. However, that would translate to a big error over a long distance. Guys, think about it logically. If the ship moved 12 feet to the side when the guns fired, people would be knocked off their feet all over the ship. It would be like an earthquake going on inside. Even a relativly small acceration of the ground under a standing human can be very disruptive. Have you ever stepped on one of those moving sidewalks, or even an escalator when you weren't paying attention? The force of the firing is rapidly transfered to the water from the hull, if moving sideways. That would mean that the movement of 12 feet would require a very quick acceleration and hence a violant disturbance all over the ship.

February 17, 2002, 10:14 AM	#23
Double Naught Spy Senior Member Join Date: January 8, 2001 Location: Forestburg, Montague Cnty, TX Posts: 12,717	Given that the battleship is not securely fixed as a solid object, then one of the basic rules of physics would apply. For every action, there is an opposite and equal reaction. If there is enough force to rock the ship, then it is being moved in the water. It doesn't get any more simple than than. __________________ "If you look through your scope and see your shoe, aim higher." -- said to me by my 11 year old daughter before going out for hogs 8/13/2011 My Hunting Videos https://www.youtube.com/user/HornHillRange

February 17, 2002, 10:33 AM	#24
swabjocky Senior Member Join Date: August 27, 2001 Location: upstate sc Posts: 384	ship movement. Well people, the russians did win this gold medal.from what i read on the usnavy internet site,the ship doesnot move.the shock is absorbed by hydrolics.mr vlademir has it right. swab

February 17, 2002, 10:57 AM	#25
Vladimir_Berkov Senior Member Join Date: September 1, 2001 Posts: 378	Right on! Where is my prize?