Ironclads and blockade: Britain vs Union

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67th Tigers

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For Lenin's sake, why the 9-inch shell, capable of penetrating the 20 inches of wood would be half-buried?! She would be just simply buried, while not penetrating through! The whole energy of gases would be contained inside the wood; the damage to the construction would be excessive!

(While I must admit, that the "shockwave" is not the best therm to describe the inside-material effect of black powder, but personally I was quite shocked by this "explosive theoteric"!)
Where is the wood "behind" the shell? How is it tamping the explosion?
 

Dilandu

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Where is the wood "behind" the shell? How is it tamping the explosion?
Sigh. Again: it is NOT a kettle! The gases would expand in all sides, because the casting already do the job and raised the pressure up to the limits of cast iron. Rest assured, the pressure capable of shattering the cast iron is perfectly capable to do the same with wood. The breaking strength of cast iron is several times more than of wood, and there isn't enough space around the shell for gases to significanly expand.

Yes, some pressure would be lost through the shell hole. But the distance between sides of the bomb and wood aroud is NOT large enough for the pressure drop to seriously affect the effect on the wood. Activate some common sense: would you be able to contain the black powder explosion by putting the bomb into half-opened paper bag? By your "description", the whole power of gases would went to the way of lesser resistance, and the paper bag would be left intact. I'm sure, that you perfectly understood that this wouldn't happens, thought)

In short: while I admit that I used therm "shockwave" wrong - because I was shocked, actually :smile: - the effect of shell detonation in wood side of the ship would be MUCH worse than penetrating hit.
 

67th Tigers

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No, the gun deck (in name only) on all frigates are unarmed, a remnant when they were small two-deckers. The Royal Navy is the one that started that naming convention. The gun decks on the Merrimack were the upper deck and the spar deck, with an identical unarmed gundeck as Niagara was built. Niagara had one less deck, just the spar deck where the pivots were mounted. The or lop on all frigates and liners is a small half deck right above the hold where the cockpit, magazines, and sickbay were located safe below the waterline.
The source you mentioned earlier gives the dimensions.

The deck of the gundeck is 3 feet above the waterline (26 ft 9 depth of hold at the gun deck minus 23 ft 9 draught), and the deck of the spar deck 9 ft 11 above the waterline. My essential point stands, the gundeck of the Merrimack, and the lower gundeck of the Duncan are of similar heights above the WL by calculating the gundeck height in the same manner. The sills themselves are obviously a bit higher.
 
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Dilandu

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Just let's ask the Dahlgren:

http://quod.lib.umich.edu/m/moa/adh3011.0001.001/227?page=root;rgn=full+text;size=100;view=image

00000227.tif100.png

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I think, this is pretty clear?

The shell LODGED in the side of the ship, and blow the said side apart.

Yes, if the shell penetrated only half its size, or less, the explosion effect would be lessened to the surface effect - as mr. Dahlgren mentioned on the page 214-216. But he also clearly mentioned, that the maximum effect was exactly when the shell was INSIDE the ship's side deep enough to create massive rupture in wood around.

And if the 9-inch shell could penetrate 20 inch out of 32 inch of ship-of-the-line side - this would just be the perfect condition according to Dahlgren.
 

67th Tigers

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Sigh. Again: it is NOT a kettle! The gases would expand in all sides, because the casting already do the job and raised the pressure up to the limits of cast iron. Rest assured, the pressure capable of shattering the cast iron is perfectly capable to do the same with wood. The breaking strength of cast iron is several times more than of wood, and there isn't enough space around the shell for gases to significanly expand.
There is a handy hole for the gases to vent through.

Yes, some pressure would be lost through the shell hole. But the distance between sides of the bomb and wood aroud is NOT large enough for the pressure drop to seriously affect the effect on the wood. Activate some common sense: would you be able to contain the black powder explosion by putting the bomb into half-opened paper bag? By your "description", the whole power of gases would went to the way of lesser resistance, and the paper bag would be left intact. I'm sure, that you perfectly understood that this wouldn't happens, thought)
The bursting charge of a shell is simply enough to break up the shell. These aren't high capacity lyddite shells.

A 9" shell of this type would release 500 liters of gas, some via the fuse hole before the pressure shatters the shell (and if the fuse is "forward" then it would often by extinguished). As the internal pressure exceeds the structural strength of the shell it will shatter (with the broken pieces becoming shrapnel) and the gases of the still burning powder (the still burning powder exiting the shell gives any incendiary effect) will be released into the surroundings.

If in the hull there is a large hole of at least 9 inches for the gas to vent through. That's much, much greater than the diameter required to vent 500 l of gas, and hence the gas will simply vent imparting a slight push to the ship like a rocket.

In short: while I admit that I used therm "shockwave" wrong - because I was shocked, actually :smile: - the effect of shell detonation in wood side of the ship would be MUCH worse than penetrating hit.
Nope, it will vent through the hole made.
 

67th Tigers

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Just let's ask the Dahlgren:
hink, this is pretty clear?

The shell LODGED in the side of the ship, and blow the said side apart.

Yes, if the shell penetrated only half its size, or less, the explosion effect would be lessened to the surface effect - as mr. Dahlgren mentioned on the page 214-216. But he also clearly mentioned, that the maximum effect was exactly when the shell was INSIDE the ship's side deep enough to create massive rupture in wood around.

And if the 9-inch shell could penetrate 20 inch out of 32 inch of ship-of-the-line side - this would just be the perfect condition according to Dahlgren.
Why stop at page 214? Lets see what page 215 and on says....

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So indeed, Dahlgren says that penetration is necessary for maximum effect, and notes that when the round doesn't fully penetrate the effect of the shell is "superficial". He of course is right, but you are not reading him right. He notes what we would now call "cherry picking" of results - picking the absolute best ever achieved and representing them as typical.

The best effects are achieved when the shell has breached the hull before exploding. When the shell doesn't penetrate (i.e. breach the hull) before it deflagrates then it vents out of instead of into the hull.
 
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Dilandu

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Why stop at page 214?
Frankly, I don't know. :smile: Because I mentioned 214-216
So indeed, Dahlgren says that penetration is necessary for maximum effect, and notes that when the round doesn't fully penetrate the effect of the shell is "superficial". He of course is right, but you are not reading him right. He notes what we would now call "cherry picking" of results - picking the absolute best ever achieved and representing them as typical.
--edited-- by moderator jgg

The situation of complete penetration - i.e. when shell came through the side of the ship and exploded inside the hull - is mentioned here:

Dahlgren.png


For some reason, which I failed to understood, you think that "penetration" is the synonim to "came through".

Newsflash: it isn't.

If "somethin was penetrated" it DOESN'T means that some object came completely through. It DOES means that the object came to some depth into the something. And this is clearly what Dahlgren mentions.

You for some reason assumed, that "the least penetration direction" is the direction of the hole.

Newsflash: it isn't

It is the direction where the layer of wood is thinner.

I.e., specially for you, I explain:

- If the shell penetrated the 32-inch wooden side for only 8 inches of depth - then the destructive force would be GENERALLY aimed outward, and we would have the situation, clearly described here:

Dahlgren2.png


I.e. it would be non-penetrating crater.

The "superficial effects" are mentioned in contest of only the single situation:

"when it - the shell - enters no farther than nessesary to remain in the wood". So basically, if the shell is only partially deepened into the wood, and the part of the shell is sticking outside.

- If the shell would go deep in wooden side - for example, for 20 inches out of 32 inches - then the less resistant path would be INWARD. And in that case, the hull of the ship would be penetrated, and the wood around shattered.
 
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Talos

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The source you mentioned earlier gives the dimensions.

The deck of the gundeck is 3 feet above the waterline (26 ft 9 depth of hold at the gun deck minus 23 ft 9 draught), and the deck of the spar deck 9 ft 11 above the waterline. My essential point stands, the gundeck of the Merrimack, and the lower gundeck of the Duncan are of similar heights above the WL by calculating the gundeck height in the same manner. The sills themselves are obviously a bit higher.
Now that I'm home, I can look at my references. Canney cites a letter from Thomas Craven, Niagara's captain, to the Secretary of the Navy, where he says that the guns added to Niagara's gundeck put ports only 5'6" out of the water. That is on a deck about three feet above the waterline and makes perfect sense. The Merrimack and her sisters have a full, additional deck level between their lower ports and the water.

Looking at this photograph of Colorado again, you can see the portholes of the unarmed gundeck/berthing deck below the lower deck of guns. Most of this deck is above the waterline, only the bottom of it dipping below amidships. http://www.museumsyndicate.com/images/8/76128.jpg That's the deck Niagara's guns are installed on and you can see the difference in this picture of her. https://www.history.navy.mil/content/history/nhhc/our-collections/photography/numerical-list-of-images/nhhc-series/nh-series/NH-75000/NH-75895/_jcr_content/mediaitem/image.img.jpg/1459480300678.jpg Remember that those are 5'6" above the water amidships, Colorado's are much higher.

I know that the depth of hold measurement supports three feet in the Franklin Journal, but Benjamin Isherwood, engineer-in-chief of the US Navy, gives the following measurment for Merrimack herself on page 161 of his Experimental Researches in Steam Engineering, Vol 1, page 161. https://books.google.com/books?id=4ClPAAAAYAAJ&dq=merrimack frigate port height&pg=PA161#v=onepage&q=merrimack frigate port height&f=false

"Height of Lower port sills above mean load water-lines, amidships: 9 feet"

Which fits exactly the other information in the Franklin Institute Journal that said 9 feet amidships to the lower ports, 12 feet at the ends. A ship of the line's lower gundeck ports are going to be lower than any frigate's, relative to size. That's the literal nature of their design.
 

chelyabinsk

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Won't somewhere between 4 and 8 do the trick against the un-armed?
The only thing I can think is because Maitland's main concern is losing one of his warships. 20 guns would be the minimum needed to cause problems for most of the Royal Navy ships on station.

Pacific: Bacchante (51), Topaze (51), Termagant (24), Clio (21), Orestes (21), Tartar (20), Camelion (17), Mutine (17), Devastation (6, paddle) ,Geyser (6, paddle)
East Indies and China: Imperieuse (51), Charybdis (21), Pearl (21), Scout (21), Hornet (17), Encounter (14), Odin (16, paddle), Centaur (6, paddle), Sphinx (6, paddle)
Australia: Orpheus (21), Pelorus (21), Fawn (17), Harrier (17), Miranda (15)

Factor in the lower level of crew training, and allow for a proportion of 24pdrs and below among the commerce raiders, and you'd need about 20 guns to take most of these on. However, the likelihood of being able to strengthen a merchant ship's deck sufficiently to mount 20 guns is pretty remote. Certainly most of the converted merchant ships on the blockade historically were ten or less. When you also factor in the shortage of artillery and the lack of bases for even the smallest Union commerce rangers to operate against the British, Maitland seems to have been worried over nothing. Or perhaps he was using the fake threat to rationalise his personal desire to have a crack at San Francisco?

He was vindicated as a result of the sailing sloop Plymouth's experimental cruise in 1857 armed with 4 x IX-inch Dahlgrens and 1 x XI-inch Dahlgren pivot gun in 1857, proving that the heavy guns could be easily handled at sea.
I think we might need to be careful with the term 'proved,' or perhaps 'easily'. Certainly, not everybody was as confident about the merits of Dahlgrens during the war as was their inventor before the war, particularly because gun size is only one of the many components that makes a ship an effective fighting platform:

'The Rinaldo has… more than three times the chance of hitting that this vessel has. The frigate has more than six times as many chances, and although the shot is not as large or as destructive, it will nevertheless go through the ship and kill and wound many men; they would also be enabled to keep up such a continual fire upon the three large guns as to render them useless; and at close quarters, our men having no protection, the enemy’s musketry would be able to prevent their reloading the guns… It is said these guns are intended for distant shooting; but are these vessels so fleet as to enable the commander to choose his distance? No! And if he could, is there sufficient steadiness in the vessel to enable him to fire with any accuracy at a great distance? No! If, on the contrary, there is any sea running at all, it is with imminent danger that he ventures even to cast loose his gun, and the motion is so rapid and violent that he really must be an expert to hit a vessel at the distance of a mile or even half a mile; and in the meantime a small vessel with more stability, more guns, and perhaps more speed, is keeping him close aboard and pouring in broadside after broadside until the leviathan surrenders to a pigmy… I fear that the country will find, should we have a foreign war (when it is too late), that these vessels, armed with the big pivot guns, will be no match for the enemy’s vessels half their size.' (Rear-Admiral Farragut to Secretary of the Navy Gideon Welles, 15 June 1863)

Any attacker with a steamship can run past Fort Point, turn north and either run between Alcatraz and Angel Island, not coming with a mile of the enemy guns, or pass up the Racoon Strait, which is about 100 feet deep, with a partial bar at the south end lowering the water to 29 feet at the minimum.
This was certainly the prospect that kept Brigadier General George Wright of the Department of the Pacific up at night:
'The defences to guard the city of San Francisco against the attacks of hostile steamers have received my most serious consideration. Under cover of the darkness or a fog I have but little doubt that a steamer might pass the two forts without serious injury; at least the chances are decidedly in her favour. Once within the harbour she can take a position beyond the reach of the guns on Alcatraz Island, and, of course, command the city...' (26 January 1863)

Yeah, there are about ca. 70 armed US troops in the area of Fort Point (including those manning the artillery), and the available 500-600 Marines and bluejacket riflemen (sailors were trained to use the rifle musket the same as the infantry).
There is also the militia, which I had occasion to look into a while ago. The report for December 1861 isn't online, but according to the newspapers the governor announced that there were fewer than three thousand arms available (Marin Journal, 18 January 1862); of the seventy-four companies on the list, 'Seven... have been mustered into the service of the United States, while others have had their numbers considerably diminished by their members enlisting in the same service… The Stockton Blues, Sutter Rifles, Sierra Guard, Downey Guard, Sotoyome Guard, and the Humbolt Volunteers, have virtually though not formally disbanded. No arms have been issued to nineteen of the companies known to be organised, while a number of others are only partially armed and equipped. If two thousand five hundred muskets could be mustered out of the number of rank and file upon the rolls, we should be agreeably surprised.' (Sacramento Daily Union, 21 March 1862) Intriguingly, the Sacramento Daily Union was probably closer to the truth than the governor: In the 1863 report, adding up weapons on hand, weapons issued prior to 1 January 1862, and weapons received back in 1863 gives you 2,375.

Wright, in charge of the department of the Pacific, was desperate for weapons for the militia. In October 1862 he begged the Adjutant-General for 20,000 weapons; in December he complained that 'The great difficulty has been the want of arms'; and in January 1863 he asked 'Will the department approve of my issuing small arms to a limited extent to Governor of California to arm organize militia companies in certain localities'? The response from Halleck was no, 'except in cases of extraordinary exigency, when the arms should be merely loaned, to be immediately returned when the exigency has passed'.

The 1863 California Adjutant-General's report reflects these problems. It explains 'We have but a single battery of artillery [in San Francisco, with 2 6pdrs and 2 12pdr howitzers], and but few muskets or small arms of any description, excepting those in the hands of the organised militia,' complains of 'the exposed and defenceless condition of our State,' announces 'California is sadly deficient in arms… We need artillery and cavalry arms, and improved arms for our infantry- of which there are none on this Coast,' and points out that 'Our annual quota amounts to but one hundred and twenty-eight muskets and accoutrements... the number of arms in possession of the state is so small that the most prompt means should be taken to increase the supply, to arm new organisations, and complete the equipment of those already formed.' If arms are a problem, so is organisation: 'The enrolment of the militia has only been partly made. Up to this date, returns have only been received from the Second Brigade and a portion of the First and Sixth brigades, so that not even an approximate return can be made to the President of the United States, as required by the laws of the State of California and the laws of Congress.'

All of these problems can be resolved- and perhaps someone else would be more willing to distribute weapons than was Halleck- but it all takes time.
 
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Dilandu

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It seems that Tiger 67 failed to see the difference between "complete penetration" - i.e. when the shell came through the wood - and "partial penetration" - i.e. when shell only deepened into the wood. He consider EVERY penetration as "shell come through".

He also messed up with the situations, when Dahlgren called the effect "superficial". For some reason, he assumed that ANY non-complete penetration would be "superficial".

In reality, Dahlgren considered "superficial" only the situations, when the shell was barely able to penetrate the hull at all, on the depth no more or less than shell diameter. In his therms - "when it (the shell) merely enters no farther than nessescary for its remaining in wood". I.e. when the part of the shell is sticking out of the hole.

I think, everybody understood, that when 8-inch shell hit the 32-inch wood, there are at least FOUR possible outcomes?

1) The shell came through the whole 32 inch and exploded inside the hull. Complete penetration. In that case - Dahlgren mentioned that personnel losses would be high, but the hull itself would not be seriously damaged (pp. 216-217).

2) The shell came through the majority of wood - for example, 20 inches out of 32 - and exploded inside the wood. Partial penetration. This situation Dahlgren described as optimal (p.p. 213-215), because the energy of expanding gases are directed into the wood, and the wood would shatter, leaving gaping hole in the side (as described on pp. 213-214).

3) The shell came through the minor part of wood - for example, 12 inches out of 32 - and exploded inside the wood. Partial penetration. In that case, the destruction still would be excessive, but it would be more crater than hole - the majority of the blast effect would be directed outward. P.215 clearly described that.

4) The shell came only on the depth of no more - or less - than the shell diameter. For example, 4-8 inches for 8-inch shell. In that case - and ONLY in that case - the gases actually would be vented, and the effect would be "superficial".

So, I think mr. Dahlgren closed those question pretty good. The shell doesn't need to penetrate side completely, to do damage. Moreover, in terms of hull damage, partial penetration is BETTER (while in terms of grew & machinery damage, the complete penetration, of course, is better).

The resulting answer is: the 9-inch shell guns on the 1000 yards would deal the enormous damage agains the ship-of-the-line hull by the partial penetrations. The crew casualties would be less than from complete-penetrating shots, but the hull would be shattered much more effectively. No matter than less crewmembers would be disabled, if the ship itself would be shot into firewood and her sides would be so battered, that they would be unable to mantain structural integrity.

P.S. And, of course, there are such weak spots as gunports, and the ship-of-the-line have plenty of them on relatively short hull...
 
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Talos

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I think we might need to be careful with the term 'proved,' or perhaps 'easily'. Certainly, not everybody was as confident about the merits of Dahlgrens during the war as was their inventor before the war, particularly because gun size is only one of the many components that makes a ship an effective fighting platform:

'The Rinaldo has… more than three times the chance of hitting that this vessel has. The frigate has more than six times as many chances, and although the shot is not as large or as destructive, it will nevertheless go through the ship and kill and wound many men; they would also be enabled to keep up such a continual fire upon the three large guns as to render them useless; and at close quarters, our men having no protection, the enemy’s musketry would be able to prevent their reloading the guns… It is said these guns are intended for distant shooting; but are these vessels so fleet as to enable the commander to choose his distance? No! And if he could, is there sufficient steadiness in the vessel to enable him to fire with any accuracy at a great distance? No! If, on the contrary, there is any sea running at all, it is with imminent danger that he ventures even to cast loose his gun, and the motion is so rapid and violent that he really must be an expert to hit a vessel at the distance of a mile or even half a mile; and in the meantime a small vessel with more stability, more guns, and perhaps more speed, is keeping him close aboard and pouring in broadside after broadside until the leviathan surrenders to a pigmy… I fear that the country will find, should we have a foreign war (when it is too late), that these vessels, armed with the big pivot guns, will be no match for the enemy’s vessels half their size.' (Rear-Admiral Farragut to Secretary of the Navy Gideon Welles, 15 June 1863)
No, the proof was that large-caliber guns could be handled at all at sea. There were concerns that anything bigger than the existing guns would be too cumbersome, but they handled the IX and XI-inch guns on the Plymouth in heavy gales just fine. It wasn't specifically about the Dahlgren pattern of gun at all (though of course Dahlgren talked them up too), it was heavy guns in general. In between praising his own guns in his memoir, of course, Dahlgren alludes to that, that they managed to operate the XI-inch pivot gun, "and without experiencing any of the difficulties usually supposed to render such heavy ordnance nearly unavailable on ship-board". Plymouth, while still armed as such, was one of the ships sent to Cuba with the diplomatic issues with the Royal Navy in 1858.

Farragut's problem was the number of guns and thus rate of fire. His ship, Monogahela, was only armed with two XI-inch Dahlgren pivots, a Parrott rifle, and a few boat howitzers, compared to conventional sloops with 24 or more or 51-gun frigates. That's why he's talking about the chances of hitting with the more numerous smaller guns. Even Dahlgren said that distance shooting past 2000 yards with rifle or smoothbore in a ship is just silly, because of the (three-axis) movement of the ship and also the target.

Remember that the Dahlgrens were first made for ships with conventional broadside batteries like Farragut was yearning for. He just wanted something smaller than those frigates with a conventional battery too, specifically 20 x VIII-inch guns and a pair of Parrotts in the forecastle (because he's fighting in the river when he wrote that) rather than only three guns that were easy to disable. He also complained that because the two pivots were amidships, he couldn't fire them forward. He had two larger ships that were based on broadside batteries in his squadron, but they had a deeper draft that Monogahela, which was why he was flying his flag on her instead. Those of course were the Richmond and the Hartford.

Welles' reply to Farragut was amusing too. It basically boiled down to "your ship was built for speed on the open ocean, not river fighting, so of course it sucks at it." I like the comparison he makes about smaller rapid-firing cannons compared to big pivots: "...one ounce bullet will do more damage than a pound of mustard seed shot".
 

67th Tigers

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Now that I'm home, I can look at my references. Canney cites a letter from Thomas Craven, Niagara's captain, to the Secretary of the Navy, where he says that the guns added to Niagara's gundeck put ports only 5'6" out of the water. That is on a deck about three feet above the waterline and makes perfect sense. The Merrimack and her sisters have a full, additional deck level between their lower ports and the water.
Thanks. The "9 feet" is assuming she made her design draught of 21 ft. She didn't by 2 ft 9 to 3 ft, and hence the sills are that much lower, 6 ft to 6 ft 3 above the WL.

As I said, I was interested simply in showing that the fact that the lower GD of the Duncan is about the same height above the waterline as the Merrimacks only GD. This still hasn't been disputed, as the easily available comparable figures (height of the gundeck above the keel and the draught) show they are about the same.

Personally I don't knew the height of Duncans lower sills, but since the appropriate deck is a similar distance above the WL it is unlikely to be much different.

Had Merrimack not been massively overweight then things may have been different. However she was, and any potential advantage against a 2-decker lost.
 
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Dilandu

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Had Merrimack not been massively overweight then things may have been different. However she was, and any potential advantage against a 2-decker lost.
The main advantage of "Merrimack"-class is the weight of her shell gun salvo, and destructive effect of larger 9-inch and 10-inch shells with their heavier bursting charges over British 8-inch shells.

Now, that we are cleared - with the help of mr. Dahlgren - that the most damaging type of shell hit is a partial penetration of the hull, the situation for HMS "Duncan" in combat is rather bleak. She is inferior in shell gun salvo, her shells are weaker, and her one advantage is that her fuses MAYBE (because we have no actual proofs of that) are more reliable. Her sides would be damaged by heavy "Merrimack" shells much more, than visa versa. I could agree that "Merrimack" might have more onboard casualties, due to more complete penetration by RN shells, but while "Merrimack" would took heavy casualties but still be more or less intact, the "Duncan" would be a wreck (while probably with less casualties :smile: )
 
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Talos

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Thanks. The "9 feet" is assuming she made her design draught of 21 ft. She didn't by 2 ft 9 to 3 ft, and hence the sills are that much lower, 6 ft to 6 ft 3 above the WL.

As I said, I was interested simply in showing that the fact that the lower GD of the Duncan is about the same height above the waterline as the Merrimacks only GD. This still hasn't been disputed, as the easily available comparable figures (height of the gundeck above the keel and the draught) show they are about the same.

Personally I don't knew the height of Duncans lower sills, but since the appropriate deck is a similar distance above the WL it is unlikely to be much different.

Had Merrimack not been massively overweight then things may have been different. However she was, and any potential advantage against a 2-decker lost.
If you look at the rest of the measurements, you'll see that this is for a 23-foot draft. It lists a measure of waterline to rabbit of keel (the top part) as 21 feet, then the keel being a foot deeper at the bow and two feet deeper at the stern. The ship was 9 inches deeper beyond that. As a data point, it also includes the distance of the deck to the gunport, which is 20 inches exactly. Wabash matches up with this, listing the same 21 feet between the top rabbit and waterline, while 30 feet from the rabbit to the gunport lower sill. Still the nine feet Merrimack was cited with.

Duncan's should be a few feet shorter, probably in the range of 6-6.5 feet amidships, which is going to restrict a lot more than Merrimack's, as seen with Niagara's 5'6" level. That's a full foot higher than Victory's ~5 feet, and very good for a 1st rate like Duncan.
 
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chelyabinsk

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So indeed, Dahlgren says that penetration is necessary for maximum effect, and notes that when the round doesn't fully penetrate the effect of the shell is "superficial"...The best effects are achieved when the shell has breached the hull before exploding. When the shell doesn't penetrate (i.e. breach the hull) before it deflagrates then it vents out of instead of into the hull.
What Sir Howard Douglas says is that:
'if the striking velocity and penetrating power be small, the explosive action is rather towards the exterior, on which side the line of resistance is the least, than towards the interior of the ship; and this is the reason why shells that do not strike with considerable horizontal velocity so frequently explode outwards, and throw their fragments back. (See shell experiments of 1838 against the "Prince George" hulk, at 1,200 yards).'

Okay, but this was true for all guns of this weight - see Dahlgren quoting British tests.

Dahlgren further expands that these weren't aimed shots, because the smoke hadn't dispersed and their was no target picture. Same for US guns.
I once tried to track back these tests to the source, but couldn't find them. However, I did find a test at HMS Excellent which was intended to compare 'simultaneous loading' (ramming cartridge, shot and wad together) versus the old system of separate ramming. For 25 rounds, the average time per shot was:

32pdr: 34 seconds old system, 28 seconds new system (39 seconds per Dahlgren)
8in shell gun: 32 seconds old system, 26 seconds new system (42 seconds per Dahlgren)

So, quick as his times seem, they could be quicker- but still inaccurate, of course.

No, the proof was that large-caliber guns could be handled at all at sea. There were concerns that anything bigger than the existing guns would be too cumbersome, but they handled the IX and XI-inch guns on the Plymouth in heavy gales just fine.
But Farragut says 'If, on the contrary, there is any sea running at all, it is with imminent danger that he ventures even to cast loose his gun'. That's unequivocally talking about handling the guns at sea, albeit in a pivot mount rather than a broadside. It also agrees with Commander J.S. Missroon's assessment of the Wachusett that 'Her rolling... is so unusually sharp, quick and deep as to make it doubtful if her battery, especially the XI-inch guns, can be worked, if at all, with any degree of efficiency in an ordinary seaway, the attempt to do so being at the risk of serious casualties to her guns' crews'. Preble said the same thing about the gunboats, which he thought 'cannot use with effect or safety, except in smooth or very moderate weather, their XI-inch pivot gun' as a result of 'their excessive rolling', but that's a much smaller ship in the first place.

As you've pointed out, Farragut is asking for 8in shell guns on the broadside- the largest non-Dahlgren piece available, and the kind fitted to Royal Navy vessels.

Farragut's problem was the number of guns and thus rate of fire... Even Dahlgren said that distance shooting past 2000 yards with rifle or smoothbore in a ship is just silly
I don't think I can agree with your gloss on these comments. When Farragut specifically picks up on the point of accuracy, he says 'the motion is so rapid and violent that he really must be an expert to hit a vessel at the distance of a mile or even half a mile', not 2000+ yards. Part of the reason that British ships retain solid shot is because they expect actions to be fought at longer distances than the Union apparently did: echoes of Valparaiso.

Welles' reply to Farragut was amusing too.
Perhaps, but as Canney points out, what Farragut said does seem to have been taken on board in future designs.

Really, there were two points I wanted to make by highlighting this. Firstly, that what Dahlgren and the authorities considered 'proven' or able to be 'worked easily' was not universal; secondly, that the ability to work a gun was as much about the ship as the gun. Very tempting for us to total up throw weights, or to assume that an overgunned ship is unbeatable: there's generally more to it than that.

Or in 'Bomber Gap' fashion, get more resources allocated to him.
It's possible, but I suspect Maitland realised that travel times meant he was going to war with what he had. It'd be nice to see the full letter, though I doubt it'd be much clearer from reading it what his motivation was in making the claim.
 
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Dilandu

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'if the striking velocity and penetrating power be small, the explosive action is rather towards the exterior, on which side the line of resistance is the least, than towards the interior of the ship; and this is the reason why shells that do not strike with considerable horizontal velocity so frequently explode outwards, and throw their fragments back. (See shell experiments of 1838 against the "Prince George" hulk, at 1,200 yards).'
Exactly the same that mr. Dahlgren stated.

I.e. basically the resulting effect depend of how deep the shell penetrated the wood. Of course, the bursting charge also matters...
 

67th Tigers

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The resulting answer is: the 9-inch shell guns on the 1000 yards would deal the enormous damage agains the ship-of-the-line hull by the partial penetrations. The crew casualties would be less than from complete-penetrating shots, but the hull would be shattered much more effectively. No matter than less crewmembers would be disabled, if the ship itself would be shot into firewood and her sides would be so battered, that they would be unable to mantain structural integrity.
Seems unlikely. BTW you've made up the depths of penetration vs effect - they are not mentioned in Dahlgren.

When it deflagrates the rupturing shell will vent outwards unless the initial burst gives enough force to push shrapnel through the hull. The expanding gases follow the path of least resistance. Dahlgren describes the effects of a 9" shell penetrating 20" into a 30" oak target (at 1,300 yds) and even gives us a picture:

Expired Image Removed
He himself is clear this was an unusually severe effect, as the penetration wasn't deep enough but the explosive charge was large. As you can see gases expanded outwards and little damage was done "inwards". The material fighting power of a ship-of-the-line thus hit would not be large, and it would not have opened the hull.

To do serious damage you need to open a hole into the ships interior first, and preferably get the shell inside. Otherwise the pressure will release through the formed hole.

P.S. And, of course, there are such weak spots as gunports, and the ship-of-the-line have plenty of them on relatively short hull...
Once you have to invoke magic bullets you know you've lost.
 
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67th Tigers

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If you look at the rest of the measurements, you'll see that this is for a 23-foot draft. It lists a measure of waterline to rabbit of keel (the top part) as 21 feet, then the keel being a foot deeper at the bow and two feet deeper at the stern. The ship was 9 inches deeper beyond that. As a data point, it also includes the distance of the deck to the gunport, which is 20 inches exactly. Wabash matches up with this, listing the same 21 feet between the top rabbit and waterline, while 30 feet from the rabbit to the gunport lower sill. Still the nine feet Merrimack was cited with.

Duncan's should be a few feet shorter, probably in the range of 6-6.5 feet amidships, which is going to restrict a lot more than Merrimack's, as seen with Niagara's 5'6" level. That's a full foot higher than Victory's ~5 feet, and very good for a 1st rate like Duncan.
23 ft was designed deep draught. 21 ft was mean designed draught. At mean designed draught the sills were 9 ft above the waterline and the gun sills were 30 ft above the keel.

At the actual 24 ft draught of course the sills are 3 feet lower than the 9 feet they are at 21 ft draught, i.e. 6 feet.

(see here for all these numbers)
 

Dilandu

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Seems unlikely. BTW you've made up the depths of penetration vs effect - they are not mentioned in Dahlgren.
Facepalm.

Sometimes I think you could not read.

When it deflagrates the rupturing shell will vent outwards unless the initial burst gives enough force to push shrapnel through the hull. The expanding gases follow the path of least resistance. Dahlgren describes the effects of a 9" shell penetrating 20" into a 30" oak target (at 1,300 yds) and even gives us a picture:
Sigh. Back to page 215, and read, for this time, not just lie about!


dahlgren2-png.png


Read again the: "an instance of an explosion of this kind is noted at page 229; the penetration wasnot quite sufficient to permit the shell to breach the target through, but as content of powder was large, it was adequate to a deciesive effect, if the object had been a ship; for the whole structure was violently shaken, and the rear timbers, not blown off, were forced asunder several inches, so as to open fair passage to the water"

I.e. the target was holed, and if it was the ship, it would be flooded through the hole.

And the explanation for limited effect is just on the next page:


Expired Image Removed

And this is explanation. The shell hit the END of target, and the energy was released generally to the SIDE. :smile:

Now understood?

Perfect.

He himself is clear this was an unusually severe effect, as the penetration wasn't deep enough but the explosive charge was large. As you can see gases expanded outwards and little damage was done "inwards". The material fighting power of a ship-of-the-line thus hit would not be large, and it would not have opened the hull.
Oh, at least we have progress. Tiger was forced to admit, that the damage would not be zero) Before that he claimed that the damage would be zero)

Of course, the actual result would be much worse, because we would have a large hole in the ship side, and the flooding, if the hole was low enough)

To do serious damage you need to open a hole into the ships interior first, and preferably get the shell inside. Otherwise the pressure will release through the formed hole.
The "preferably" part is nonsence, and you better stop to use this. We now have TWO sources - mr. Dahlgren and Sir Howard Douglas - who said exactly the same about penetration. You just unable to admit that you was wrong, and you are desperatedly trying to "save the face". This is a bad habit; it's much better to admit your mistake, than to disgrace yourself even more by not being able to graps what exactly happened in your own quoted pages :smile:
 
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