Ironclad A Very Small Number of Monitors Defeated the Confederacy

The Moorsom system was installed in HMS Terror, and can still be seen in HMS Warrior where each gun port is marked up with the angles of divergence / convergence from the "controlling" broadside gun. Her first Captain, Arthur Cochrane had it installed.
 
As the RN had learned from the Russians, wooden vessels could not withstand modern cannon fire. The Monitor used 1/2 charges because her guns had not been proofed. Later practice showed that full charges would have knocked the Virginia to tatters. Everybody was making it up as they went along back then.

A very real element that Sap does not consider is the effect of temperature on the metal ships of that era were made of. You will need to do as I did & have metallurgical engineer explain this. In simple terms, the armor plate when cold soaked to a very low temperature has the physical qualities of glass. That is not a figure of speech. Like the gunboats at Ft Donelson, when struck armor plate shattered. Hanging out around Halifax from fall to spring would have been imprudent.
Oh dear, not again. Monitors 11" guns WERE firing full service charges, the 11" Dahlgren SB could not have achieved penetration of Virginia's armour. The James town island tests showed that 2 x 2" plate over 24" properly supported backing was the equivalent of 5.5" solid plate if vertical and at 40 degrees inclination 6.79" plate.
In contrast the Monitor's turret armour made up of laminated .75" - 1" plates to a thickness of 8 -9" with no backing, would by the Woolwich tests at Plumstead and Shoeburyness be equivalent to 5.4" plate at best. Had Virginia carried the 7" and 6.4" steel point shot at second Hampton Roads with which she was subsequently equipped, the story could have been very different.
 
Since this is March 1861, the Magenta and Solferino haven't even been launched when he's making these worried statements.
As a point of interest, I should note that the Magenta and Solferino - like the Gloire and the British Prince Consort - were wooden hulled. This is why they had complete iron protection in all cases, it's because the wooden hull can't be subdivided and so damage to the ends means leaking that can spread through the whole ship.
The Warrior, as an iron hulled ship, was subdivided into compartments for protection and so did not strictly require a waterline belt to retain her fighting capabilities.


The James town island tests showed that 2 x 2" plate over 24" properly supported backing was the equivalent of 5.5" solid plate if vertical and at 40 degrees inclination 6.79" plate.
In contrast the Monitor's turret armour made up of laminated .75" - 1" plates to a thickness of 8 -9" with no backing, would by the Woolwich tests at Plumstead and Shoeburyness be equivalent to 5.4" plate at best.
Comparison of penetration, using Fairbairn formula for wrought and Noble for steel:

Dahlgren 11"
15 lbs powder (cannot find value)
20 lbs powder 1038 fps
30 lbs powder (limit of gun endurance) 1400 fps

Wrought iron shot (cast performs less well)
Just over 3" solid plate penetration at 20 lbs powder
4.2" solid plate penetration at 30 lbs powder

Cannot penetrate Virginia or Monitor (or Warrior)


Dahlgren 15"
60 lbs powder 1230 fps

Wrought iron shot
5.1" solid plate penetration at 60 lbs powder
Cannot penetrate Virginia or Monitor (but comes close for Monitor), or Warrior
(Would penetrate all three with cast steel shot)


68 pounder
16 lbs powder (normal charge) measured at 1600 fps
20 lbs powder (battering charge) had one result of 2040 fps, but ~1800 fps more typical

Wrought iron shot
3.6" penetration at 16 lbs powder
4-4.5" penetration at 20 lbs powder
Cannot penetrate any of the discussed ships

Steel shot
6.1" penetration at 16 lbs powder
6.9-7.6" penetration at 20 lbs powder
Penetrates all three ships

The Somerset cannon was somewhat better than the 68 pounder.

The 7" guns penetrate a bit better with Palliser than the Somerset/68 pounder guns with cast steel shot, but of course Palliser is AP shell and so you have an explosion either behind the armour or inside it. The bursting charge is small, though.


It's also worth pointing out the massive weight penalty involved with not backing a system of armour. The Virginia system has 4" of iron and 24" of oak, and 10" of oak is about equivalent in density to 1" of iron, which means that the Virginia system is "like" having the equivalent thickness of 6.4" of iron for protection in weight terms. Monitor's turret meanwhile has worse protection but weighs over 20% more per square foot of armour (and of course doesn't stop spalling).


ED: also of note is that the iron quality of Monitor's turret is not very good. It's got high silica content and is comparable to cast iron, not wrought; this would make penetration more likely.
 
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The Moorsom system was installed in HMS Terror, and can still be seen in HMS Warrior where each gun port is marked up with the angles of divergence / convergence from the "controlling" broadside gun. Her first Captain, Arthur Cochrane had it installed.
That sounds like the system created by the captain of HMS Shannon. He had years to work up his crew. Aiming angles were carved into the deck & groups of guns aimed at a single gun port. A pendulum sight was used. The fire three broadsides from pistol range & board in the smoke mentality of RN captains did not allow for general adoption of such a rational system.
 
Oh dear, not again. Monitors 11" guns WERE firing full service charges, the 11" Dahlgren SB could not have achieved penetration of Virginia's armour. The James town island tests showed that 2 x 2" plate over 24" properly supported backing was the equivalent of 5.5" solid plate if vertical and at 40 degrees inclination 6.79" plate.
In contrast the Monitor's turret armour made up of laminated .75" - 1" plates to a thickness of 8 -9" with no backing, would by the Woolwich tests at Plumstead and Shoeburyness be equivalent to 5.4" plate at best. Had Virginia carried the 7" and 6.4" steel point shot at second Hampton Roads with which she was subsequently equipped, the story could have been very different.
I believe that the experience of the gunboats at FT Donelson provides a real world example of what actually happened in combat. Plunging fire hitting the unarmored roof did great damage. It was balls entering through open gun ports that sent balls bounding around the gun deck. The low temperature caused the armor plate to shatter like glass. Another factor was the unique nature of the balls being fired.

The large cannon did not have any solid shot. The gun crews, who had never even seen one of things, let alone fired one came up with a novel solution. The empty shells were filled with molten lead. I have no idea what they weighed, but it had to be considerable. Instead of bouncing off like a solid ball, the lead filled shells broke open & splatted like a snowball. Nobody ever tested it in a controlled way. It would be intriguing to find out how effective lead filled shells might have been. Bench tests & actual experience are often very different things.
 
That sounds like the system created by the captain of HMS Shannon. He had years to work up his crew. Aiming angles were carved into the deck & groups of guns aimed at a single gun port. A pendulum sight was used. The fire three broadsides from pistol range & board in the smoke mentality of RN captains did not allow for general adoption of such a rational system.
That is an exceptionally stereotyped view, since the Moorsom director was to my understanding issued widely (it was introduced 1850) and the mentality you describe is not in evidence during engagements in this period.
 
I believe that the experience of the gunboats at FT Donelson provides a real world example of what actually happened in combat. Plunging fire hitting the unarmored roof did great damage. It was balls entering through open gun ports that assent balls bounding around the gun deck. The low temperature caused the armor plate to shatter like glass. Another factor was the unique nature of the balls being fired.
This is an argument that the monitor would be essentially useless in combat, because it focuses specifically on plunging fire and the Monitors were both very poorly armoured against plunging fire and easily disabled in the event of taking damage to the deck - water would come in easily.
 
The fire three broadsides from pistol range & board in the smoke mentality of RN captains did not allow for general adoption of such a rational system.
So something that I thought might be helpful was that, in the past, I've seen the regulations for gunnery in the US and British service at the time in question.


Here's an excerpt from the British one.


'Men in Sea-going ships are to be encouraged to qualify themselves for "Acting Captain of Gun" under the instruction of the Gunnery Officer, in which case they need only be required to be perfect in the first three instructions, but each man before receiving his certificate must have fired at least the following number of rounds, and have proved that he can lay a gun quickly, and is a good and efficient shot:-
120 rounds from a rifle at objects distant from 200 to 800 yards...
20 rounds from a revolver pistol
30 rounds from a 6-pounder short practice gun, half being with motion
10 rounds from a great gun, half being with motion
On their arrival in England to pay off, they must pass through one of the Gunnery Ships to be confirmed in their present certificate, or to qualify for a higher grade.'
(Instructions for the exercise and service of great guns, etc., on board her majesty's ships, 1858)

The same manual gives instructions for how to use Moorsom's Director, which means that it was at the very least official equipment.

What this means is that a gun captain in British service has experience at estimating range, and dealing with both practice guns and big guns including firing at motion. Moorsom's Director is official equipment.


And here's from the US one (1860 manual).


279. Officers of divisions and Captains of guns should be occasionally practised in measuring the distances of objects by the eye, at times when opportunities offer of verifying the accuracy of their estimate by compar- ing it with the distance obtained by the foregoing methods, or any other which will afford the best means of comparison.

No official requirement for qualification or training.

This set of regulations also touches on the idea of combined fire from many guns, and specifically it says:

292. Concentration of fire may be desirable under certain circum- stances ; and arrangements have been sometimes made to secure it by the simultaneous discharge of a number of guns upon some part of an object whose distance is known.
The advantages of these arrangements are not very obvious, excepting in cases where the position of the enemy may be visible from one part of a ship and not from all the guns in the batteries. Even in these cases, however, it requires that all the guns which are to fire in this manner should be regulated by one gun, and all be fired at the same time, which it would be difficult to accomplish ; and, if successful, the simultaneous discharge from many heavy guns may be considered objectionable.
Concentration of fire upon a particular part of an enemy's vessel may be obtained by a general order for the guns to be aimed to strike that part, leaving the Captains of guns to determine the proper time for firing, according to circumstances at the moment. This obviates the objections due to simultaneous firing and would generally be equally effective. In this, as in all other cases at sea, success would depend mainly upon the skill, judgment, and coolness of the Captains of the guns.


In other words, the USN's official opinion on coordinated broadsides under central control was "don't do it".

The 1864 one added that gun captains should be examined by the surgeon with respect to eyesight, but added no qualification requirements.



One of these services is paying greater attention than the other to the cultivation of the skills required for accurate long range fire.
 
I'm guessing the only practical Confederate countermeasure was mines. They had too few of these to do much good.

Sir, the Confederates had a few other tricks up their sleeves when it came to river defense...

Please see...


Cheers,
USS ALASKA
 
I'd like to toss in that mines were hardly "rare."
Electrically triggered torpedoes were rare for the reasons stated earlier in this thread, but contact torpedoes were all over the place.
The Union had a large number of vessels damaged or even destroyed by torpedoes. Take a look at the attrition on Union ships in the naval side of capturing Mobile - frontline vessels were popping left and right, including several monitors.

Infernal Machines the Story of Confederate the Story of the Confederate Submarine and Mine Warfare by Milton F. Perry

The Impact Of Mine Warfare Upon US Naval Operations During The Civil War by LCDR Edwin D. Lindgren USN

Confederate Torpedoes: Two Illustrated 19th Century Works with New Appendices and Photographs by Gabriel J. Rains and Peter S. Michie

Civil War Heavy Explosive Ordnance: A Guide to Large Artillery Projectiles, Torpedoes, and Mines by Jack Bell

"**** the Torpedoes": A Short History of U.S. Naval Mine Countermeasures, 1777-1991 by Tamara Moser Melia


MINE WARFARE HISTORY AND TECHNOLOGY By Gregory K. Hartmann

'America's Use of Sea Mines' by Robert C Duncan

I can also recommend 'Weapons That Wait: Mine Warfare in the U.S. Navy' by Gregory Kemenyi Hartmann

Historians say that mines, or torpedoes, claimed thirty-five Union ships and one Confederate vessel during the Civil War. Gabriel Rains claimed fifty-eight in his postwar memoir, although he does not make clear whether he counted vessels of any size sunk by water-borne mines. Nor does he offer any estimates of how many sailors were killed or wounded by mines.


Mines are a lot like snipers - just the threat of them near your location changes your operations.

Cheers,
USS ALASKA
 
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Sirs, some sources that might be of interest...

Clad in Iron: The American Civil War and the Challenge of British Naval Power by Howard J. Fuller

Civil War Ironclads: The U.S. Navy and Industrial Mobilization by William H. Roberts

The Old Steam Navy: The Ironclads, 1842-1885 by Donald L. Canney

Cheers,
USS ALASKA
 
Sir, the Confederates had a few other tricks up their sleeves when it came to river defense...

Please see...


Cheers,
USS ALASKA
Very interesting! Were they effective?
 
Had the Kyrellian Armada observing from the Rings of Saturn intervened they would've smoked the Monitors.
Nah, in the 1860s they were mostly hanging out in Jupiter's rings.

Which are much better, if you're anywhere Jupiter can hear you.



In all seriousness, the Monitors had some serious flaws but it's hard to see how the Union could have got ships that were all that much better given their industrial constraints. If you can't produce thick hammered or rolled wrought iron in bulk then you need to minimize the amount you armour, because the thickness you need for protection is massive... but at the same time, you'd think a dozen inches of timber backing instead of a layer or two of boilerplate wouldn't have gone amiss!
And a roller path would have been rather less prone to being disabled by a single hit.
 
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