Freeboard of CSS Virginia

To be fair to him , a lot of plans credited to him were actually by his draughtsman, and some didn't get to him ,although he was supposed to see every plan authorised. He was here, there and everywhere, and maybe he signed some plans that weren't right in the process.
 
Just for fun, from the 1991 Turner TV movie, "Ironclads":
Picture 10.png
 
Notice how the water bulges up over the submerged bow, and then there's a bit of a hollow alongside the hull? Similar to what we see with a modern submarine on the surface.

Having the fore and aft hull submerged is further reason why Virginia would not have been fit for the open ocean. If she were pitching, each end in turn would go under water and then try to rise against the weight of the water, imposing considerable strain on the hull and likely leading to hogging or leakage. The flat surface is the worst for draining water off. The bow bulwark might make things worse in this situation by making it harder for water to drain off the deck.
 
Having the fore and aft hull submerged is further reason why Virginia would not have been fit for the open ocean. If she were pitching, each end in turn would go under water and then try to rise against the weight of the water, imposing considerable strain on the hull and likely leading to hogging or leakage. The flat surface is the worst for draining water off. The bow bulwark might make things worse in this situation by making it harder for water to drain off the deck.

This is why I believe, in the absence of a firm answer either way, that the built-up cutwater on the bow would have been decked over. It would add little additional weight, unlike keeping it open where it would fill with water that could not be drained quickly enough. Like driving around with a full hot tub strapped to the hood of your car.
 
Virginia went into action without the gunport covers " as they were useless" (George T Sinclair). The solid rolled iron ones fitted afterward were pivoted in the top right hand corner and swung upwards.
I think Andy is right about the forward breakwater, but the aft extention over the screw and rudder was certainly below or just at the surface, Remember that the ship only just got down to her marks.
 
Yes, well, however it worked, thanks for the imagery- it's REALLY difficult for a non-engineer to figure out how these things maneuvered, much less floated. I'm ' ok ' with boats in general, you can wrap your head around things like buoyancy, etc. These ironclads, always look to be on the edge of sinking regardless, just by looking at them plus thinking about the weight they carted around.

Scuse the nosiness, was this another Civil War movie where James N. crafted the realisms ( for want of a better word ) ? In another thread, he posted a photo in answer to a question in the air about how on earth those absurdly heavy guns were managed- very cool, a set containing the means by which they would have been set in place. I know this forum has a whole CW section on education- the entire THING is an education, no idea how they figure out what goes there.
 
To be fair to him , a lot of plans credited to him were actually by his draughtsman, and some didn't get to him ,although he was supposed to see every plan authorised. He was here, there and everywhere, and maybe he signed some plans that weren't right in the process.
I should perhaps have added that his major mistake with Virginia as that he forgot to compensate for the weight of sailing rig and stores, that's why she was light, and the reason for the extra ballast. Hindsight says that should have been used for extra protection.
 
This is why I believe, in the absence of a firm answer either way, that the built-up cutwater on the bow would have been decked over. It would add little additional weight, unlike keeping it open where it would fill with water that could not be drained quickly enough. Like driving around with a full hot tub strapped to the hood of your car.
I've been thinking about that as well Andy. I am coming round to agreeing with you, ( about the Virginia that is, my car wouldn't take a hot tub !) and will alter my drawings accordingly..
 
There is an ocean plugin for Blender. That is what I used for my ocean renders of the Tecumseh, Tennessee and Manassas.

I can see if I can get some normal or displacement maps baked out that you can use in your renderer .

EDIT: Here are a few I had in my Tecumseh folder. They aren't baked out of Blender, but they give a good water effect.

https://www.dropbox.com/s/ux6ar29mw3seksc/variouswaterdisp.zip?dl=0

Show us how it turned out!!! :D
 
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I should perhaps have added that his major mistake with Virginia as that he forgot to compensate for the weight of sailing rig and stores, that's why she was light, and the reason for the extra ballast. Hindsight says that should have been used for extra protection.
True, at least some of it could have been used for extra protection as the missing weight (mast and sails) was high up. I don't think a true GZ curve exists, though, since the method was pretty much invented in the mid-1860s in Britain IIRC (with Captain one of the first to be tested).
OTOH it's also mentioned that the ballast was needed for stability.

It looks like post-Hampton she had three hundred tons of ballast in her. A waterline belt below the 'shield' would have been very roughly 650 feet long, and 100 tons of ballasting being changed to a waterline belt would allow for about four inches of armour thickness (four layers of 40lb plate) two feet high.
That combination would have made her both more able to accept different load conditions (thus increasing tactical flexibility) and generally safer in combat. 40lb plate is also comparatively available.

For the rest of the ballasting I'd probably prefer to put extra cannonballs in! That was a big problem at the historical Hampton Roads, she didn't have enough cannonballs for two days of fighting as she expended most of them as e.g. hot-shot on the first day and was reduced to shell.
 
True, at least some of it could have been used for extra protection as the missing weight (mast and sails) was high up. I don't think a true GZ curve exists, though, since the method was pretty much invented in the mid-1860s in Britain IIRC (with Captain one of the first to be tested).
OTOH it's also mentioned that the ballast was needed for stability.

It looks like post-Hampton she had three hundred tons of ballast in her. A waterline belt below the 'shield' would have been very roughly 650 feet long, and 100 tons of ballasting being changed to a waterline belt would allow for about four inches of armour thickness (four layers of 40lb plate) two feet high.
That combination would have made her both more able to accept different load conditions (thus increasing tactical flexibility) and generally safer in combat. 40lb plate is also comparatively available.

For the rest of the ballasting I'd probably prefer to put extra cannonballs in! That was a big problem at the historical Hampton Roads, she didn't have enough cannonballs for two days of fighting as she expended most of them as e.g. hot-shot on the first day and was reduced to shell.

Proposed alterations

George T Sinclair proposed that Virginia’s casemate armour should be increased to 6”, and that level of protection should be extended to 6 feet below the knuckle, and made into a full belt. The weight needed for this increase would be gained by removing the 340 or so tons of extra ballast which had been placed in the ship. The armour should be extended into a ram which should be square in section with sharp edges, which would gouge into an enemy hull in a glancing blow collision. He thought her draught would then be approximately 20ft.
J.L.Porter altered the replacement ram accordingly but protection was not increased.
Sinclair also suggested closing the four bow and stern quarter ports, and opening new ones to enable the 7” guns to fire on the broadside. This would have meant an internal shuffle of fittings as the port side ports would have to be moved to accommodate the new arrangement. As Brooke wanted to substitute rifled guns for the 6 - 9” smoothbores, some rearrangement would have had to be done anyway.

Brooke also wanted two 300pdr guns to be specially made for the Virginia. He had obtained details of the Armstrong 10.5” smoothbore which had been rifled to produce the 300pdr MLR.
It would be interesting to know whether he had the drawings, and if so, if he wanted to produce his own version at Tredegar, or get them from Britain. I tend to think he wanted to produce his own version.
 
Hm, that would be an interesting result. I'd be worried about the stability for moving all the ballast higher into the ship.
The replacement ram would be a good feature for facing monitors - hole them below the waterline and they sink pretty quickly - and hot-shot proved better at dealing with wooden vessels anyway.
20 foot of draft would be interesting, actually - the limiting draft on the Potomac is Mattawoman Muds at 19.5 feet low tide with a 3 foot tidal sweep, so a 20 foot draft Virginia could theoretically come up the Potomac.
Closing the quarter ports... tricky. Virginia had a very slow turn and having all-around fire would be important.
If Brooke could produce a gun as strong as the Armstrong 300pdr, that would be a total game-changer. The Warrior armour resisted at about 61 foot tons per inch of circumference, stronger than any armour in North America at the time, and in testing the 300pdr put shot right through the Warrior target, apparently at 200 yards (though it did break up in the process).

If Brooke's metallurgy was as good as Armstrong's, then that gun could have basically one-shot the Monitor turret (which was weaker than Warrior as a result of the laminate construction, lack of backing, and low quality of the iron used - basically you'd get fragments of the shot and a large quantity of the turret iron being fired at speed into the cramped interior of the turret, ouch!) and could have penetrated both Galena and New Ironsides (neither one being as tough as Warrior either.)
 
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I don't think a true GZ curve exists, though, since the method was pretty much invented in the mid-1860s in Britain IIRC (with Captain one of the first to be tested).
Well, I underestimated naval nerds. Someone did a full analysis of Virginia including several GZ curves:

https://vtechworks.lib.vt.edu/bitstream/handle/10919/74944/Marickovich_NE_T_2017.pdf?sequence=3
(Curves are on numbered page 56 onwards)
What's interesting about the analysis is that it suggests that the centre of gravity position is very important and that the ballasting may indeed have been necessary. On the other hand, Captain's GZ curve has maximum righting lever of 20cm at 15 degrees and Virginia's worst-case is about the same - and Captain was literally blown over by a dynamic sail load, so perhaps Virginia would have been okay in sheltered water and without sails.

One other nifty point raised is that the immersion of the gun ports (if closed) may not have been fatal, but the immersion of the inclined armour deck would have been owing to the armour structure as cross-hatched rail ties instead of single strake.
 
Following up on the Brooke rifle point, a source here:
https://markerhunter.wordpress.com/2013/09/01/7-in-3-band-brooke-rifle/
states that the triple-band 7" Brooke rifle could handle 30 lbs service charge and the double-band could manage 20 lbs. This is very good indeed - it's better than Dahlgren's guns of the same size and indeed somewhat better than the 68 pounder line of British 8" smoothbores - though the process to avoid bursting was rather inefficient (the triple-banded 7" rifle weighing double what a British 8" smoothbore did) and it seems like there was friction in the barrel. Nevertheless, this implies that Booke could indeed have produced a piece able to handle powder loads of comparable scale to the 300-lber Armstrong rifle.
 
Well, I underestimated naval nerds. Someone did a full analysis of Virginia including several GZ curves:

https://vtechworks.lib.vt.edu/bitstream/handle/10919/74944/Marickovich_NE_T_2017.pdf?sequence=3
(Curves are on numbered page 56 onwards)
What's interesting about the analysis is that it suggests that the centre of gravity position is very important and that the ballasting may indeed have been necessary. On the other hand, Captain's GZ curve has maximum righting lever of 20cm at 15 degrees and Virginia's worst-case is about the same - and Captain was literally blown over by a dynamic sail load, so perhaps Virginia would have been okay in sheltered water and without sails.

One other nifty point raised is that the immersion of the gun ports (if closed) may not have been fatal, but the immersion of the inclined armour deck would have been owing to the armour structure as cross-hatched rail ties instead of single strake.
Thanks for that, I'd not seen that before. Certainly if her gunport covers had been stoppers that would be true, but I'm not sure they were, in fact I don't think any CSN ironclad had port stoppers, except perhaps Mississippi, and the reference is vague on that. effectively Virginia's hurricane deck was not seatight -or even waterproof !
 
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