Talos

That unidentified 20 ship plan has the look of a reduced Essex, me-thinks, especially about the bow, and the body plan, so I wondered if she might not be the USS Merrimack, 1798, who, I believe, was also built by William Hackett of Salem. Totally subjective observation, of course ...

I’ve been fascinated with those two particular plans for a while. I included them in one of my profile comparisons, alongside the privateer Rattlesnake and the (incorrect!) Cyane.
 
The 18-gun one is just so weird, compared to the warships I’m used to seeing. More merchant-like for sure, but still too sharp to be a civilian one, too big for an illegal trader. Chapelle argues that she must be a naval or merchant-cruiser. He also suggests that it was a design by Fox because of the nature of her stem.
 
As far as the 20, it’s got the appearance of the typical American frigates of the era. Looking at the plans of John Adams and this ship, they’re virtually identical above the waterline except for size. Chapelle suggests that it was a design for an improved version of Maryland and Patapsco, nearly identical dimensions but with fewer guns and higher gunports to correct the guns on the earlier ships being very low. He also compares the ship to the Brazen-class Cyane post ship, which had more guns on the main deck, but 6pdrs instead of 9pdrs, and was the better sailor because it wasn't as overloaded until the War of 1812 when it carried 32 guns instead. I’ve pointed it out before, but I will again, but Chapelle got the wrong Cyane plans when he sent for them. The ones in the book are the older 18-gun Bittern-class sloop Cyane, not the 26-gun Brazen-class Cyane the Americans captured. Thinking it was the War of 1812 ship, he refitted the drawing with solid bulwarks like most ships of the era received. That’s the plan I have in the comparison I’m linking.
 
As far as the other ships go, Chapelle points out that everything in this era down to sloops tended to be shrunken versions of the 44s, at least above-water style-wise. You can see that comparing John Adams and the 20-gun ship. As long as you get the proportions and dimensions right, you can probably do a fair amount basing off of the 20-gun, Constitution/Constellation/Chesapeake, and the Philly, New York, Boston, and Essex.

Well, Chapelle was guessing that the 20-gun ship is an improved version of Maryland and Patapsco, soooo..... Merrimack should be pretty easy to do a generic Federal frigate of the era on her dimensions. I'm not sure on the other ships since I have to do some research on them first.
 
And yeah, I do the diagrams because it adds a lot to me too. Really puts things in perspective and makes it easy to compare. If there's any particular ships through Chapelle's books that you want to see lined up, let me know, I have many of them scanned already.

Well, Chapelle was guessing that the 20-gun ship is an improved version of Maryland and Patapsco, soooo..... Merrimack should be pretty easy to do a generic Federal frigate of the era on her dimensions. I'm not sure on the other ships since I have to do some research on them first.
 
And yeah, I do the diagrams because it adds a lot to me too. Really puts things in perspective and makes it easy to compare. If there's any particular ships through Chapelle's books that you want to see lined up, let me know, I have many of them scanned already.

I’ve been fascinated with those two particular plans for a while. I included them in one of my profile comparisons, alongside the privateer Rattlesnake and the (incorrect!) Cyane.
 
The 18-gun one is just so weird, compared to the warships I’m used to seeing. More merchant-like for sure, but still too sharp to be a civilian one, too big for an illegal trader. Chapelle argues that she must be a naval or merchant-cruiser. He also suggests that it was a design by Fox because of the nature of her stem.
 
As far as the 20, it’s got the appearance of the typical American frigates of the era. Looking at the plans of John Adams and this ship, they’re virtually identical above the waterline except for size. Chapelle suggests that it was a design for an improved version of Maryland and Patapsco, nearly identical dimensions but with fewer guns and higher gunports to correct the guns on the earlier ships being very low. He also compares the ship to the Brazen-class Cyane post ship, which had more guns on the main deck, but 6pdrs instead of 9pdrs, and was the better sailor because it wasn't as overloaded until the War of 1812 when it carried 32 guns instead. I’ve pointed it out before, but I will again, but Chapelle got the wrong Cyane plans when he sent for them. The ones in the book are the older 18-gun Bittern-class sloop Cyane, not the 26-gun Brazen-class Cyane the Americans captured. Thinking it was the War of 1812 ship, he refitted the drawing with solid bulwarks like most ships of the era received. That’s the plan I have in the comparison I’m linking.
 
As far as the other ships go, Chapelle points out that everything in this era down to sloops tended to be shrunken versions of the 44s, at least above-water style-wise. You can see that comparing John Adams and the 20-gun ship. As long as you get the proportions and dimensions right, you can probably do a fair amount basing off of the 20-gun, Constitution/Constellation/Chesapeake, and the Philly, New York, Boston, and Essex.

I’ve been fascinated with those two particular plans for a while. I included them in one of my profile comparisons, alongside the privateer Rattlesnake and the (incorrect!) Cyane.
 
The 18-gun one is just so weird, compared to the warships I’m used to seeing. More merchant-like for sure, but still too sharp to be a civilian one, too big for an illegal trader. Chapelle argues that she must be a naval or merchant-cruiser. He also suggests that it was a design by Fox because of the nature of her stem.
 
As far as the 20, it’s got the appearance of the typical American frigates of the era. Looking at the plans of John Adams and this ship, they’re virtually identical above the waterline except for size. Chapelle suggests that it was a design for an improved version of Maryland and Patapsco, nearly identical dimensions but with fewer guns and higher gunports to correct the guns on the earlier ships being very low. He also compares the ship to the Brazen-class Cyane post ship, which had more guns on the main deck, but 6pdrs instead of 9pdrs, and was the better sailor because it wasn't as overloaded until the War of 1812 when it carried 32 guns instead. I’ve pointed it out before, but I will again, but Chapelle got the wrong Cyane plans when he sent for them. The ones in the book are the older 18-gun Bittern-class sloop Cyane, not the 26-gun Brazen-class Cyane the Americans captured. Thinking it was the War of 1812 ship, he refitted the drawing with solid bulwarks like most ships of the era received. That’s the plan I have in the comparison I’m linking.
 
As far as the other ships go, Chapelle points out that everything in this era down to sloops tended to be shrunken versions of the 44s, at least above-water style-wise. You can see that comparing John Adams and the 20-gun ship. As long as you get the proportions and dimensions right, you can probably do a fair amount basing off of the 20-gun, Constitution/Constellation/Chesapeake, and the Philly, New York, Boston, and Essex.

Really interesting stuff. I wonder, looking at the table, if some of the difference might be in the construction of the hulls, since the other three examples are all ships of the line. Is there a 32 or 36-gun frigate from the 19th century you might be able to compare it to? That'd be pretty close in class to the 30-gun of 1764.

Whilst working my way through various contemporary treatises, some more legible than others, it occurred to me that for the application of the Archimedes Principle to be effective, it was necessary to be able to estimate the actual weight of the vessel before it was constructed.  I took a detour, as it were, to search out some examples where estimates of a ships weight were given.  The four provided below are just representative cases – there are others.  It is interesting to see how the relative proportion of each part of the ship has, surprisingly, remained rather consistent across classes and decades.  For example, in 1754 the hull was 44,6% of the total weight for a 30 gun frigate, and in 1847 (with much more accurate methods used) it was 54.3% of the total weight for a proposed 80 ship.
 

 
Sources:
Murray, Mungo. 1754. A Treatise on Ship-Building and Navigation. In Three Parts, Wherein the Theory, Practice, and Application of All the Necessary Instruments Are Perspicuously Handled. With the Construction and Use of a New Invented Shipwright’s Sector ... Also Tables of the Sun’s Declination, of Meridional Parts ... To Which Is Added by Way of Appendix, an English Abridgment of Another Treatise on Naval Architecture, Lately Published at Paris by M. Duhamel. London, Printed for D. Henry and R. Cave, for the author. https://archive.org/details/treatiseonshipbu00murr.
 
Rees, Abraham. 1819. Article on Shipbuilding in The Cyclopædia; Or, Universal Dictionary of Arts, Sciences, and Literature. Vol. 32. London : Longman, Hurst, Rees, Orme & Brown [etc.]. http://archive.org/details/cyclopaediaoruni32rees.
 
Edye, John. 1832. Calculations Relating to the Equipment, Displacement, Etc. of Ships and Vessels of War. Hodgson.
 
Read, Samuel, Henry Chatfield, and Augustin Francis Bullock Creuze. 1847. Reports on Naval Construction, 1842-44. W. Clowes.
 
 

Crosspost from the American Sailing Warships thread and not big history or anything, but the receiving ship Independence, a razee'd 74, in drydock in Mare Island, San Francisco 130 years ago today.
 

A hundred and thirty years ago today, USS Independence was in dry dock at Mare Island. She had been floated in on October 30th.
 

 
Nearly thirty years later, in 1915, she was burned and scrapped.
 

 
This is an interesting interior view of her during her time as a receiving ship in Mare Island. Note the truss of the large roof built over her, as well as the hammocks stored in the hammock rails and the three light guns in the gun ports. I believe they are Hotchkiss Revolving Cannons, probably in 37mm.
 

 
A nice color shot of her after they painted her light grey. She wasn’t the only receiving ship to be painted this way, USS Dale was as well.
 

 
A nice shot of her stern to round things out. This gives a good look at the molding on her stern and quarter galleries as well as the laurel wreath badges. It also illustrates an interesting quirk in the design. The quarter galleries aren’t level with the upper deck. Rather, they’re placed half a deck lower, which you can see compared to the eight (8!) stern chase ports. As I haven’t seen this on any of the other liners, and the sail plan of Independence shows them lined up with the decks, I believe it’s a result of the razee-ing process. They probably looked awkward so high up, especially compared to normal US frigates which carried them below the level of the spar deck.
 

 

A hundred and thirty years ago today, USS Independence was in dry dock at Mare Island. She had been floated in on October 30th.
 

 
Nearly thirty years later, in 1915, she was burned and scrapped.
 

 
This is an interesting interior view of her during her time as a receiving ship in Mare Island. Note the truss of the large roof built over her, as well as the hammocks stored in the hammock rails and the three light guns in the gun ports. I believe they are Hotchkiss Revolving Cannons, probably in 37mm.
 

 
A nice color shot of her after they painted her light grey. She wasn’t the only receiving ship to be painted this way, USS Dale was as well.
 

 
A nice shot of her stern to round things out. This gives a good look at the molding on her stern and quarter galleries as well as the laurel wreath badges. It also illustrates an interesting quirk in the design. The quarter galleries aren’t level with the upper deck. Rather, they’re placed half a deck lower, which you can see compared to the eight (8!) stern chase ports. As I haven’t seen this on any of the other liners, and the sail plan of Independence shows them lined up with the decks, I believe it’s a result of the razee-ing process. They probably looked awkward so high up, especially compared to normal US frigates which carried them below the level of the spar deck.
 

 

Crosspost from the American Sailing Warships thread and not big history or anything, but the receiving ship Independence, a razee'd 74, in drydock in Mare Island, San Francisco 130 years ago today.
 

A hundred and thirty years ago today, USS Independence was in dry dock at Mare Island. She had been floated in on October 30th.
 

 
Nearly thirty years later, in 1915, she was burned and scrapped.
 

 
This is an interesting interior view of her during her time as a receiving ship in Mare Island. Note the truss of the large roof built over her, as well as the hammocks stored in the hammock rails and the three light guns in the gun ports. I believe they are Hotchkiss Revolving Cannons, probably in 37mm.
 

 
A nice color shot of her after they painted her light grey. She wasn’t the only receiving ship to be painted this way, USS Dale was as well.
 

 
A nice shot of her stern to round things out. This gives a good look at the molding on her stern and quarter galleries as well as the laurel wreath badges. It also illustrates an interesting quirk in the design. The quarter galleries aren’t level with the upper deck. Rather, they’re placed half a deck lower, which you can see compared to the eight (8!) stern chase ports. As I haven’t seen this on any of the other liners, and the sail plan of Independence shows them lined up with the decks, I believe it’s a result of the razee-ing process. They probably looked awkward so high up, especially compared to normal US frigates which carried them below the level of the spar deck.
 

 

Crosspost from the American Sailing Warships thread and not big history or anything, but the receiving ship Independence, a razee'd 74, in drydock in Mare Island, San Francisco 130 years ago today.
 

Crosspost from the American Sailing Warships thread and not big history or anything, but the receiving ship Independence, a razee'd 74, in drydock in Mare Island, San Francisco 130 years ago today.
 

A hundred and thirty years ago today, USS Independence was in dry dock at Mare Island. She had been floated in on October 30th.
 

 
Nearly thirty years later, in 1915, she was burned and scrapped.
 

 
This is an interesting interior view of her during her time as a receiving ship in Mare Island. Note the truss of the large roof built over her, as well as the hammocks stored in the hammock rails and the three light guns in the gun ports. I believe they are Hotchkiss Revolving Cannons, probably in 37mm.
 

 
A nice color shot of her after they painted her light grey. She wasn’t the only receiving ship to be painted this way, USS Dale was as well.
 

 
A nice shot of her stern to round things out. This gives a good look at the molding on her stern and quarter galleries as well as the laurel wreath badges. It also illustrates an interesting quirk in the design. The quarter galleries aren’t level with the upper deck. Rather, they’re placed half a deck lower, which you can see compared to the eight (8!) stern chase ports. As I haven’t seen this on any of the other liners, and the sail plan of Independence shows them lined up with the decks, I believe it’s a result of the razee-ing process. They probably looked awkward so high up, especially compared to normal US frigates which carried them below the level of the spar deck.
 

 

Crosspost from the American Sailing Warships thread and not big history or anything, but the receiving ship Independence, a razee'd 74, in drydock in Mare Island, San Francisco 130 years ago today.
 

A hundred and thirty years ago today, USS Independence was in dry dock at Mare Island. She had been floated in on October 30th.
 

 
Nearly thirty years later, in 1915, she was burned and scrapped.
 

 
This is an interesting interior view of her during her time as a receiving ship in Mare Island. Note the truss of the large roof built over her, as well as the hammocks stored in the hammock rails and the three light guns in the gun ports. I believe they are Hotchkiss Revolving Cannons, probably in 37mm.
 

 
A nice color shot of her after they painted her light grey. She wasn’t the only receiving ship to be painted this way, USS Dale was as well.
 

 
A nice shot of her stern to round things out. This gives a good look at the molding on her stern and quarter galleries as well as the laurel wreath badges. It also illustrates an interesting quirk in the design. The quarter galleries aren’t level with the upper deck. Rather, they’re placed half a deck lower, which you can see compared to the eight (8!) stern chase ports. As I haven’t seen this on any of the other liners, and the sail plan of Independence shows them lined up with the decks, I believe it’s a result of the razee-ing process. They probably looked awkward so high up, especially compared to normal US frigates which carried them below the level of the spar deck.
 

 

A hundred and thirty years ago today, USS Independence was in dry dock at Mare Island. She had been floated in on October 30th.
 

 
Nearly thirty years later, in 1915, she was burned and scrapped.
 

 
This is an interesting interior view of her during her time as a receiving ship in Mare Island. Note the truss of the large roof built over her, as well as the hammocks stored in the hammock rails and the three light guns in the gun ports. I believe they are Hotchkiss Revolving Cannons, probably in 37mm.
 

 
A nice color shot of her after they painted her light grey. She wasn’t the only receiving ship to be painted this way, USS Dale was as well.
 

 
A nice shot of her stern to round things out. This gives a good look at the molding on her stern and quarter galleries as well as the laurel wreath badges. It also illustrates an interesting quirk in the design. The quarter galleries aren’t level with the upper deck. Rather, they’re placed half a deck lower, which you can see compared to the eight (8!) stern chase ports. As I haven’t seen this on any of the other liners, and the sail plan of Independence shows them lined up with the decks, I believe it’s a result of the razee-ing process. They probably looked awkward so high up, especially compared to normal US frigates which carried them below the level of the spar deck.
 

 

Actually, Santee was built with the pivots too. You can see her aft and forward pivot ports in various pictures. Silverstone lists her as being armed from the start with 64-pounder shot and shell guns fore and aft. These were the biggest guns in the inventory by weight at the time, weight 20 cwt more than the early, weak 10” (not the Dahlgren, the Paixhan’s -style gun), 106 cwt total. The X-inch Dahlgren, at least the original model of it, weighs just slightly more at 107 cwt. I did a drawing of it which you can see on the previous page of this thread. It was that big to enable it to fire solid shot, double-shot the gun, etc. The lighter shell guns of the same caliber (8”) were intended to  mostly fire the lighter shells, though they could fire solid shot in a pinch if they had to. The 64-pdrs were limited to only a few ships, mostly these and the paddle-wheel steamers where they needed the extra punch to make up for the lack of guns due to the paddle boxes.
 
Speaking of paddle-wheelers, the bridge on Sabine in those pictures is called a flying bridge. They were an evolution of a bridge structure placed between the wheels of a side-wheeler where a Captain could have a good view. Previously Captains had their spot at the quarterdeck so they could see all of their rigging and sails clearly, but this was becoming less important with steamers. Flying bridges were getting popular in the Civil War era, you can see them on a variety of vessels, including steam sloops and gunboats.
 
With regards to the poop deck and aft pivot gun, that decking is not robust enough to take a X-inch Dahlgren’s weight and recoil. You’ll also notice the dark band on the mast right about level with the railing. That’s where the spanker boom attaches to the mast, there’s zero room for a cannon under it, it’s waist high. The last shot you have is indeed one of Santee when she’s a training ship armed with X-inch Dahlgrens fore and aft and a set of VIII-inch Dahlgrens on her upper deck (plus it looks like a Parrott up front). In this uncropped version of the picture, you can see the pivot wheels for the aft pivot resting on the deck. Also look all the way in front behind the Parrot and you can see the interior of Santee’s forward pivot port.

 
Interestingly, this shot of Santee roofed over only shows the rear pivot port (the double-wide window aft) and blank planking up front. I imagine they replanked that area because the forward pivot port would be a long, structurally weak part to mount the roof on.

 
Here’s a shot of Santee (left) and Constitution during the War. Santee’s forward pivot port is open.
https://www.loc.gov/resource/ppmsca.33945/
 
Found this while I was looking up information today. Apparently one of Sabine’s 6.4” (100-pounder) Parrott Rifles survives in Michigan as a monument. http://www.hmdb.org/marker.asp?marker=98250 She might even be the large Parrott rifle we see sticking out of Sabine’s aft pivot port in this picture.
 
http://www.loc.gov/pictures/resource/cwpb.03821/ (be sure to download the full-size picture to zoom in. Also note the Royal Navy paddle-wheeled warship back there with the boats on top of the boxes and that very distinctive mid-century Royal Navy quarter gallery and stern design. You can also see guys standing on Sabine’s flying bridge in that picture, helping you to place it exactly)
 
Random unrelated picture of Saratoga I came across today too.

Glad I could help. If you have more questions, please do ask. I enjoy the discussion and the research, it's a lot of fun. Also very glad to see the billethead survived, especially after finding that picture of it mounted on a building at the shipyard. Is it in an indoor or outdoor display?

Actually, Santee was built with the pivots too. You can see her aft and forward pivot ports in various pictures. Silverstone lists her as being armed from the start with 64-pounder shot and shell guns fore and aft. These were the biggest guns in the inventory by weight at the time, weight 20 cwt more than the early, weak 10” (not the Dahlgren, the Paixhan’s -style gun), 106 cwt total. The X-inch Dahlgren, at least the original model of it, weighs just slightly more at 107 cwt. I did a drawing of it which you can see on the previous page of this thread. It was that big to enable it to fire solid shot, double-shot the gun, etc. The lighter shell guns of the same caliber (8”) were intended to  mostly fire the lighter shells, though they could fire solid shot in a pinch if they had to. The 64-pdrs were limited to only a few ships, mostly these and the paddle-wheel steamers where they needed the extra punch to make up for the lack of guns due to the paddle boxes.
 
Speaking of paddle-wheelers, the bridge on Sabine in those pictures is called a flying bridge. They were an evolution of a bridge structure placed between the wheels of a side-wheeler where a Captain could have a good view. Previously Captains had their spot at the quarterdeck so they could see all of their rigging and sails clearly, but this was becoming less important with steamers. Flying bridges were getting popular in the Civil War era, you can see them on a variety of vessels, including steam sloops and gunboats.
 
With regards to the poop deck and aft pivot gun, that decking is not robust enough to take a X-inch Dahlgren’s weight and recoil. You’ll also notice the dark band on the mast right about level with the railing. That’s where the spanker boom attaches to the mast, there’s zero room for a cannon under it, it’s waist high. The last shot you have is indeed one of Santee when she’s a training ship armed with X-inch Dahlgrens fore and aft and a set of VIII-inch Dahlgrens on her upper deck (plus it looks like a Parrott up front). In this uncropped version of the picture, you can see the pivot wheels for the aft pivot resting on the deck. Also look all the way in front behind the Parrot and you can see the interior of Santee’s forward pivot port.

 
Interestingly, this shot of Santee roofed over only shows the rear pivot port (the double-wide window aft) and blank planking up front. I imagine they replanked that area because the forward pivot port would be a long, structurally weak part to mount the roof on.

 
Here’s a shot of Santee (left) and Constitution during the War. Santee’s forward pivot port is open.
https://www.loc.gov/resource/ppmsca.33945/
 
Found this while I was looking up information today. Apparently one of Sabine’s 6.4” (100-pounder) Parrott Rifles survives in Michigan as a monument. http://www.hmdb.org/marker.asp?marker=98250 She might even be the large Parrott rifle we see sticking out of Sabine’s aft pivot port in this picture.
 
http://www.loc.gov/pictures/resource/cwpb.03821/ (be sure to download the full-size picture to zoom in. Also note the Royal Navy paddle-wheeled warship back there with the boats on top of the boxes and that very distinctive mid-century Royal Navy quarter gallery and stern design. You can also see guys standing on Sabine’s flying bridge in that picture, helping you to place it exactly)
 
Random unrelated picture of Saratoga I came across today too.

Actually, Santee was built with the pivots too. You can see her aft and forward pivot ports in various pictures. Silverstone lists her as being armed from the start with 64-pounder shot and shell guns fore and aft. These were the biggest guns in the inventory by weight at the time, weight 20 cwt more than the early, weak 10” (not the Dahlgren, the Paixhan’s -style gun), 106 cwt total. The X-inch Dahlgren, at least the original model of it, weighs just slightly more at 107 cwt. I did a drawing of it which you can see on the previous page of this thread. It was that big to enable it to fire solid shot, double-shot the gun, etc. The lighter shell guns of the same caliber (8”) were intended to  mostly fire the lighter shells, though they could fire solid shot in a pinch if they had to. The 64-pdrs were limited to only a few ships, mostly these and the paddle-wheel steamers where they needed the extra punch to make up for the lack of guns due to the paddle boxes.
 
Speaking of paddle-wheelers, the bridge on Sabine in those pictures is called a flying bridge. They were an evolution of a bridge structure placed between the wheels of a side-wheeler where a Captain could have a good view. Previously Captains had their spot at the quarterdeck so they could see all of their rigging and sails clearly, but this was becoming less important with steamers. Flying bridges were getting popular in the Civil War era, you can see them on a variety of vessels, including steam sloops and gunboats.
 
With regards to the poop deck and aft pivot gun, that decking is not robust enough to take a X-inch Dahlgren’s weight and recoil. You’ll also notice the dark band on the mast right about level with the railing. That’s where the spanker boom attaches to the mast, there’s zero room for a cannon under it, it’s waist high. The last shot you have is indeed one of Santee when she’s a training ship armed with X-inch Dahlgrens fore and aft and a set of VIII-inch Dahlgrens on her upper deck (plus it looks like a Parrott up front). In this uncropped version of the picture, you can see the pivot wheels for the aft pivot resting on the deck. Also look all the way in front behind the Parrot and you can see the interior of Santee’s forward pivot port.

 
Interestingly, this shot of Santee roofed over only shows the rear pivot port (the double-wide window aft) and blank planking up front. I imagine they replanked that area because the forward pivot port would be a long, structurally weak part to mount the roof on.

 
Here’s a shot of Santee (left) and Constitution during the War. Santee’s forward pivot port is open.
https://www.loc.gov/resource/ppmsca.33945/
 
Found this while I was looking up information today. Apparently one of Sabine’s 6.4” (100-pounder) Parrott Rifles survives in Michigan as a monument. http://www.hmdb.org/marker.asp?marker=98250 She might even be the large Parrott rifle we see sticking out of Sabine’s aft pivot port in this picture.
 
http://www.loc.gov/pictures/resource/cwpb.03821/ (be sure to download the full-size picture to zoom in. Also note the Royal Navy paddle-wheeled warship back there with the boats on top of the boxes and that very distinctive mid-century Royal Navy quarter gallery and stern design. You can also see guys standing on Sabine’s flying bridge in that picture, helping you to place it exactly)
 
Random unrelated picture of Saratoga I came across today too.

Actually, Santee was built with the pivots too. You can see her aft and forward pivot ports in various pictures. Silverstone lists her as being armed from the start with 64-pounder shot and shell guns fore and aft. These were the biggest guns in the inventory by weight at the time, weight 20 cwt more than the early, weak 10” (not the Dahlgren, the Paixhan’s -style gun), 106 cwt total. The X-inch Dahlgren, at least the original model of it, weighs just slightly more at 107 cwt. I did a drawing of it which you can see on the previous page of this thread. It was that big to enable it to fire solid shot, double-shot the gun, etc. The lighter shell guns of the same caliber (8”) were intended to  mostly fire the lighter shells, though they could fire solid shot in a pinch if they had to. The 64-pdrs were limited to only a few ships, mostly these and the paddle-wheel steamers where they needed the extra punch to make up for the lack of guns due to the paddle boxes.
 
Speaking of paddle-wheelers, the bridge on Sabine in those pictures is called a flying bridge. They were an evolution of a bridge structure placed between the wheels of a side-wheeler where a Captain could have a good view. Previously Captains had their spot at the quarterdeck so they could see all of their rigging and sails clearly, but this was becoming less important with steamers. Flying bridges were getting popular in the Civil War era, you can see them on a variety of vessels, including steam sloops and gunboats.
 
With regards to the poop deck and aft pivot gun, that decking is not robust enough to take a X-inch Dahlgren’s weight and recoil. You’ll also notice the dark band on the mast right about level with the railing. That’s where the spanker boom attaches to the mast, there’s zero room for a cannon under it, it’s waist high. The last shot you have is indeed one of Santee when she’s a training ship armed with X-inch Dahlgrens fore and aft and a set of VIII-inch Dahlgrens on her upper deck (plus it looks like a Parrott up front). In this uncropped version of the picture, you can see the pivot wheels for the aft pivot resting on the deck. Also look all the way in front behind the Parrot and you can see the interior of Santee’s forward pivot port.

 
Interestingly, this shot of Santee roofed over only shows the rear pivot port (the double-wide window aft) and blank planking up front. I imagine they replanked that area because the forward pivot port would be a long, structurally weak part to mount the roof on.

 
Here’s a shot of Santee (left) and Constitution during the War. Santee’s forward pivot port is open.
https://www.loc.gov/resource/ppmsca.33945/
 
Found this while I was looking up information today. Apparently one of Sabine’s 6.4” (100-pounder) Parrott Rifles survives in Michigan as a monument. http://www.hmdb.org/marker.asp?marker=98250 She might even be the large Parrott rifle we see sticking out of Sabine’s aft pivot port in this picture.
 
http://www.loc.gov/pictures/resource/cwpb.03821/ (be sure to download the full-size picture to zoom in. Also note the Royal Navy paddle-wheeled warship back there with the boats on top of the boxes and that very distinctive mid-century Royal Navy quarter gallery and stern design. You can also see guys standing on Sabine’s flying bridge in that picture, helping you to place it exactly)
 
Random unrelated picture of Saratoga I came across today too.

i'm building the Sabine to represent the ship that ended up getting scrapped here in Rockland in 1880 because parts of the ship are all over town. The billethead is indoors at the art museum. Some of the hull timbers are in the old marine rail at the snow yard, the gavels at our courthouse are made from Sabine wood, and two of the deckhouses survive. The midship galleyhouse and a queer little wheelhouse looking thing. It seems for the duration of the war the Sabine was flushdeck with house midships and forward. While her sister Santee was armed with two decks full of broadside guns, the Sabine sported for and aft pivots. The Sabine had an interesting "bridge" over the wheel I would assume for officers: 
    After the war she got a poopdeck. I think the funny little wheelhouse in town is one of the pieces from under the poop. I'm still wondering about the stern pivot on the poop roof. in this shot of the Santee (?) look at the pivot in the forground: is that thing sitting on a roof?