A beautiful thing to behold! I especially admire that final rendering.
Thank you for the clearly described method as well. I can replicate this particular technique in Rhino3D. It reminds me a bit of a method for setting up small boat hulls for lap strake planking.
I hope there exist detailed drawings and ideally a plating map for the USS Onondaga.
My guess would be that Onondaga was designed by the Navy, by Isherwood and Lenthall, and modified on the ways to use Ericsson turrets and turret machinery. It is not clear to me the source of the engine design.
Before Hampton Roads, Isherwood and Lenthall were ready with a twin turret Monitor-esque design and had even obtained congressional approval to fund its construction in quantity. Their concept is cited in the histories as "The Bureau Design." and featured twin Cole turrets, all iron construction, and twin screws.
A derivative of the "Bureau Design" was ultimately constructed as a series of four twin turret monitors, including USS Monadnock.
It would be my guess, at this point, that the USS Onondaga was a Navy-designed precursor of these four monitors. Nominally the designer was the contractor, George Quintard, but I am wondering now if the ship's real designers were not Isherwood and Lenthall.
This engineering history was no doubt obscured by the ferocious political infighting between Ericsson and his partners and Isherwood/Lenthall. But some drawings exist in the national archives and some may also exist in the archives of the French navy. Maryland Silver has a few Onondaga drawings available, listed on the catalog page here:
http://www.marylandsilver.com/Ship.htmIf, as I am beginning to suspect, John Ericsson did not get involved much in the design of the USS Onondaga, then from our point of view that's good, since so many of Ericsson's drawings were destroyed by his executor.
Anyway Dean, aesthetically, I hope those beautiful bands depicted in your rendering turn out to have actually existed -- they are really striking! Thank you for showing how to achieve these!
Michael