Not sure any of this will help...
Plan of turret for Passaic class monitors
View attachment 543172
...from
Monitors of the U.S. Navy, 1861-1937, Volume 2 by Richard H. Webber
Difference between Coles and Ericsson turrets
thefourthmaninaboat
Sep 3, 2014
Both turrets seem fairly similar in outwards appearance; both are cylindrical iron constructions, containing one or two guns. The difference between the two systems came in how they were supported and rotated. The Ericsson turret sat on the upper deck, standing eight-nine feet clear of the deck. It rotated around a central spindle which pivoted in the hold; this supported the weight of the turret in action. The Coles turret pierced through the upper deck, resting instead on the lower deck. It therefore had a lower profile, standing only four feet clear of the deck. The edges of the turret sat on a roller path on the lower deck, letting the turret as a whole rotate.
These two systems had different advantages and disadvantages. For the Ericsson system, the spindle imposed two main constraints on the turret. Firstly, the spindle was in the centre of the turret. This meant that any penetration through to the lower decks had to be off centre, and therefore could not be accessed throughout the full range of the turret's rotation. This limited the crew's ability to access the turret, and to pass ammunition - typically, the crew of an Ericsson turret had to rotate it to the centreline to pass new ammunition into the turret, slowing the already glacial pace of reloading for muzzle-loading guns. This was not a problem for the Coles turret. As this was supported at the edges, the turret centre was always available for shells to be passed through. The spindle was also not in constant operation. When the ship was not in action, the turret stayed in contact with the deck. Prior to going into action, the spindle and turret had to be jacked up by about an inch to allow the turret to rotate. This imposed a delay, which could by a problem if a ship was surprised. The gap created by the raising of the turret also meant that enemy shells could jam the turret if they impacted its base. The base of the Coles turret was protected, and the turret needed little preparation for action. The Coles turret, meanwhile, required more precise engineering than the Ericsson. As the turret passed through the upper deck, and did not sit on it, it also created paths for water to leak into the ship. These leak paths could be blocked with canvas for long passages, but it still remained a problem in action.
Monitor's turret measured 20 ft (6.1 m) in diameter and 9 ft (2.7 m) high, constructed with 8 inches (20 cm) of armor (11 inches in front at the gun ports) rendering the overall vessel somewhat top heavy. Its rounded shape helped to deflect cannon shot.[33][34] A pair of steam-powered donkey engines rotated the turret through a set of gears; a full rotation was made in 22.5 seconds during testing on 9 February 1862.[35] Fine control of the turret proved to be difficult; as there was no brake the steam engines would have to be placed in reverse if the turret overshot its mark, or another full rotation would have to be made. The only way to see out of the turret was through the gun ports; when the guns were not in use, or withdrawn for reloading during battle, heavy iron port stoppers would swing down into place to close the gunports.[36] Including the guns, the turret weighed approximately 160 long tons (163 t); the entire weight rested on an iron spindle that had to be jacked up using a wedge before the turret could rotate.[37] The spindle was 9 inches (23 cm) in diameter which gave it ten times the strength needed in preventing the turret from sliding sideways.[38] When not in use, the turret rested on a brass ring on the deck that was intended to form a watertight seal. In service, however, this proved to leak heavily, despite caulking by the crew.[37] The gap between the turret and the deck proved to be a problem as debris and shell fragments entered the gap and jammed the turrets of several Passaic-class monitors, which used the same turret design, during the First Battle of Charleston Harbor in April 1863.[39] Direct hits on the turret with heavy shot could bend the spindle, which could also jam the turret.[40] To gain access to the turret from below, or to hoist up powder and shot during battle, the turret had to rotate to face starboard, which would line up the entry hatch in the floor of the turret with an opening in the deck below.[41][42] The roof of the turret was lightly built to facilitate any needed exchange of the ship's guns and to improve ventilation, with only gravity holding the roof plates in place.[43]
...from wiki but sourced from...
Baxter, James Phinney, 3rd (1968) [1933].
The Introduction of the Ironclad Warship. Hamden, Connecticut: Archon Books. OCLC 695838727.
Broadwater, John D. (2012).
USS Monitor: A Historic Ship Completes Its Final Voyage. Texas A&M University Press. ISBN 978-1-60344-473-6.
Canney, Donald L. (1993).
The Old Steam Navy. Vol. 2: The Ironclads, 1842–1885. Annapolis, Maryland: Naval Institute Press. ISBN 978-0-87021-586-5.
Clancy, Paul (2013).
Ironclad; The Epic Battle, Calamitous Loss, and Historic Recovery of the USS Monitor. New York: Koehler Books. ISBN 978-1-938467-11-0.
McCordock, Robert Stanley (1938).
The Yankee Cheese Box. Dorrance.
Mindell, David A. (2000).
War, Technology, and Experience Aboard the USS Monitor. Johns Hopkins University Press. ISBN 978-0-8018-6250-2.
Thompson, Stephen C. (1990).
"The Design and Construction of the USS Monitor". Warship International. XXVII (3). ISSN 0043-0374.
Wilson, H. W. (1896).
Ironclads in Action: A Sketch of Naval Warfare From 1855 to 1895. Vol. 1. Boston: Little, Brown.
HTHs,
USS ALASKA
Bringing the